Patent Publication Number: US-2023161511-A1

Title: Command block management

Description:
CROSS REFERENCE 
     The present application for patent is a continuation of U.S. patent application Ser. No. 16/579,153 by Boehm et al., entitled “COMMAND BLOCK MANAGEMENT,” filed Sep. 23, 2019, which claims priority to U.S. Provisional Patent Application No. 62/746,284 by Boehm et al., entitled “COMMAND BLOCK MANAGEMENT,” filed Oct. 16, 2018, each of which is assigned to the assignee hereof and each of which is expressly incorporated by reference in its entirety herein. 
    
    
     BACKGROUND 
     The following relates generally to a system that includes at least one memory device and more specifically to command block management. 
     Memory devices are widely used to store information in various electronic devices such as computers, wireless communication devices, cameras, digital displays, and the like. Information is stored by programming different states of a memory device. For example, binary devices most often store one of two states, often denoted by a logic 1 or a logic 0. In other devices, more than two states may be stored. To access the stored information, a component of the device may read, or sense, at least one stored state in the memory device. To store information, a component of the device may write, or program, the state in the memory device. 
     Types of memory devices include magnetic hard disks, random access memory (RAM), read-only memory (ROM), dynamic RAM (DRAM), synchronous dynamic RAM (SDRAM), ferroelectric RAM (FeRAM), magnetic RAM (MRAM), resistive RAM (RRAM), flash memory, phase change memory (PCM), and others. Memory devices may be volatile or non-volatile. Non-volatile memory, e.g., FeRAM, may maintain their stored logic state for extended periods of time even in the absence of an external power source. Volatile memory devices, e.g., DRAM, SRAM, may lose their stored state when disconnected from an external power source. Dynamic memory devices, e.g., DRAM, SDRAM, may lose a stored state over time unless they are periodically refreshed. 
     In some cases, a memory device (e.g., a DRAM device) may be configured to recognize a set of commands corresponding to unique instructions (e.g., read, write, refresh). For example, if a memory device receives a command, the memory device may execute the command according to the indicated instruction. Improving memory devices, generally, may include increasing memory cell density, increasing read/write speeds, increasing reliability, increasing data retention, reducing power consumption, or reducing manufacturing costs, among other metrics. Improving a memory device&#39;s operation based on received commands is desired. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    illustrates an example of a system that supports command block management as disclosed herein. 
         FIG.  2    illustrates an example of a memory sub-array that supports command block management as disclosed herein. 
         FIG.  3    illustrates an example of a system that supports command block management as disclosed herein. 
         FIGS.  4  through  7    illustrate process flows that support command block management as disclosed herein. 
         FIGS.  8  and  9    illustrate block diagrams for apparatuses that support command block management as disclosed herein. 
         FIGS.  10  through  14    illustrate a method or methods that support memory command verification as disclosed herein. 
     
    
    
     DETAILED DESCRIPTION 
     Memory devices may operate under various conditions as part of electronic apparatuses such as personal computers, wireless communication devices, servers, internet-of-things (IoT) devices, electronic components of automotive vehicles, and the like. In some cases, memory devices supporting applications for certain implementations (e.g., automotive vehicles, in some cases with autonomous or semi-autonomous driving capabilities) may be subject to increased reliability constraints. As such, memory devices (e.g., DRAM) for some applications may be expected to operate with a reliability subject to relatively higher industry specifications (e.g., higher reliability constraints). 
     Some memory devices may be configured to recognize a set of defined commands corresponding to unique instructions (e.g., read, write, refresh) or addresses (e.g., row address, column address). For example, if a memory device receives a defined command, the memory device may execute the command according to the indicated instruction and address. In some cases, there may be commands that are not defined for the memory device (e.g., commands that do not correspond to a defined instruction and/or defined address). That is, there may be commands or command sequences that do not correspond to a defined operation or set of operations. 
     For example, commands may be conveyed by the states of pins of the memory device, and a subset of the possible combinations of the pins may not correspond to defined operations for the memory device. In the case that a memory device receives an undefined command or command sequence, the response of the memory device may be variable or unknown. For example, a memory device may not have a defined operation associated with an undefined command and as such, may execute variable operations in response to the undefined command. In some cases, undefined commands leading to variable operations may leave the memory device susceptible to malicious attacks. That is, a command or series of commands may be sent to the memory device in order to cause the memory device to behave erratically. 
     Techniques for blocking undefined commands from execution at the memory device are described. For example, the memory device may determine whether a command is defined prior to decoding and executing the command. The memory device may identify a set of defined commands for the memory device. When the memory device receives a command or a sequence of commands, the memory device may determine whether each command of the received commands is defined by determining if each received command is absent or present within the set of defined commands. In the case that a received command is absent from the set of defined commands (e.g., the command is undefined), the memory device may block the command from being decoded for execution by the memory device. In one example, the memory device may activate a safe mode for the memory array associated with the detected undefined command. The safe mode may restrict the operation of the memory device (e.g., by limiting the type of commands executed, by limiting the portion of a memory array of the memory device for executing commands). Additionally or alternatively, the memory device may transmit a notification to a host device indicating the undefined command. Thus, the memory device may prevent the execution of undefined commands in order to improve the reliability of the memory device (e.g., by decreasing variable behavior of the memory device). 
     Features of the disclosure are initially described in the context of a memory system and device with reference to  FIGS.  1 ,  2 , and  3   . Features of the disclosure are described in the context of a process flow with reference to  FIGS.  4 ,  5 ,  6 , and  7   . These and other features of the disclosure are further illustrated by and described with reference to apparatus diagrams and flowcharts in  FIGS.  8 - 14    that relate to command block management. 
       FIG.  1    illustrates an example of a system  100  that utilizes one or more memory devices in accordance with aspects disclosed herein. The system  100  may include an external memory controller  105 , a memory device  110 , and a plurality of channels  115  coupling the external memory controller  105  with the memory device  110 . The system  100  may include one or more memory devices, but for ease of description the one or more memory devices may be described as a single memory device  110 . 
     The system  100  may include aspects of an electronic device, such as a computing device, a mobile computing device, a wireless device, or a graphics processing device. The system  100  may be an example of a portable electronic device. The system  100  may be an example of a computer, a laptop computer, a tablet computer, a smartphone, a cellular phone, a wearable device, an internet-connected device, or the like. The memory device  110  may be component of the system configured to store data for one or more other components of the system  100 . In some examples, the system  100  is configured for bi-directional wireless communication with other systems or devices using a base station or access point. In some examples, the system  100  is capable of machine-type communication (MTC), machine-to-machine (M2M) communication, or device-to-device (D2D) communication. 
     At least portions of the system  100  may be examples of a host device. Such a host device may be an example of a device that uses memory to execute processes such as a computing device, a mobile computing device, a wireless device, a graphics processing device, a computer, a laptop computer, a tablet computer, a smartphone, a cellular phone, a wearable device, an internet-connected device, some other stationary or portable electronic device, or the like. In some examples, system  100  is a graphics card. In some cases, the host device may refer to the hardware, firmware, software, or a combination thereof that implements the functions of the external memory controller  105 . In some cases, the external memory controller  105  may be referred to as a host or host device. 
     In some cases, the memory device  110  may be an independent device or component that is configured to be in communication with other components of the system  100  and provide physical memory addresses/space to potentially be used or referenced by the system  100 . In some examples, a memory device  110  may be configurable to work with at least one or a plurality of different types of systems  100 . Signaling between the components of the system  100  and the memory device  110  may be operable to support modulation schemes to modulate the signals, different pin designs for communicating the signals, distinct packaging of the system  100  and the memory device  110 , clock signaling and synchronization between the system  100  and the memory device  110 , timing conventions, and/or other factors. 
     The memory device  110  may be configured to store data for the components of the system  100 . In some cases, the memory device  110  may act as a slave-type device to the system  100  (e.g., responding to and executing commands provided by the system  100  through the external memory controller  105 ). Such commands may include an access command for an access operation, such as a write command for a write operation, a read command for a read operation, a refresh command for a refresh operation, or other commands. The memory device  110  may include two or more memory dice  160  (e.g., memory chips) to support a desired or specified capacity for data storage. The memory device  110  including two or more memory dice may be referred to as a multi-die memory or package (also referred to as multi-chip memory or package). 
     The system  100  may further include a processor  120 , a basic input/output system (BIOS) component  125 , one or more peripheral components  130 , and an input/output (I/O) controller  135 . The components of system  100  may be in electronic communication with one another using a bus  140 . 
     The processor  120  may be configured to control at least portions of the system  100 . The processor  120  may be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or it may be a combination of these types of components. In such cases, the processor  120  may be an example of a central processing unit (CPU), a graphics processing unit (GPU), a general purpose GPU (GPGPU), or a system on a chip (SoC), among other examples. 
     The BIOS component  125  may be a software component that includes a BIOS operated as firmware, which may initialize and run various hardware components of the system  100 . The BIOS component  125  may also manage data flow between the processor  120  and the various components of the system  100 , e.g., the peripheral components  130 , the I/O controller  135 , etc. The BIOS component  125  may include a program or software stored in read-only memory (ROM), flash memory, or any other non-volatile memory. 
     The peripheral component(s)  130  may be any input device or output device, or an interface for such devices, that may be integrated into or with the system  100 . Examples may include disk controllers, sound controller, graphics controller, Ethernet controller, modem, universal serial bus (USB) controller, a serial or parallel port, or peripheral card slots, such as peripheral component interconnect (PCI) or accelerated graphics port (AGP) slots. The peripheral component(s)  130  may be other components understood by those skilled in the art as peripherals. 
     The I/O controller  135  may manage data communication between the processor  120  and the peripheral component(s)  130 , input devices  145 , or output devices  150 . The I/O controller  135  may manage peripherals that are not integrated into or with the system  100 . In some cases, the I/O controller  135  may represent a physical connection or port to external peripheral components. 
     The input  145  may represent a device or signal external to the system  100  that provides information, signals, or data to the system  100  or its components. This may include a user interface or interface with or between other devices. In some cases, the input  145  may be a peripheral that interfaces with system  100  via one or more peripheral components  130  or may be managed by the I/O controller  135 . 
     The output  150  may represent a device or signal external to the system  100  configured to receive an output from the system  100  or any of its components. Examples of the output  150  may include a display, audio speakers, a printing device, or another processor on printed circuit board, and so forth. In some cases, the output  150  may be a peripheral that interfaces with the system  100  via one or more peripheral components  130  or may be managed by the I/O controller  135 . 
     The components of system  100  may be made up of general-purpose or special purpose circuitry designed to carry out their functions. This may include various circuit elements, for example, conductive lines, transistors, capacitors, inductors, resistors, amplifiers, or other active or passive elements, configured to carry out the functions described herein. 
     The memory device  110  may include a device memory controller  155  and one or more memory dice  160 . Each memory die  160  may include a local memory controller  165  (e.g., local memory controller  165 - a , local memory controller  165 - b , and/or local memory controller  165 -N) and a memory array  170  (e.g., memory array  170 - a , memory array  170 - b , and/or memory array  170 -N). A memory array  170  may be a collection (e.g., a grid) of memory cells, with each memory cell being configured to store at least one bit of digital data. Features of memory arrays  170  and/or memory cells are described in more detail with reference to  FIG.  2   . 
     The memory device  110  may be an example of a two-dimensional (2D) array of memory cells or may be an example of a three-dimensional (3D) array of memory cells. For example, a 2D memory device may include a single memory die  160 . A 3D memory device may include two or more memory dice  160  (e.g., memory die  160 - a , memory die  160 - b , and/or any number of memory dice  160 -N). In a 3D memory device, a plurality of memory dice  160 -N may be stacked on top of one another. In some cases, memory dice  160 -N in a 3D memory device may be referred to as decks, levels, layers, or dies. A 3D memory device may include any quantity of stacked memory dice  160 -N (e.g., two high, three high, four high, five high, six high, seven high, eight high). This may increase the number of memory cells that may be positioned on a substrate as compared with a single 2D memory device, which in turn may reduce production costs or increase the performance of the memory array, or both. In some 3D memory device, different decks may share at least one common access line such that some decks may share at least one of a word line, a digit line, and/or a plate line. 
     The device memory controller  155  may include circuits or components configured to control operation of the memory device  110 . As such, the device memory controller  155  may include the hardware, firmware, and software that enables the memory device  110  to perform commands and may be configured to receive, transmit, or execute commands, data, or control information related to the memory device  110 . The device memory controller  155  may be configured to communicate with the external memory controller  105 , the one or more memory dice  160 , or the processor  120 . In some cases, the memory device  110  may receive data and/or commands from the external memory controller  105 . For example, the memory device  110  may receive a write command indicating that the memory device  110  is to store certain data on behalf of a component of the system  100  (e.g., the processor  120 ) or a read command indicating that the memory device  110  is to provide certain data stored in a memory die  160  to a component of the system  100  (e.g., the processor  120 ). 
     The memory device  110  may store a set of defined commands corresponding to unique instructions (e.g., read, write, refresh) or addresses (e.g., row address, column address). In some cases, the memory device  110  may determine that a command (e.g., received from the external memory controller  105 ) is defined prior to executing the command at a memory array  170 . Further, the memory device  110  may block undefined commands (e.g., commands that do not correspond to a defined instruction and/or defined address) and by not decoding and/or executing undefined commands. In one example, the memory device  110  may activate a safe mode for a memory array  170  associated with the undefined command. The safe mode may restrict the execution of commands at a certain portion of the memory array  170  (e.g., a bank or banks associated with the undefined command). Additionally or alternatively, the safe mode may restrict the type of commands for execution (e.g., the safe mode may allow an execution of read commands while restricting an execution of write commands). In some examples, the memory device  110  may transmit a notification to the external memory controller  105  related to the undefined command. 
     In some cases, the device memory controller  155  may control operation of the memory device  110  described herein in conjunction with the local memory controller  165  of the memory die  160 . Examples of the components included in the device memory controller  155  and/or the local memory controllers  165  may include receivers for demodulating signals received from the external memory controller  105 , decoders for modulating and transmitting signals to the external memory controller  105 , logic, decoders, amplifiers, filters, or the like. 
     The local memory controller  165  (e.g., local to a memory die  160 ) may be configured to control operations of the memory die  160 . Also, the local memory controller  165  may be configured to communicate (e.g., receive and transmit data and/or commands) with the device memory controller  155 . The local memory controller  165  may support the device memory controller  155  to control operation of the memory device  110  as described herein. In some cases, the memory device  110  does not include the device memory controller  155 , and the local memory controller  165  or the external memory controller  105  may perform the various functions described herein. As such, the local memory controller  165  may be configured to communicate with the device memory controller  155 , with other local memory controllers  165 , or directly with the external memory controller  105  or the processor  120 . 
     The external memory controller  105  may be configured to enable communication of information, data, and/or commands between components of the system  100  (e.g., the processor  120 ) and the memory device  110 . The external memory controller  105  may act as a liaison between the components of the system  100  and the memory device  110  so that the components of the system  100  may not need to know the details of the memory device&#39;s operation. The components of the system  100  may present requests to the external memory controller  105  (e.g., read commands or write commands) that the external memory controller  105  satisfies. The external memory controller  105  may convert or translate communications exchanged between the components of the system  100  and the memory device  110 . In some cases, the external memory controller  105  may include a system clock that generates a common (source) system clock signal. In some cases, the external memory controller  105  may include a common data clock that generates a common (source) data clock signal. 
     In some cases, the external memory controller  105  or other component of the system  100 , or its functions described herein, may be implemented by the processor  120 . For example, the external memory controller  105  may be hardware, firmware, or software, or some combination thereof implemented by the processor  120  or other component of the system  100 . While the external memory controller  105  is depicted as being external to the memory device  110 , in some cases, the external memory controller  105 , or its functions described herein, may be implemented by a memory device  110 . For example, the external memory controller  105  may be hardware, firmware, or software, or some combination thereof implemented by the device memory controller  155  or one or more local memory controllers  165 . In some cases, the external memory controller  105  may be distributed across the processor  120  and the memory device  110  such that portions of the external memory controller  105  are implemented by the processor  120  and other portions are implemented by a device memory controller  155  or a local memory controller  165 . Likewise, in some cases, one or more functions ascribed herein to the device memory controller  155  or local memory controller  165  may in some cases be performed by the external memory controller  105  (either separate from or as included in the processor  120 ). 
     The components of the system  100  may exchange information with the memory device  110  using a plurality of channels  115 . In some examples, the channels  115  may enable communications between the external memory controller  105  and the memory device  110 . Each channel  115  may include one or more signal paths or transmission mediums (e.g., conductors) between terminals associated with the components of system  100 . For example, a channel  115  may include a first terminal including one or more pins or pads at external memory controller  105  and one or more pins or pads at the memory device  110 . A pin may be an example of a conductive input or output point of a device of the system  100 , and a pin may be configured to act as part of a channel. In some cases, a pin or pad of a terminal may be part of to a signal path of the channel  115 . Additional signal paths may be coupled with a terminal of a channel for routing signals within a component of the system  100 . For example, the memory device  110  may include signal paths (e.g., signal paths internal to the memory device  110  or its components, such as internal to a memory die  160 ) that route a signal from a terminal of a channel  115  to the various components of the memory device  110  (e.g., a device memory controller  155 , memory dice  160 , local memory controllers  165 , memory arrays  170 ). 
     Channels  115  (and associated signal paths and terminals) may be dedicated to communicating specific types of information. In some cases, a channel  115  may be an aggregated channel and thus may include multiple individual channels. For example, a data channel  190  may be ×4 (e.g., including four signal paths), ×8 (e.g., including eight signal paths), ×16 (including sixteen signal paths), and so forth. 
     In some cases, the channels  115  may include one or more command and address (CA) channels  186 . The CA channels  186  may be configured to communicate commands between the external memory controller  105  and the memory device  110  including control information associated with the commands (e.g., address information). For example, the CA channel  186  may include a read command with an address of the desired data. In some cases, the CA channels  186  may be registered on a rising clock signal edge and/or a falling clock signal edge. In some cases, a CA channel  186  may include eight or nine signal paths. 
     In some cases, the channels  115  may include one or more clock signal (CK) channels  188 . The CK channels  188  may be configured to communicate one or more common clock signals between the external memory controller  105  and the memory device  110 . Each clock signal may be configured to oscillate between a high state and a low state and coordinate the actions of the external memory controller  105  and the memory device  110 . In some cases, the clock signal may be a differential output (e.g., a CK_t signal and a CK_c signal) and the signal paths of the CK channels  188  may be configured accordingly. In some cases, the clock signal may be single ended. In some cases, the clock signal may be a 1.5 GHz signal. A CK channel  188  may include any number of signal paths. In some cases, the clock signal CK (e.g., a CK_t signal and a CK_c signal) may provide a timing reference for command and addressing operations for the memory device  110 , or other system-wide operations for the memory device  110 . The clock signal CK therefore may be variously referred to as a control clock signal CK, a command clock signal CK, or a system clock signal CK. The system clock signal CK may be generated by a system clock, which may include one or more hardware components (e.g., oscillators, crystals, logic gates, transistors, or the like). 
     In some cases, the channels  115  may include one or more data (DQ) channels  190 . The data channels  190  may be configured to communicate data and/or control information between the external memory controller  105  and the memory device  110 . For example, the data channels  190  may communicate information (e.g., bi-directional) to be written to the memory device  110  or information read from the memory device  110 . The data channels  190  may communicate signals that may be modulated using a variety of different modulation schemes (e.g., NRZ, PAM4). 
     In some cases, the channels  115  may include one or more other channels  192  that may be dedicated to other purposes. These other channels  192  may include any number of signal paths. 
     In some cases, the other channels  192  may include one or more write clock signal (WCK) channels. While the ‘W’ in WCK may nominally stand for “write,” a write clock signal WCK (e.g., a WCK_t signal and a WCK_c signal) may provide a timing reference for access operations generally for the memory device  110  (e.g., a timing reference for both read and write operations). Accordingly, the write clock signal WCK may also be referred to as a data clock signal WCK. The WCK channels may be configured to communicate a common data clock signal between the external memory controller  105  and the memory device  110 . The data clock signal may be configured to coordinate an access operation (e.g., a write operation or read operation) of the external memory controller  105  and the memory device  110 . In some cases, the write clock signal may be a differential output (e.g., a WCK_t signal and a WCK_c signal) and the signal paths of the WCK channels may be configured accordingly. A WCK channel may include any number of signal paths. The data clock signal WCK may be generated by a data clock, which may include one or more hardware components (e.g., oscillators, crystals, logic gates, transistors, or the like). 
     In some cases, the other channels  192  may include one or more error detection code (EDC) channels. The EDC channels may be configured to communicate error detection signals, such as checksums, to improve system reliability. An EDC channel may include any number of signal paths. 
     The channels  115  may couple the external memory controller  105  with the memory device  110  using a variety of different architectures. Examples of the various architectures may include a bus, a point-to-point connection, a crossbar, a high-density interposer such as a silicon interposer, or channels formed in an organic substrate or some combination thereof. For example, in some cases, the signal paths may at least partially include a high-density interposer, such as a silicon interposer or a glass interposer. 
     Signals communicated over the channels  115  may be modulated using a variety of different modulation schemes. In some cases, a binary-symbol (or binary-level) modulation scheme may be used to modulate signals communicated between the external memory controller  105  and the memory device  110 . A binary-symbol modulation scheme may be an example of a M-ary modulation scheme where M is equal to two. Each symbol of a binary-symbol modulation scheme may be configured to represent one bit of digital data (e.g., a symbol may represent a logic 1 or a logic 0). Examples of binary-symbol modulation schemes include, but are not limited to, non-return-to-zero (NRZ), unipolar encoding, bipolar encoding, Manchester encoding, pulse amplitude modulation (PAM) having two symbols (e.g., PAM2), and/or others. 
     In some cases, a multi-symbol (or multi-level) modulation scheme may be used to modulate signals communicated between the external memory controller  105  and the memory device  110 . A multi-symbol modulation scheme may be an example of a M-ary modulation scheme where M is greater than or equal to three. Each symbol of a multi-symbol modulation scheme may be configured to represent more than one bit of digital data (e.g., a symbol may represent a logic 00, a logic 01, a logic 10, or a logic 11). Examples of multi-symbol modulation schemes include, but are not limited to, PAM4, PAM8, etc., quadrature amplitude modulation (QAM), quadrature phase shift keying (QPSK), and/or others. A multi-symbol signal or a PAM4 signal may be a signal that is modulated using a modulation scheme that includes at least three levels to encode more than one bit of information. Multi-symbol modulation schemes and symbols may alternatively be referred to as non-binary, multi-bit, or higher-order modulation schemes and symbols. 
       FIG.  2    illustrates an example of a memory sub-array  200  in accordance with various examples of the present disclosure. The memory sub-array  200  may be an example of at least a portion of the memory dice  160  described with reference to  FIG.  1   . In some cases, the memory sub-array  200  may be referred to as a memory die, memory chip, a memory device, or an electronic memory apparatus. For example, a memory device such as a memory chip may include multiple instances of sub-array  200 , with additional row, address, bank, or bank group decoding used to select one or more sub-arrays from the multiple instances for access operations. The memory sub-array  200  may include one or more memory cells  205  that are programmable to store different logic states. Each memory cell  205  may be programmable to store two or more states. For example, the memory cell  205  may be configured to store one bit of digital logic at a time (e.g., a logic 0 and a logic 1). In some cases, a single memory cell  205  (e.g., a multi-level memory cell) may be configured to store more than one bit of digit logic at a time (e.g., a logic 00, logic 01, logic 10, or a logic 11). 
     A memory cell  205  may store a charge representative of the programmable states in a capacitor. DRAM architectures may include a capacitor that includes a dielectric material to store a charge representative of the programmable state. In other memory architectures, other storage devices and components are possible. For example, nonlinear dielectric materials may be employed. 
     Operations such as reading and writing may be performed on memory cells  205  by activating or selecting access lines such as a word line  210  and/or a digit line  215 . In some cases, digit lines  215  may also be referred to as bit lines. References to access lines, word lines and digit lines, or their analogues, are interchangeable without loss of understanding or operation. Activating or selecting a word line  210  or a digit line  215  may include applying a voltage to the respective line or configuring a multiplexer to map the line to a given signal. 
     The memory sub-array  200  may include the access lines (e.g., the word lines  210  and the digit lines  215 ) arranged in a grid-like pattern. Memory cells  205  may be positioned at intersections of the word lines  210  and the digit lines  215 . By biasing a word line  210  (e.g., applying a voltage to the word line  210 ), a memory cell  205  may be accessed via the digit line  215  at their intersection. 
     Accessing the memory cells  205  may be controlled through a row decoder  220  or a column decoder  225 . For example, a row decoder  220  may receive a row address from the local memory controller  260  and activate a word line  210  based on the received row address. A column decoder  225  may receive a column address from the local memory controller  260  and may select a digit line  215  based on the received column address. For example, the memory sub-array  200  may include multiple word lines  210 , labeled WL_ 1  through WL_M, and multiple digit lines  215 , labeled DL_ 1  through DL_N, where M and N depend on the size of the memory array. Thus, by activating a word line  210 , e.g., WL_ 1 , the memory cells  205  in a given row may be accessed. The digit lines  215  (e.g., DL_ 1 , . . . , DL_N) carry the data for writing or reading from the memory cells in the row. The intersection of a word line  210  and a digit line  215 , in either a two-dimensional or three-dimensional configuration, may be referred to as an address of a memory cell  205 . 
     The memory cell  205  may include a logic storage component, such as capacitor  230  and a switching component  235 . The capacitor  230  may be an example of a dielectric capacitor or a ferroelectric capacitor. A first node of the capacitor  230  may be coupled with the switching component  235  and a second node of the capacitor  230  may be coupled with a voltage source  240 . In some cases, the voltage source  240  may be the cell plate reference voltage, such as Vpl, or may be ground, such as Vss. In some cases, the voltage source  240  may be an example of a plate line coupled with a plate line driver. The switching component  235  may be an example of a transistor or any other type of switch device that selectively establishes or de-establishes electronic communication between two components. 
     Selecting or deselecting the memory cell  205  may be accomplished by activating or deactivating the switching component  235 . The capacitor  230  may be in electronic communication with the digit line  215  using the switching component  235 . For example, the capacitor  230  may be isolated from digit line  215  when the switching component  235  is deactivated, and the capacitor  230  may be coupled with digit line  215  when the switching component  235  is activated. In some cases, the switching component  235  is a transistor and its operation may be controlled by applying a voltage to the transistor gate, where the voltage differential between the transistor gate and transistor source may be greater or less than a threshold voltage of the transistor. In some cases, the switching component  235  may be a p-type transistor or an n-type transistor. The word line  210  may be in electronic communication with the gate of the switching component  235  and may activate/deactivate the switching component  235  based on a voltage being applied to word line  210 . 
     A word line  210  may be a conductive line in electronic communication with a memory cell  205  that is used to perform access operations on the memory cell  205 . In some architectures, the word line  210  may be in electronic communication with a gate of a switching component  235  of a memory cell  205  and may be configured to control the switching component  235  of the memory cell. In some architectures, the word line  210  may be in electronic communication with a node of the capacitor of the memory cell  205  and the memory cell  205  may not include a switching component. 
     A digit line  215  may be a conductive line that connects the memory cell  205  with a sense component  245 . In some architectures, the memory cell  205  may be selectively coupled with the digit line  215  during portions of an access operation. For example, the word line  210  and the switching component  235  of the memory cell  205  may be configured to couple and/or isolate the capacitor  230  of the memory cell  205  and the digit line  215 . In some architectures, the memory cell  205  may be in electronic communication (e.g., constant) with the digit line  215 . 
     The sense component  245  may be configured to detect a state (e.g., a charge) stored on the capacitor  230  of the memory cell  205  and determine a logic state of the memory cell  205  based on the stored state. The charge stored by a memory cell  205  may be extremely small, in some cases. As such, the sense component  245  may include one or more sense amplifiers to amplify the signal output by the memory cell  205 . The sense amplifiers may detect small changes in the charge of a digit line  215  during a read operation and may produce signals corresponding to a logic state 0 or a logic state 1 based on the detected charge. During a read operation, the capacitor  230  of memory cell  205  may output a signal (e.g., via charge sharing) to its corresponding digit line  215 . The signal may cause a voltage of the digit line  215  to change. The sense component  245  may be configured to compare the signal received from the memory cell  205  across the digit line  215  to a reference signal  250  (e.g., reference voltage). The sense component  245  may determine the stored state of the memory cell  205  based on the comparison. For example, in binary-signaling, if digit line  215  has a higher voltage than the reference signal  250 , the sense component  245  may determine that the stored state of memory cell  205  is a logic 1 and, if the digit line  215  has a lower voltage than the reference signal  250 , the sense component  245  may determine that the stored state of the memory cell  205  is a logic 0. The sense component  245  may include amplifiers (e.g., transistor amplifiers) to detect and amplify a difference in the signals. The detected logic state of memory cell  205  may be output through column decoder  225  as output  255 . In some cases, the aspects of sense component  245  may be part of another component (e.g., a column decoder  225 , row decoder  220 ). In some cases, the sense component  245  may be in electronic communication with the row decoder  220  or the column decoder  225 . 
     The local memory controller  260  may control the operation of memory cells  205  through the various components (e.g., row decoder  220 , column decoder  225 , and sense component  245 ). The local memory controller  260  may be an example of the local memory controller  165  described with reference to  FIG.  1   . In some cases, aspects of the row decoder  220 , column decoder  225 , or sense component  245  may be co-located with the local memory controller  260 . The local memory controller  260  may be configured to receive commands and/or data from an external memory controller  105  (or a device memory controller  155  described with reference to  FIG.  1   ) and translate the commands and/or data into information that can be used by the memory sub-array  200 . 
     The local memory controller  260  may determine whether received commands are defined prior to translating the commands into information that can be used by the memory sub-array  200 . That is, the local memory controller  260  may compare received commands to a set of defined commands. In the event that the received command is included in the set of defined commands, the local memory controller may translate the commands into information that can be used by the memory sub-array  200 . Alternatively, in the event that the received command is not included in the set of defined commands (e.g., the received command is undefined/invalid), the local memory controller  260  may block the command from being translated and propagated to the memory sub-array  200 . In one example, the local memory controller  260  may activate a safe mode for the memory sub-array  200  associated with the undefined command. The safe mode may restrict the execution of commands at a certain portion of the sub-array  200  (e.g., a bank or banks associated with the undefined command). Additionally or alternatively, the safe mode may restrict the type of commands for execution (e.g., the safe mode may allow an execution of read commands while restricting an execution of write commands). Further, the local memory controller  260  may transmit a notification a host device (e.g., an external memory controller  105  as described with reference to  FIG.  1   ) related to the undefined command. 
     The local memory controller  260  may further be configured to perform one or more operations on the memory sub-array  200 , and communicate data from the memory sub-array  200  to the external memory controller  105  (or the device memory controller  155 ) in response to performing the one or more operations. The local memory controller  260  may generate row and column address signals to activate the target word line  210  and select the target digit line  215 . The local memory controller  260  may also generate and control various voltages or currents used during the operation of the memory sub-array  200 . In general, the amplitude, shape, or duration of an applied voltage or current discussed herein may be adjusted or varied and may be different for the various operations discussed in operating the memory sub-array  200 . 
     In some cases, the local memory controller  260  may be configured to perform a write operation (e.g., a programming operation) on one or more memory cells  205  of the memory sub-array  200 . During a write operation, a memory cell  205  of the memory sub-array  200  may be programmed to store a desired logic state. In some cases, a plurality of memory cells  205  may be programmed during a single write operation. The local memory controller  260  may identify a target memory cell  205  on which to perform the write operation. The local memory controller  260  may identify a target word line  210  and a target digit line  215  in electronic communication with the target memory cell  205  (e.g., the address of the target memory cell  205 ). The local memory controller  260  may activate the target word line  210  (e.g., applying a voltage to the word line  210 ), to access a row including the target memory cell  205 . The local memory controller  260  may apply a specific signal (e.g., voltage) to the digit line  215  during the write operation to store a specific state (e.g., charge) in the capacitor  230  of the memory cell  205 , the specific state (e.g., charge) may be indicative of a desired logic state. 
     In some cases, the local memory controller  260  may be configured to perform a read operation (e.g., a sense operation) on one or more memory cells  205  of the memory sub-array  200 . During a read operation, the logic state stored in a memory cell  205  of the memory sub-array  200  may be determined. In some cases, a plurality of memory cells  205  may be sensed during a single read operation. The local memory controller  260  may identify a target memory cell  205  on which to perform the read operation. The local memory controller  260  may identify a target word line  210  and a target digit line  215  in electronic communication with the target memory cell  205  (e.g., the address of the target memory cell  205 ). The local memory controller  260  may activate the target word line  210  (e.g., applying a voltage to the word line  210 ), to access a row including the target memory cell  205 . The target memory cell  205  may transfer a signal to the sense component  245  in response to biasing the access lines. The sense component  245  may amplify the signal. The local memory controller  260  may fire the sense component  245  (e.g., latch the sense component) and thereby compare the signal received from the memory cell  205  to the reference signal  250 . Based on that comparison, the sense component  245  may determine a logic state that is stored on the memory cell  205 . The local memory controller  260  may communicate the logic state stored on the memory cell  205  to the external memory controller  105  (or the device memory controller  155 ) as part of the read operation (e.g., by selecting data read from digit lines  215  using column decoder  225 ). 
     The row access logic  265  and the column access logic  275  may determine a subset of the array corresponding to the target memory cell  205 . That is, the row access logic  265  and the column access logic  275  may be configured to determine the word line or lines  210  activated during the read operation and the digit line or lines  215  carrying the data associated with the read operation. The row access logic  265  and the column access logic  275  may transmit an indication of the determined subset of the array (e.g., to a verifier as discussed herein). In some examples, the indication of the subset of the array may indicate the subset along one or more dimensions of the array. For example, the indication of the subset of the array may indicate the word line or lines  210  being activated during the read operation (e.g., a row MAT indication). Additionally or alternatively, the indication of the subset of the array may indicate the digit line or lines  215  selected during the read operation (e.g., a column MAT indication). 
     In some memory architectures, accessing the memory cell  205  may degrade or destroy the logic state stored in a memory cell  205 . For example, a read operation performed in DRAM architectures may partially or completely discharge the capacitor of the target memory cell. The local memory controller  260  may perform a re-write operation or a refresh operation to return the memory cell to its original logic state. The local memory controller  260  may re-write the logic state to the target memory cell after a read operation. In some cases, the re-write operation may be considered part of the read operation. Additionally, activating a single access line, such as a word line  210 , may disturb the state stored in some memory cells in electronic communication with that access line. Thus, a re-write operation or refresh operation may be performed on one or more memory cells that may not have been accessed. 
       FIG.  3    illustrates an example of a system  300  that supports techniques for command block management. The system  300  may include one or more components described herein with reference to  FIGS.  1  and  2   . For example, the system  300  may include a host device  305 , which may be an example of the external memory controller  105  as described with reference to  FIG.  1    and a memory device  310 , which may be an example of the memory device  110 , the memory dice  160 , or the memory die  200  as described with reference to  FIGS.  1  and  2   . The memory device  310  may include a memory array  370 , which may be an example of the memory arrays  170  as described with reference to  FIG.  1   . The memory device  310  may also include valid command circuitry  325 , gate  345 , mode registers  380 , and event log registers  335 . 
     Host device  305  may send commands to memory device  310  via a channel  320 , which may be an example of a channel  115  or CA channel  186  as discussed with reference to  FIG.  1   . The memory device  310  may receive the commands at memory pins  315  which may, in some cases, be coupled with an input buffer. The commands may include individual commands (e.g., individual read or write commands), or burst commands (multiple sequential commands). The command or commands may be transmitted from the memory pins  315  (or input buffers coupled with the memory pins  315 ) to the valid command circuitry  325  via bus  330 . The command or commands received from the host device  305  may be propagated through the valid command circuitry  325  to the gate  345 . In some cases, the valid command circuitry  325  may cause the gate  345  to propagate defined commands (e.g., commands that are known by the memory device  310 ) to the decoder  360  and block commands (e.g., not propagating commands to the decoder  360 ) that are not defined. In this way, the memory device  310  may prevent undefined commands from being executed, thus increasing a reliability of the memory device  310 . 
     A defined command may be a command associated with a defined instruction (e.g., a read instruction, a write instruction, a refresh instruction, etc.) and/or a defined address (e.g., row address, column address). In some cases, there may be one or more possible commands that may not be defined for the memory device  310 . For example, a command may be indicated by three bits (e.g., received via three memory pins  315 ) such that there may be eight different possible bit combinations that the memory device  310  may receive. However, the memory device  310  may have just five defined commands (e.g., five of the eight combinations are defined, each corresponding to one of five distinct instructions). That is, there may be three possible received commands that may not be associated with a defined instruction. In some cases, a number of defined addresses (e.g., addresses corresponding to a location of the memory array  370 ) may be based on the size of the memory array  370 . These numbers are exemplary and for illustrative clarity only, and it is to be understand that a command may be indicated by any number of bits and received over any number of pins, including via any order of signaling (e.g., binary or non-binary signaling). 
     The valid command circuitry  325  may determine whether a received command is included in a set of commands that are defined for the memory device  310 . The memory device  310  may store a set of defined commands. In a first example, the set of defined commands may be a preconfigured set that is fixed by a vendor (e.g., during assembly) such as a DRAM vendor. The preconfigured set of defined commands may be non-programmable (e.g., hard-wired or stored in Read Only Memory (ROM)) or one-time-programmable (OTP) (e.g., stored in one or more fuses or anti-fuses or one or more memory OTP memory). In a second example, the set of defined commands may programmable after assembly (e.g., by the host  305 , by the original equipment manufacturer). In this example, the memory device  310  may receive the set of valid commands from the host device  305  and may store the set of valid commands in a memory (e.g., register, volatile memory, or non-volatile memory). The valid command circuitry  325  may utilize circuitry (e.g., a look-up table (LUT), a simplified processor circuitry implementing a logic function) to determine whether the received command is within the set of defined commands. In some cases, the valid command circuitry  325  may determine whether a sequence of commands is part of a defined set of command sequences. 
     The valid command circuitry  325  may transmit a pass/block signal  355  to the gate  345  based on whether the command received from the host  305  is within the defined set of commands. For example, the valid command circuitry  325  may set the pass/block signal  355  to a first logic state to signal the gate  345  to propagate the command and may set the pass/block signal  355  to a second logic state to signal the gate  345  to block the command. The gate  345  may be a combination of logical gates or pass gates. For example, the gate  345  may set an instruction of internal command bus  365  to an instruction of the received command  330  when it identifies the first logic state on the pass or block signal  355  and to a no-operation (NOP) instruction when it identifies the second logic state on the pass or block signal  355 . 
     In some cases, the valid command circuitry  325  may be different than decoder  360 . For example, decoder  360  may be a custom logic or transistor level circuit, while valid command circuitry  325  may be a synthesized logic block (e.g., synthesized from a hardware description language). In some cases, the decoder  360  may use switched logic gates while valid command circuitry  325  uses static combinatorial logic gates. In some cases, the decoder  360  may map virtual addresses to physical addresses within memory array  370 , while valid command circuitry  325  may determine if the virtual addresses are within a valid range of addresses, but may not map the addresses to physical addresses of memory array  370 . 
     The valid command circuitry  325  may transmit an indication of an invalid command  340  (e.g., a command that is not included within a set of defined commands) to the event log registers  335 . The event log registers  335  may store the indication of the invalid command  340 . In some cases, the event log registers  335  may further store the invalid command itself. In the event that the memory device  310  receives a sequence of commands from the host device  305 , the event log registers  335  may store each of the commands of the sequence of commands that is invalid. In some instances, the valid command circuitry  325  may transmit the indication of the invalid command  340  to the mode registers  380 . 
     The event log registers  335  may record a number of invalid commands received from the host device  305 . For example, the event log registers  335  may include a counting register for storing a number of invalid commands. Here, the counting register may increment a stored value when the event log registers  335  receive the indication of the invalid command  340  from the valid command circuitry  325 . In some cases, the number of recorded invalid commands may be based on a number of invalid commands indicated by the valid command circuitry  325  within a given time frame. The number of recorded invalid commands may be compared to a threshold. In some cases, if the number of recorded invalid commands satisfies the threshold (e.g., the number of recorded invalid commands is greater than or equal to the threshold), the event log register  335  may transmit an indication of the satisfied threshold to the mode registers  380  via bus  385 . The memory device  310  may utilize the threshold to determine a potential malicious attack. That is, when the threshold is met, the memory device  310  may determine that the number of invalid commands may be associated with a malicious attack. The threshold may be preconfigured (e.g., set during assembly) or programmable (e.g., programmable by a host device  305 ). The threshold may be one command (e.g., a single invalid command may trigger the indication of the satisfied threshold), or multiple invalid commands, in some cases. 
     The mode registers  380  may indicate a mode of operation for the memory device  310 . That is, the memory device  310  may operate according to modes of operation, which may include an access mode and a safe mode. In the access mode, the memory device  310  may execute commands (e.g., the defined commands) received from host device  305  at the indicated portion of memory array  370 . However, during the safe mode, the memory device  310  may apply a restriction of access to at least a portion of the memory array  370 . For example, in the safe mode the memory device  310  may block commands to one or more portions (e.g., rows, columns, sub-arrays, banks, bank groups) of the memory array  370  subject to the restriction of access. In some other examples, the memory device  310  may not execute any defined commands during the safe mode. In some other examples, the memory device  310  may not execute certain types of defined commands during the safe mode (e.g., the memory device  310  may execute read commands during a safe mode, but may not execute other types of commands). In some other examples, the memory device  310  may refresh some (e.g., certain rows, sub-arrays, banks, bank groups) or all of the memory array  370  during the safe mode (e.g., autonomously or automatically). In some instances, the mode registers  380  may indicate the safe mode based on receiving the indication that the number of recorded invalid commands satisfies the threshold (e.g., from the event log registers  335 ). In some other instances, the mode registers  380  may indicate the safe mode based on receiving the indication of the invalid command  340  from the valid command circuitry  325 . For example, the mode registers  380  may set a safe mode register to a logic ‘1’ indicating the safe mode. During the safe mode, the memory device  310  may operate the portion of the memory array associated with the safe mode (e.g., the rows, sub-arrays, bank(s), or bank groups operating according to the safe mode) in a self-refresh mode. 
     The memory device  310  may maintain the safe mode for a predetermined period of time (e.g., time period or number of clocks), or until receiving a command from the host device  305  to return to the access mode. The command may indicate a reset procedure, which may transition the memory device  310  from the safe mode to the access mode. The command to reset to the access mode may include a single command, or a sequence of commands that may be known by host device  305  and by the memory device  310 . The sequence may act as a guard key. Here, host device  305  may transmit the sequence of commands (e.g., guard key) to memory device  310 . The memory device  310  (e.g., at the decoder  360  or valid command circuitry  325 ) may recognize the sequence of commands and transition the portion of the memory array  370  from the safe mode to the access mode. 
     The event log registers  335  may provide a feedback to the host device  305  related to the invalid command. In some cases, the feedback may include an indication of the invalid command. Additionally or alternatively, the feedback may include the invalid command received at the memory pins  315 . For example, the memory device  310  may include the invalid command in the feedback in response to the host device  305  transmitting a request to the memory device  305  for an indication of the invalid command received at the memory pins  315 . In another example, the feedback may include an indication that the threshold has been satisfied (e.g., an indication that the memory device  310  is operating according to a safe mode). 
     The memory device  310  may send the feedback to the host device  305  via path  395 . In some cases, path  395  may include a distinct set of feedback pins or sideband pins (e.g., separate from memory pins  315 ). In some other cases, path  395  may include the memory pins  315 . For example, the indication of the invalid command may be sent by the same path (e.g., including channel  320  and memory pins  315 ) as the host  305  uses to indicate commands to the memory device  310 . When the memory device  310  sends the feedback to the host device via pins (e.g., via feedback pins, via memory pins  315 ), a first pin may indicate an invalid command while one or more other pins may transmit the received invalid command. In some other cases, the host device  305  may poll one or more of the event log registers  335 . For example, the host device  305  may poll a register that indicates that the memory device  310  received an invalid command. In another example, the host device  305  may poll a register (e.g., a counting register) to determine a number of invalid commands that the memory device  310  has received within a time window. 
     The host device  305  may respond to the received feedback. In some cases, the host device  305  may determine to transmit one or more commands based on the feedback relating to the invalid command. For example, the feedback may indicate that the memory device  310  has entered into a safe mode of operation. Here, the host device  305  may transmit a command or commands as part of a reset procedure to transition the memory device  310  from the safe mode to the access mode. In another example, the host device  305  may determine that a desired command was not executed (e.g., due to the command not being defined at the memory device  310 ) and determine to re-transmit the same command, or transmit a different command or command sequence for execution. Additionally or alternatively, the host device  305  may transmit a command sequence to the memory device  310  to add a command to the set of defined commands. For example, the host device  305  may transmit a command sequence to add the desired command to the set of defined commands at the memory device  310 . 
     In the case that the received command is defined at the memory device  305 , the valid command circuitry may determine that a received command is included in the set of defined commands. Here, the valid command circuitry  325  may indicate via the pass/block signal  355  for the gate  345  to propagate the received command as internal command  365  to the decoder  360 . The decoder  360  may receive the internal command  365  and determine an instruction and an address associated with the defined command. After decoding the command, the decoder  360  may subsequently indicate the instruction and the address to the memory array  370  (e.g., via the bus  375 ). The address sent to the memory array  370  may be, for example, a physical address of the memory array  370  including row, column, sub-array, bank, or bank group for the instruction (e.g., row matrix (MAT) and/or column MAT). In some cases, the mode registers  380  may further indicate a portion of the memory array associated with the safe mode of operation. In some other cases, the mode registers  380  may indicate a type of command that is restricted during the safe mode of operation. 
     The memory array  370  may determine a mode of operation for the memory device  310  by polling one or more mode registers  380 . The mode registers  380  may indicate the mode of operation to the memory array  370  via bus  390 . For example, the memory array  370  may read a value stored at the mode registers  380  to determine whether the memory device  310  is operating according to an access mode or a safe mode. Additionally or alternatively, the decoder  360  may poll the mode registers to determine the mode of operation for the memory device  310 . Here, the decoder  360  may adjust the instruction and/or the address sent to the memory array  370  based on the determined mode of operation. For example, the decoder may not transmit, to the memory array  370 , the instruction and address if the instruction and/or address are restricted as part of the safe mode of operation. Alternatively, the valid command circuitry  325  may poll the mode registers  380  to determine whether a received command is executable in light of a current mode of operation. Here, the valid command circuitry  325  may not propagate commands that are restricted as part of the safe mode of operation. 
     If the memory device  310  is operating according to an access mode, the memory array  370  may access the indicated address and according to the indicated instruction (e.g., an instruction corresponding to a read instruction, a refresh instruction, a write instruction). If the memory device  310  is operating according to a safe mode, the valid command circuitry  325 , the decoder  360 , or the memory array  310  may determine if the indicated address corresponds to a portion of the memory array  370  that is associated with a restriction of access. If the indicated address does correspond to the portion of the memory array  370  that is operating within the restricted access mode, the defined command may not be executed. If the indicated address does not correspond to the portion of the memory array  370  that is associated with a restriction of access, the defined command may be executed. Additionally or alternatively, if the memory device  310  is operating according to a safe mode, the memory array  310  may determine if the indicated instruction corresponds to an instruction restricted by the safe mode of operation. If the indicated instruction does correspond to a restricted instruction, the defined command may not be executed. If the indicated instruction does not correspond to a restricted instruction, the defined command may be executed. 
       FIG.  4    shows an example diagram of a process flow  400  that supports techniques for command block management. The features of process flow  400  may be implemented or performed by a memory device (e.g., the memory device  110 , the memory dice  160 , the memory die  200 , or the memory device  310  described with reference to  FIGS.  1  through  3   ) or a component of a memory device such as the device memory controller  155 , the local memory controllers  165 , the local memory controller  260 , as described with reference to  FIGS.  1  and  2   . 
     At block  405 , circuitry associated with a memory device may receive a command from a host device. The circuitry may correspond to, for example, portions of the memory device  310  such as the memory pins  315  and a corresponding input buffer, valid command circuitry  325 , gate  345 , decoder  360 , or registers of  FIG.  3   . In some cases, the memory device may be operating according to an access mode at  405  (e.g., the memory device may execute each valid command received from a host device). 
     At block  410 , the circuitry may determine whether the received command is valid. A valid command may correspond to a command included in a set of defined commands. The circuitry may compare the received command with the set of defined commands. In the case that the received command is included in the set of defined commands (e.g., the command is valid), the circuitry may proceed to block  435 . At block  435 , the circuitry may execute the command according to an instruction and address indicated by the command. Then, the circuitry may continue to operate in an access mode (e.g., at block  440 ). Alternatively, when the circuitry determines that the received command is absent from the set of defined commands at block  40  (e.g., the command is invalid), the circuitry may proceed to block  415 . 
     At block  415 , the circuitry may block the command. For example, the circuitry may prevent the command from being sent to a decoder (e.g., to be decoded into an instruction and an address and subsequently executed at a memory array associated with the memory device). In some cases, the circuitry may block the command by transmitting a block signal to a gate (e.g., as discussed with reference to  FIG.  3   ). The block signal may act as a deactivation signal for the gate, or may set the gate to propagate a known command (e.g., NOP) to the decoder thus preventing the circuitry from transmitting the invalid command to a decoder. After the circuitry blocks the command, the circuitry may proceed to either block  420 ,  425 , and/or  440 . 
     At block  420 , the circuitry may transmit a notification regarding the invalid command to a host device (e.g., host device  305  as discussed with reference to  FIG.  3   ). The notification may include an indication that an invalid command was received (and subsequently blocked). In another example, the notification may include the received command that was blocked. Additionally or alternatively, the notification may include an indication that a threshold was satisfied. The threshold may correspond to a number of invalid commands (e.g., received within a configured time window) that may be indicative of a malicious attack. Therefore, the notification may indicate that the threshold has been met (e.g., the number of invalid commands received during the configured time window satisfied the threshold). In some other cases, the notification may include the mode of operation of the memory device (e.g., an access mode, a safe mode) or a restriction associated with the mode of operation (e.g., a bank or sub-array that is restricted). After the circuitry transmits the notification to the host device, the circuitry may proceed to either block  440  (e.g., operating according to the access mode operation) or to block  425 . 
     At  425 , the circuitry may optionally transition the memory device from an access mode to a safe mode operation. In some cases, the circuitry may transition the memory device to a safe mode operation in the event that the circuitry detects that the threshold number of invalid commands has been met. That is, the circuitry may detect a potentially malicious attack to the memory device and may switch to a safe mode operation to restrict the operation of the memory device (e.g., limit the instructions to certain types of command, limit the portion/banks of a memory array for executing commands). After the circuitry transitions the memory device to a safe mode operation, the circuitry may proceed to block  430 . 
     At block  430 , the circuitry may identify whether a reset procedure has been executed. The reset procedure may be specific to the portions of the memory array that have been transitioned to a safe mode operation. A reset procedure may transition the memory array (or portions of the memory array) from the safe mode to the access mode. When the circuitry determines that the reset procedure has been executed, the circuitry may proceed to block  440 , where the circuitry may transition the memory device (or portions of the memory device that had been operating according to the safe mode) into the access mode. Alternatively, when the circuitry determines that the reset procedure has not been executed, the circuitry may proceed to block  425  (e.g., the circuitry may continue to block certain types of access commands or the portion(s) of the memory array that are operating according to a safe mode). 
       FIG.  5    illustrates an example of a process flow  500  that supports techniques for command block management. In some examples, process flow  500  may be implemented by aspects of the systems  100  and  300 , memory die  200 , and process flow  400 . The process flow  500  may include operations performed by a host device  505 , which may be an example of the host device described with reference to  FIGS.  1 ,  3 , and  4   . The memory device  510  may be an example of a memory device (e.g., the memory device  110 , the memory dice  160 , the memory die  200 , or the memory device  310 ) as described with reference to  FIGS.  1  through  4   . 
     At  515 , the memory device  510 , comprising a memory array, may receive a command from the host device  505 . In some cases, the command may include an instruction and an address. 
     At  520 , the memory device  510  may identify a set of valid commands for the memory device  510 . In some cases, the set of valid commands may be preconfigured in the memory device  510 . In some other cases, the set of valid commands may be programmable. Here, the memory device  510  may receive, from the host device  505 , a signal indicating the set of valid commands. 
     At  525 , the memory device  510  may determine that the command (e.g., received at  515 ) is absent from the set of valid commands (e.g., the command is invalid). In some cases, the memory device  510  may determine the validity of the command by comparing the command to a set of valid commands. 
     At  530 , the memory device  510  may block, based at least in part on determining that the command is absent from the set of valid commands, the command from being decoded for execution by the memory device. 
     At  535 , the memory device  510  may optionally switch from an access mode of operation (e.g., a first mode of operation) of the memory device  510  to a safe mode of operation (e.g., a second mode of operation) of the memory device  510  based at least in part on determining that the command is absent from the set of valid commands. In some cases, the memory device  510  may restrict access to at least one address of the memory array based at least in part on switching to the safe mode of operation. In some cases, the memory device  510  may operate at least one bank of the memory in a self-refresh mode based at least in part on switching to the safe mode of operation. Additionally or alternatively, the memory device  510  may restrict the execution for at least one command of the set of valid commands based at least in part on switching to the safe mode of operation (e.g., the execution of write commands may be restricted). 
     In the case that memory device switches to operating according to a safe mode at  535 , the memory device may subsequently receive, from the host device  505  while operating in the safe mode, a command sequence for resetting the memory device  510  to the access mode (not shown). The memory device  510  may switch from the safe mode to the access mode based at least in part on receiving the command sequence. 
     At  540 , the memory device  510  may optionally transmit, to the host device  505 , an indication that the command is absent from the set of valid commands (e.g., indicate that the command is invalid). In some cases, the memory device  510  may transmit the indication based at least in part on a quantity of commands determined to be invalid satisfying a threshold. The memory device  510  may determine the threshold based on receiving a signal indicating the threshold from the host device  505 . 
       FIG.  6    illustrates an example of a process flow  600  that supports techniques for command block management. In some examples, process flow  600  may be implemented by aspects of the systems  100  and  300 , memory die  200 , and process flows  400  and  500 . The process flow  600  may include operations performed by a host device  605 , which may be an example of the host device described with reference to  FIGS.  1 ,  3 ,  4 , and  5   . The process flow  600  may include operations performed by a memory device  610 , which may be an example of a memory device (e.g., the memory device  110 , the memory dice  160 , the memory die  200 , the memory device  310 , or the memory device  510 ) as described with reference to  FIGS.  1  through  5   . 
     At  615 , the memory device  610  may receive a plurality of commands (e.g., in contiguous or non-contiguous clock cycles) from a host device  605 . Each of the plurality of commands may include an instruction and/or address (e.g., row address, column address). 
     At  620 , the memory device  610  may determine whether each command of the plurality of commands is included in a set of defined commands. In some cases, the memory device  610  may store the set of defined commands at the memory device  610 . Here, the memory device  610  may determine whether each command is included in the set of defined commands by comparing each of the plurality of commands to the stored set of defined commands. 
     At  625 , the memory device  610  may decode a first command of the plurality of commands for execution on a memory array of the memory device  610  based at least in part on determining that the first command is included in the set of defined commands (e.g., the first command may be defined). 
     At  630 , the memory device  610  may block a second command of the plurality of commands from being decoded for execution on the memory array based at least in part on determining that the second command is absent from the set of defined commands (e.g., the command may be undefined). 
     At  635 , the memory device  610  may, in some cases, determine a quantity of commands of the plurality of commands that are absent from the set of defined commands. That is, the memory device  610  may determine a number of commands that are undefined. In some cases, the memory device  610  may compare the quantity to a threshold. In some examples, the memory device  610  may store one or more commands of the plurality of commands based at least in part on determining that the one or more commands are absent from the set of defined commands. 
     At  640 , the memory device  610  may switch from a first mode of operation (e.g., an access mode) of the memory device  610  to a second mode of operation (e.g., a safe mode) of the memory device  610  based on determining that the quantity satisfies the threshold. That is, the memory device  610  may switch to a safe mode in the event that a number of undefined commands satisfies the threshold. In some cases, the memory device  610  may determine the threshold by receiving, from the host device  605 , a signal indicating the threshold. 
     At  645 , the memory device  610  may transmit, to the host device  605 , an indication that the quantity satisfies the threshold. 
       FIG.  7    illustrates an example of a process flow  700  that supports techniques for command block management. In some examples, process flow  700  may be implemented by aspects of the systems  100  and  300 , memory die  200 , and process flows  400 ,  500 , and  600 . The process flow  700  may include operations performed by a host device  705 , which may be an example of the host device described with reference to  FIGS.  1 ,  3 ,  4 ,  5 , and  6   . The process flow  700  may include operations performed by a memory device  710 , which may be an example of a memory device (e.g., the memory device  110 , the memory dice  160 , the memory die  200 , the memory device  310 , the memory device  510 , or the memory device  610 ) as described with reference to  FIGS.  1  through  6   . 
     At  715 , the host device  705  may transmit, to the memory device  710 , a command for an operation on a memory array of the memory device  710 . The command may include an instruction and/or address (e.g., row address, column address). 
     At  720 , the host device  705  may receive, from the memory device  710  in response to the command, an indication that the command as received at the memory device  710  is absent from a set of valid commands for the memory device  710  (e.g., the command is invalid for the memory device  710 ). In some cases, the indication may further include an indication that the memory device  710  may have switched from a first mode of operation (e.g., an access mode of operation) to a second mode of operation (e.g., a safe mode of operation) based on the command. 
     At  725 , the host device  705  may process a second command from the memory device based on the indication. In some cases, processing a second command may include the host device  705  modifying commands that are waiting to be sent to the memory device  710 . For example, the host device  705  may change commands that are indicated as invalid by the memory device  710 . In another example, the host device  705  may modify commands that may not be executed by the memory device  710  according to the second mode of operation. In another case, processing a second command may include the host device  705  determining to retransmit the first command. 
     At  730 , the host device  705  may transmit, to the memory device  710 , a second command. In some cases, the second command may be part of a command sequence. In a first example, memory device  710  may be operating in a second mode (e.g., a safe mode as indicated at  720 ). Here, the host device  705  may transmit, to the memory device  710  while the memory device  710  is operating in the second mode, a command sequence for resetting the memory device  710  to the first mode. In a second example, the host device  705  may transmit, to the memory device  710 , a command sequence for adding the command to the set valid commands. In a third example, the host device  705  may transmit, to the memory device  710 , a request for a representation of the command as received by the memory device  710 . Here, the host device  705  may receive, from the memory device  710 , an indication of the representation of the command. 
       FIG.  8    shows a block diagram  800  of a device  805  that supports command block management as disclosed herein. The device  805  may be an example of aspects of a memory device such as memory device  110 , memory device  310 , memory device  510 , memory device  610 , or memory device  710  as disclosed herein with reference to  FIGS.  1 ,  3 ,  5 ,  6 , and  7   . The device  805  may include command receiver  810 , a valid command set manager  815 , a command validation manager  820 , a command blocker  825 , an operation mode manager  830 , a feedback component  835 , a threshold manager  840 , and a command execution manager  845 . Each of these modules may communicate, directly or indirectly, with one another (e.g., via one or more buses). 
     The command receiver  810  may receive, at a memory device including a memory array, a command from a host device. In some cases, the command includes an instruction and an address. 
     The valid command set manager  815  may identify a set of valid commands for the memory device. In some examples, the valid command set manager  815  may receive, from the host device, a signal indicating the set of valid commands. In some other examples, the set of valid commands is preconfigured in the memory device. 
     The command validation manager  820  may determine that the command is absent from the set of valid commands based on evaluating the command and the set of valid commands. 
     The command blocker  825  may block, based on determining that the command is absent from the set of valid commands, the command from being decoded for execution by the memory device. 
     The operation mode manager  830  may switch from a first mode of operation of the memory device to a second mode of operation of the memory device based on determining that the command is absent from the set of valid commands. In some examples, the operation mode manager  830  may restrict access to at least one address of the memory array based on switching to the second mode of operation. In some examples, the operation mode manager  830  may operate at least one bank of the memory array in a self-refresh mode based on switching to the second mode of operation. In some other examples, the operation mode manager  830  may restrict execution for at least one command of the set of valid commands based on switching to the second mode of operation. In some examples, the operation mode manager  830  may receive, from the host device while operating in the second mode, a command sequence for resetting the memory device to the first mode. In some examples, the operation mode manager  830  may switch the memory device from the second mode to the first mode based on receiving the command sequence. 
     In some examples, the feedback component  835  may transmit, to the host device, an indication that the command is absent from the set of valid commands. 
     The command receiver  810  may receive, from a host device at a memory device including a memory array, a command for an operation by the memory device. The command validation manager  820  may determine a validity of the command by comparing the command to a set of valid commands. 
     The feedback component  835  may transmit, to the host device, an indication of the validity of the command. In some examples, the feedback component  835  may transmit the indication based on a quantity of commands determined to be invalid satisfying a threshold. In some cases, the threshold manager  840  may receive a signal indicating the threshold from the host device. 
     The command receiver  810  may receive, at a memory device, a set of commands from a host device. 
     The command validation manager  820  may determine whether each command of the set of commands is included in a set of defined commands. In some cases, the command validation manager  820  may store one or more commands of the set of commands based on determining that the one or more commands are absent from the set of defined commands. In some examples, the command validation manager  820  may store the set of defined commands at the memory device. In some examples, the command validation manager  820  may determine a quantity of commands of the set of commands that are absent from the set of defined commands. 
     The threshold manager  840  may receive, from the host device, a signal indicating the threshold. In some examples, the threshold manager  840  may compare the quantity to a threshold. 
     The operation mode manager  830  may switch from a first mode of operation of the memory device to a second mode of operation of the memory device based on determining that the quantity satisfies the threshold. 
     The feedback component  835  may transmit, to the host device, an indication that the quantity satisfies the threshold. In some examples, the feedback component  835  may transmit, to the host device, an indication of the one or more commands (e.g., the one or more commands stored based on determining that the one or more commands are absent from the set of defined commands). 
     The command execution manager  845  may decode a first command of the set of commands for execution on a memory array of the memory device based on determining that the first command is included in the set of defined commands. 
     The command blocker  825  may block a second command of the set of commands from being decoded for execution on the memory array based on determining that the second command is absent from the set of defined commands. 
       FIG.  9    shows a block diagram  900  of a device  905  that supports command block management as disclosed herein. The device  905  may be an example of aspects of a host device such as host device  305 , host device  505 , host device  605 , or host device  705  as disclosed herein with reference to  FIGS.  3  and  5  through  7   . The device  905  may include a command transmitter  910 , a feedback receiver  915 , and a command processor  920 . Each of these modules may communicate, directly or indirectly, with one another (e.g., via one or more buses). 
     The command transmitter  910  may transmit, to a memory device, a command for an operation on a memory array of the memory device. In some examples, the command transmitter  910  may transmit, to the memory device, the second command. In some examples, the command transmitter  910  may transmit, to the memory device while the memory device is operating in the second mode, a command sequence for resetting the memory device to the first mode. In some cases, the command transmitter  910  may transmit, to the memory device, a command sequence that includes the second command, the command sequence for adding the command to the set of valid commands. In some instances, the command transmitter  910  may transmit, to the memory device, a request for a representation of the command as received by the memory device. 
     The feedback receiver  915  may receive, from the memory device in response to the command, an indication that the command as received at the memory device is absent from a set of valid commands for the memory device. In some examples, the feedback receiver  915  may receive, from the memory device, an indication that the memory device has switched from a first mode of operation to a second mode of operation based on the command. In some instances, the feedback receiver  915  may receive, from the memory device, an indication of the representation of the command. 
     The command processor  920  may process a second command for the memory device based on the indication. 
       FIG.  10    shows a flowchart illustrating a method  1000  that supports systems, devices, and methods for command block management as disclosed herein. The operations of method  1000  may be implemented by a memory device (e.g., memory device  110 , memory device  310 , memory device  510 , memory device  610 , or memory device  710  as disclosed herein with reference to  FIGS.  1 ,  3 ,  5 ,  6 , and  7   ) or its components as described herein. In some examples, a memory device may execute a set of instructions to control the functional elements of the memory device to perform the functions described herein. Additionally or alternatively, a memory device may perform aspects of the functions described below using special-purpose hardware. 
     At  1005 , the memory device may receive, at a memory device including a memory array, a command from a host device. The operations of  1005  may be performed according to the methods described herein. In some examples, aspects of the operations of  1005  may be performed by a command receiver as described with reference to  FIG.  8   . 
     At  1010 , the memory device may identify a set of valid commands for the memory device. The operations of  1010  may be performed according to the methods described herein. In some examples, aspects of the operations of  1010  may be performed by a valid command set manager as described with reference to  FIG.  8   . 
     At  1015 , the memory device may determine that the command is absent from the set of valid commands based on evaluating the command and the set of valid commands. The operations of  1015  may be performed according to the methods described herein. In some examples, aspects of the operations of  1015  may be performed by a command validation manager as described with reference to  FIG.  8   . 
     At  1020 , the memory device may block, based on determining that the command is absent from the set of valid commands, the command from being decoded for execution by the memory device. The operations of  1020  may be performed according to the methods described herein. In some examples, aspects of the operations of  1020  may be performed by a command blocker as described with reference to  FIG.  8   . 
     An apparatus for performing a method or methods, such as the method  1000 , is described. The apparatus may include means for means for receiving, at a memory device including a memory array, a command from a host device, identifying a set of valid commands for the memory device, determining that the command is absent from the set of valid commands based on evaluating the command and the set of valid commands, and blocking, based on determining that the command is absent from the set of valid commands, the command from being decoded for execution by the memory device. 
     In some examples, the apparatus may include features for switching from a first mode of operation of the memory device to a second mode of operation of the memory device based on determining that the command may be absent from the set of valid commands. 
     In some cases, the apparatus may include features for restricting access to at least one address of the memory array based on switching to the second mode of operation. 
     In some instances, the apparatus may include features for operating at least one bank of the memory array in a self-refresh mode based on switching to the second mode of operation. 
     In some examples, the apparatus may include features for restricting execution for at least one command of the set of valid commands based on switching to the second mode of operation. 
     In some cases, the apparatus may include features for receiving, from the host device while operating in the second mode, a command sequence for resetting the memory device to the first mode, and switching the memory device from the second mode to the first mode based on receiving the command sequence. 
     In some instances, the apparatus may include features for transmitting, to the host device, an indication that the command may be absent from the set of valid commands. 
     In some examples, the apparatus may include features for receiving, from the host device, a signal indicating the set of valid commands. 
       FIG.  11    shows a flowchart illustrating a method  1100  that supports systems, devices, and methods for command block management as disclosed herein. The operations of method  1100  may be implemented by a memory device (e.g., memory device  110 , memory device  310 , memory device  510 , memory device  610 , or memory device  710  as disclosed herein with reference to  FIGS.  1 ,  3 ,  5 ,  6 , and  7   ) or its components as described herein. In some examples, a memory device may execute a set of instructions to control the functional elements of the memory device to perform the functions described herein. Additionally or alternatively, a memory device may perform aspects of the functions described herein using special-purpose hardware. 
     At  1105 , the memory device including a memory array may receive a command from a host device. The operations of  1105  may be performed according to the methods described herein. In some examples, aspects of the operations of  1105  may be performed by a command receiver as described with reference to  FIG.  8   . 
     At  1110 , the memory device may identify a set of valid commands for the memory device. The operations of  1110  may be performed according to the methods described herein. In some examples, aspects of the operations of  1110  may be performed by a valid command set manager as described with reference to  FIG.  8   . 
     At  1115 , the memory device may determine that the command is absent from the set of valid commands based on evaluating the command and the set of valid commands. The operations of  1115  may be performed according to the methods described herein. In some examples, aspects of the operations of  1115  may be performed by a command validation manager as described with reference to  FIG.  8   . 
     At  1120 , the memory device may block, based on determining that the command is absent from the set of valid commands, the command from being decoded for execution by the memory device. The operations of  1120  may be performed according to the methods described herein. In some examples, aspects of the operations of  1120  may be performed by a command blocker as described with reference to  FIG.  8   . 
     At  1125 , the memory device may switch from a first mode of operation of the memory device to a second mode of operation of the memory device based on determining that the command is absent from the set of valid commands. The operations of  1125  may be performed according to the methods described herein. In some examples, aspects of the operations of  1125  may be performed by an operation mode manager as described with reference to  FIG.  8   . 
     At  1130 , the memory device may transmit, to the host device, an indication that the command is absent from the set of valid commands. The operations of  1130  may be performed according to the methods described herein. In some examples, aspects of the operations of  1130  may be performed by a feedback component as described with reference to  FIG.  8   . 
       FIG.  12    shows a flowchart illustrating a method  1200  that supports systems, devices, and methods for command block management as disclosed herein. The operations of method  1200  may be implemented by a memory device (e.g., memory device  110 , memory device  310 , memory device  510 , memory device  610 , or memory device  710  as disclosed herein with reference to  FIGS.  1 ,  3 ,  5 ,  6 , and  7   ) or its components as described herein. In some examples, a memory device may execute a set of instructions to control the functional elements of the memory device to perform the functions described herein. Additionally or alternatively, a memory device may perform aspects of the functions described herein using special-purpose hardware. 
     At  1205 , the memory device may receive, from a host device at a memory device including a memory array, a command for an operation by the memory device. The operations of  1205  may be performed according to the methods described herein. In some examples, aspects of the operations of  1205  may be performed by a command receiver as described with reference to  FIG.  8   . 
     At  1210 , the memory device may determine a validity of the command by comparing the command to a set of valid commands. The operations of  1210  may be performed according to the methods described herein. In some examples, aspects of the operations of  1210  may be performed by a command validation manager as described with reference to  FIG.  8   . 
     At  1215 , the memory device may transmit, to the host device, an indication of the validity of the command. The operations of  1215  may be performed according to the methods described herein. In some examples, aspects of the operations of  1215  may be performed by a feedback component as described with reference to  FIG.  8   . 
     An apparatus for performing a method or methods, such as the method  1200 , is described. The apparatus may include means for receiving, from a host device at a memory device including a memory array, a command for an operation by the memory device, determining a validity of the command by comparing the command to a set of valid commands, and transmitting, to the host device, an indication of the validity of the command. 
     In some examples, the apparatus may include features for transmitting the indication based on a quantity of commands determined to be invalid satisfying a threshold. 
     In some cases, the apparatus may include features for receiving a signal indicating the threshold from the host device. 
       FIG.  13    shows a flowchart illustrating a method  1300  that supports systems, devices, and methods for command block management as disclosed herein. The operations of method  1300  may be implemented by a memory device (e.g., memory device  110 , memory device  310 , memory device  510 , memory device  610 , or memory device  710  as disclosed herein with reference to  FIGS.  1 ,  3 ,  5 ,  6 , and  7   ) or its components as described herein. In some examples, a memory device may execute a set of instructions to control the functional elements of the memory device to perform the functions described herein. Additionally or alternatively, a memory device may perform aspects of the functions described herein using special-purpose hardware. 
     At  1305 , the memory device may receive, at a memory device, a set of commands from a host device. The operations of  1305  may be performed according to the methods described herein. In some examples, aspects of the operations of  1305  may be performed by a command receiver as described with reference to  FIG.  8   . 
     At  1310 , the memory device may determine whether each command of the set of commands is included in a set of defined commands. The operations of  1310  may be performed according to the methods described herein. In some examples, aspects of the operations of  1310  may be performed by a command validation manager as described with reference to  FIG.  8   . 
     At  1315 , the memory device may decode a first command of the set of commands for execution on a memory array of the memory device based on determining that the first command is included in the set of defined commands. The operations of  1315  may be performed according to the methods described herein. In some examples, aspects of the operations of  1315  may be performed by a command execution manager as described with reference to  FIG.  8   . 
     At  1320 , the memory device may block a second command of the set of commands from being decoded for execution on the memory array based on determining that the second command is absent from the set of defined commands. The operations of  1320  may be performed according to the methods described herein. In some examples, aspects of the operations of  1320  may be performed by a command blocker as described with reference to  FIG.  8   . 
     An apparatus for performing a method or methods, such as the method  1300 , is described. The apparatus may include means for receiving, at a memory device, a set of commands from a host device, determining whether each command of the set of commands is included in a set of defined commands, decoding a first command of the set of commands for execution on a memory array of the memory device based on determining that the first command is included in the set of defined commands, and blocking a second command of the set of commands from being decoded for execution on the memory array based on determining that the second command is absent from the set of defined commands. 
     In some examples, the apparatus may include features for determining a quantity of commands of the set of commands that may be absent from the set of defined commands, and comparing the quantity to a threshold. 
     In some cases, the apparatus may include features for switching from a first mode of operation of the memory device to a second mode of operation of the memory device based on determining that the quantity satisfies the threshold. 
     In some instances, the apparatus may include features for transmitting, to the host device, an indication that the quantity satisfies the threshold. 
     In some examples, the apparatus may include features for storing one or more commands of the set of commands based on determining that the one or more commands may be absent from the set of defined commands, and transmitting, to the host device, an indication of the one or more commands. 
     In some aspects, the apparatus may include features for receiving, from the host device, a signal indicating the threshold. 
     In some cases, the apparatus may include features for storing the set of defined commands at the memory device. 
       FIG.  14    shows a flowchart illustrating a method  1400  that supports command block management as disclosed herein. The operations of method  1400  may be implemented may be implemented by a host device (e.g., host device  305 , host device  505 , host device  605 , or host device  705  as disclosed herein with reference to  FIGS.  3  and  5  through  7   ) or its components as described herein. In some examples, a host device may execute a set of instructions to control the functional elements of the host device to perform the functions described herein. Additionally or alternatively, a host device may perform aspects of the functions described herein using special-purpose hardware. 
     At  1405 , the host device may transmit, to a memory device, a command for an operation on a memory array of the memory device. The operations of  1405  may be performed according to the methods described herein. In some examples, aspects of the operations of  1405  may be performed by a command transmitter as described with reference to  FIG.  9   . 
     At  1410 , the host device may receive, from the memory device in response to the command, an indication that the command as received at the memory device is absent from a set of valid commands for the memory device. The operations of  1410  may be performed according to the methods described herein. In some examples, aspects of the operations of  1410  may be performed by a feedback receiver as described with reference to  FIG.  9   . 
     At  1415 , the host device may process a second command for the memory device based on the indication. The operations of  1415  may be performed according to the methods described herein. In some examples, aspects of the operations of  1415  may be performed by a command processor as described with reference to  FIG.  9   . 
     At  1420 , the host device may transmit, to the memory device, the second command. The operations of  1420  may be performed according to the methods described herein. In some examples, aspects of the operations of  1420  may be performed by a command transmitter as described with reference to  FIG.  9   . 
     An apparatus for performing a method or methods, such as the method  1400 , is described. The apparatus may include means for transmitting, to a memory device, a command for an operation on a memory array of the memory device, receiving, from the memory device in response to the command, an indication that the command as received at the memory device is absent from a set of valid commands for the memory device, processing a second command for the memory device based on the indication, and transmitting, to the memory device, the second command. 
     In some examples, the apparatus may include features for receiving, from the memory device, an indication that the memory device may have switched from a first mode of operation to a second mode of operation based on the command. 
     In some cases, the apparatus may include features for transmitting, to the memory device while the memory device may be operating in the second mode, a command sequence for resetting the memory device to the first mode. 
     In some instances, the apparatus may include features for transmitting, to the memory device, a command sequence that includes the second command, the command sequence for adding the command to the set of valid commands. 
     In some examples, the apparatus may include features for transmitting, to the memory device, a request for a representation of the command as received by the memory device, and receiving, from the memory device, an indication of the representation of the command. 
     It should be noted that the methods described above describe possible implementations, and that the operations and the steps may be rearranged or otherwise modified and that other implementations are possible. Further, aspects from two or more of the methods may be combined. 
     In some examples, an apparatus for command block management may perform aspects of the functions described herein using general- or special-purpose hardware. The apparatus may include a memory array of a memory device, circuitry operable to receive a set of commands from a host device, a decoder coupled with the circuitry and the memory array and operable to decode commands received from the circuitry for execution by the apparatus; and where the circuitry is operable to propagate a first command of the plurality of commands to the decoder based on determining that the first command is included in a set of valid commands, and block a second command from being sent to the decoder based on a determination that the second command is absent from the set of valid commands. 
     In some cases, the circuitry may be further operable to switch from a first mode of operation of the memory device to a second mode of operation of the memory device based on determining that the second command is absent from the set of valid commands. 
     In some instances, the circuitry may be further operable to switch from the first mode of operation to the second mode of operation based on a quantity of received commands that may be not included in the set of valid commands satisfying a threshold. 
     In some examples, the circuitry may be further operable to receive, from the host device while operating in the second mode, a command sequence for resetting the memory device to the first mode, and switch the memory device from the second mode to the first mode based on receiving the command sequence. 
     In some cases, the circuitry may be further operable to transmit, to the host device, an indication that the second command may be not included in the set of valid commands. 
     In some instances, the circuitry may be further operable to transmit the indication based on a quantity of received commands that may be not included in the set of valid commands satisfying a threshold. 
     In some examples, the apparatus may include a buffer operable to store one or more commands of the set of commands based on determining that the second command may be absent from the set of valid commands. 
     In some cases, the circuitry may be further operable to receive, from the host device, a signal indicating a request for a stored command of the set of commands, and transmit, to the host device, an indication of the stored command. 
     In some instances, each of the set of commands may be received via a set of instruction pins, and where the set of valid commands includes a subset of a command space of combinations of the set of instruction pins. 
     In some examples, each of the set of commands may be received via a set of instruction pins and a set of address pins, and where the set of valid commands includes a subset of a command space of combinations of the set of instruction pins and the set of address pins. 
     Although certain features may be described herein with respect to or in the context of DRAM technology, this is for illustrative purposes only, and one of ordinary skill in the art will appreciate that the teachings herein may be applied to any type of memory device. For example, the teachings herein may be applied to volatile or non-volatile memory devices such as magnetic hard disks, random access memory (RAM), read-only memory (ROM), dynamic RAM (DRAM), synchronous dynamic RAM (SDRAM), ferroelectric RAM (FeRAM), magnetic RAM (MRAM), resistive RAM (RRAM), flash memory, phase change memory (PCM), and others. 
     Information and signals described herein may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof. Some drawings may illustrate signals as a single signal; however, it will be understood by a person of ordinary skill in the art that the signal may represent a bus of signals, where the bus may have a variety of bit widths. 
     As used herein, the term “virtual ground” refers to a node of an electrical circuit that is held at a voltage of approximately zero volts (0V) but that is not directly coupled with ground. Accordingly, the voltage of a virtual ground may temporarily fluctuate and return to approximately 0V at steady state. A virtual ground may be implemented using various electronic circuit elements, such as a voltage divider consisting of operational amplifiers and resistors. Other implementations are also possible. “Virtual grounding” or “virtually grounded” means connected to approximately 0V. 
     The terms “electronic communication,” “conductive contact,” “connected,” and “coupled” may refer to a relationship between components that supports the flow of signals between the components. Components are considered in electronic communication with (or in conductive contact with or connected with or coupled with) one another if there is any conductive path between the components that can, at any time, support the flow of signals between the components. At any given time, the conductive path between components that are in electronic communication with each other (or in conductive contact with or connected with or coupled with) may be an open circuit or a closed circuit based on the operation of the device that includes the connected components. The conductive path between connected components may be a direct conductive path between the components or the conductive path between connected components may be an indirect conductive path that may include intermediate components, such as switches, transistors, or other components. In some cases, the flow of signals between the connected components may be interrupted for a time, for example, using one or more intermediate components such as switches or transistors. 
     The term “coupling” refers to condition of moving from an open-circuit relationship between components in which signals are not presently capable of being communicated between the components over a conductive path to a closed-circuit relationship between components in which signals are capable of being communicated between components over the conductive path. When a component, such as a controller, couples other components together, the component initiates a change that allows signals to flow between the other components over a conductive path that previously did not permit signals to flow. 
     The term “isolated” refers to a relationship between components in which signals are not presently capable of flowing between the components. Components are isolated from each other if there is an open circuit between them. For example, two components separated by a switch that is positioned between the components are isolated from each other when the switch is open. When a controller isolates two components, the controller affects a change that prevents signals from flowing between the components using a conductive path that previously permitted signals to flow. 
     The devices discussed herein, including a memory array, may be formed on a semiconductor substrate, such as silicon, germanium, silicon-germanium alloy, gallium arsenide, gallium nitride, etc. In some cases, the substrate is a semiconductor wafer. In other cases, the substrate may be a silicon-on-insulator (SOI) substrate, such as silicon-on-glass (SOG) or silicon-on-sapphire (SOP), or epitaxial layers of semiconductor materials on another substrate. The conductivity of the substrate, or sub-regions of the substrate, may be controlled through doping using various chemical species including, but not limited to, phosphorous, boron, or arsenic. Doping may be performed during the initial formation or growth of the substrate, by ion-implantation, or by any other doping means. 
     A switching component or a transistor discussed herein may represent a field-effect transistor (FET) and comprise a three terminal device including a source, drain, and gate. The terminals may be connected to other electronic elements through conductive materials, e.g., metals. The source and drain may be conductive and may comprise a heavily-doped, e.g., degenerate, semiconductor region. The source and drain may be separated by a lightly-doped semiconductor region or channel. If the channel is n-type (i.e., majority carriers are signals), then the FET may be referred to as a n-type FET. If the channel is p-type (i.e., majority carriers are holes), then the FET may be referred to as a p-type FET. The channel may be capped by an insulating gate oxide. The channel conductivity may be controlled by applying a voltage to the gate. For example, applying a positive voltage or negative voltage to an n-type FET or a p-type FET, respectively, may result in the channel becoming conductive. A transistor may be “on” or “activated” when a voltage greater than or equal to the transistor&#39;s threshold voltage is applied to the transistor gate. The transistor may be “off” or “deactivated” when a voltage less than the transistor&#39;s threshold voltage is applied to the transistor gate. 
     The description set forth herein, in connection with the appended drawings, describes example configurations and does not represent all the examples that may be implemented or that are within the scope of the claims. The term “exemplary” used herein means “serving as an example, instance, or illustration,” and not “preferred” or “advantageous over other examples.” The detailed description includes specific details to providing an understanding of the described techniques. These techniques, however, may be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form to avoid obscuring the concepts of the described examples. 
     In the appended figures, similar components or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If just the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label. 
     Information and signals described herein may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof. 
     The various illustrative blocks and modules described in connection with the disclosure herein may be implemented or performed with a general-purpose processor, a DSP, an ASIC, an FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration). 
     The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Other examples and implementations are within the scope of the disclosure and appended claims. For example, due to the nature of software, functions described above can be implemented using software executed by a processor, hardware, firmware, hardwiring, or combinations of any of these. Features implementing functions may also be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations. Also, as used herein, including in the claims, “or” as used in a list of items (for example, a list of items prefaced by a phrase such as “at least one of” or “one or more of”) indicates an inclusive list such that, for example, a list of at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). Also, as used herein, the phrase “based on” shall not be construed as a reference to a closed set of conditions. For example, an exemplary step that is described as “based on condition A” may be based on both a condition A and a condition B without departing from the scope of the present disclosure. In other words, as used herein, the phrase “based on” shall be construed in the same manner as the phrase “based at least in part on.” 
     The description herein is provided to enable a person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the scope of the disclosure. Thus, the disclosure is not limited to the examples and designs described herein, but is to be accorded the broadest scope consistent with the principles and novel features disclosed herein.