Read and Write operations in Memory

24 Jan, 2022
A memory unit stores binary information in groups of bits called words. Data input lines provide the information to be stored into the memory, Data output lines carry the information out from the memory. The control lines Read and write specifies the direction of transfer of data. Basically, in the memory organization, there are  memory locations indexing from 0 to  where l is the address buses. We can describe the memory in terms of the bytes using the following formula:
Where,l is the total address busesN is the memory in bytes
For example, some storage can be described below in terms of bytes using the above formula:
 1kB= 210 Bytes
 64 kB = 26 x 210 Bytes
       = 216 Bytes
 4 GB = 22 x 210(kB) x 210(MB) x 210 (GB)
      = 232 Bytes

Memory Address Register (MAR) is the address register which is used to store the address of the memory location where the operation is being performed.Memory Data Register (MDR) is the data register which is used to store the data on which the operation is being performed.
Memory Read Operation:Memory read operation transfers the desired word to address lines and activates the read control line.Description of memory read operation is given below:In the above diagram initially, MDR can contain any garbage value and MAR is containing 2003 memory address. After the execution of read instruction, the data of memory location 2003 will be read and the MDR will get updated by the value of the 2003 memory location (3D).Memory Write Operation:Memory write operation transfers the address of the desired word to the address lines, transfers the data bits to be stored in memory to the data input lines. Then it activates the write control line. Description of the write operation is given below:In the above diagram, the MAR contains 2003 and MDR contains 3D. After the execution of write instruction 3D will be written at 2003 memory location.
Memory Read Operation:Memory read operation transfers the desired word to address lines and activates the read control line.Description of memory read operation is given below:In the above diagram initially, MDR can contain any garbage value and MAR is containing 2003 memory address. After the execution of read instruction, the data of memory location 2003 will be read and the MDR will get updated by the value of the 2003 memory location (3D).
In the above diagram initially, MDR can contain any garbage value and MAR is containing 2003 memory address. After the execution of read instruction, the data of memory location 2003 will be read and the MDR will get updated by the value of the 2003 memory location (3D).
Memory Write Operation:Memory write operation transfers the address of the desired word to the address lines, transfers the data bits to be stored in memory to the data input lines. Then it activates the write control line. Description of the write operation is given below:In the above diagram, the MAR contains 2003 and MDR contains 3D. After the execution of write instruction 3D will be written at 2003 memory location.
In the above diagram, the MAR contains 2003 and MDR contains 3D. After the execution of write instruction 3D will be written at 2003 memory location.
VaibhavRai3
tanwarsinghvaibhav
Computer Organization & Architecture
GATE CS
Writing code in comment?
Please use ide.geeksforgeeks.org,
generate link and share the link here.
Program for Decimal to Binary Conversion
Logical and Physical Address in Operating System
Direct Access Media (DMA) Controller in Computer Architecture
Interrupts
Architecture of 8085 microprocessor
Layers of OSI Model
ACID Properties in DBMS
TCP/IP Model
Types of Operating Systems
Normal Forms in DBMS