Abstract:
An extended Secure-Digital (SD) card has a second interface that uses some of the SD-interface lines. The SD card&#39;s mechanical and electrical card-interface is used, but 2 or 4 signals in the SD interface are multiplexed for use by the second interface. The second interface can have a single differential pair of serial-data lines to perform Universal-Serial-Bus (USB) transfers, or two pairs of differential data lines for Serial-Advanced-Technology-Attachment (SATA), Peripheral Component Interconnect Express (PCIE), or IEEE 1394 transfers. A card-detection routine on a host can initially use the SD interface to detect extended capabilities and command the card to switch to using the second interface. The extended SD card can communicate with legacy SD hosts using just the SD interface, and extended SD hosts can read legacy SD cards using just the SD interface, or extended SD cards using the second interface. MultiMediaCard and Memory Stick are alternatives.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application is a continuation-in-part of the co-pending application for “Dual-Personality Extended-USB Plug and Receptacle with PCI-Express or Serial-AT-Attachment Extensions”, U.S. Ser. No. 10/708,172, filed Feb. 12, 2004. 

   BACKGROUND OF INVENTION 
   This invention relates to removable-card interfaces, and more particularly to dual-protocol interfaces for removable cards. 
   Flash-memory cards are widely used for storing digital pictures captured by digital cameras. One useful format is the Secure-Digital (SD) format, which is an extension of the earlier MultiMediaCard (MMC) format. SD cards are thin and the area of a large postage stamp. Sony&#39;s Memory Stick (MS) is another digital-file-card format that is shaped somewhat like a stick of chewing gum. 
   SD cards are also useful as add-on memory cards for other devices, such as portable music players, personal digital assistants (PDAs), and even notebook computers. SD cards are hot-swappable, allowing the user to easily insert and remove SD cards without rebooting or cycling power. Since the SD cards are small, durable, and removable, data files can easily be transported among electronic devices by being copied to an SD card. SD cards are not limited to flash-memory cards, but other applications such as communications transceivers can be implemented as SD cards. 
   The SD interface currently supports a top transfer rate of 100 Mb/s, which is sufficient for many applications. However, some applications such as storage and transport of full-motion video could benefit from higher transfer rates. 
   Other bus interfaces offer higher transfer rates. Universal-Serial-Bus (USB) has a top transfer rate of 480 Mb/s. Peripheral-Component-lnterconnect (PCI) Express, at 2.5 Gb/s, and Serial-Advanced-Technology-Attachment (SATA), at 1.5 Gb/s and 3.0 Gb/s, are two examples of high-speed serial bus interfaces for next generation devices. IEEE 1394 (Firewire) supports 3.2 Gb/s. Serial Attached Small-Computer System Interface (SCSI) supports 1.5 Gb/s or 3.0 Gb/s. These are 5 to 32 times faster than the SD interface. 
   A new removable-card form-factor known as ExpressCard has been developed by the Personal-Computer Memory Card International Association (PCMCIA), PCI, and USB standards groups. ExpressCard 26 is about 75 mm long, 34 mm wide, and 5 mm thick and has ExpressCard connector  28 . ExpressCard provides both USB and PCI Express interfaces on the same 26-pin card connector. 
   Serial-ATA is used mostly as an internal expansion interface on PC&#39;s, since it requires two separate connectors. A first 7-pin connector carries signals while a second 15-pin connector is for power. ExpressCard&#39;s large 26-pin connector limits its usefulness and increases the physical size of devices using ExpressCard connectors. Compact-Flash cards also tend to be larger in size than SD cards since Compact-Flash has more connector pins. 
   SD and MMC are complementary card interfaces, and are sometimes lumped together and referred to as SD/MMC cards. The older MMC cards have 7 metal connector pads while SD has 9 connector pads. MMC cards can fit in SD slots, and SD cards can fit in MMC slots. However, the host must determine which type of card is inserted into its slot. When a MMC card is inserted, only 7 pads are used, while the additional 2 pads are used when a SD card is detected in the slot. 
     FIG. 1  shows a prior-art card-detection routine executed by a host. The host, such as a host personal computer (PC) detects when a card is inserted into a slot, step  200 , such as by detecting the card-detect (CD) pin that is pulled high by a resistor on the SD card. The host sends a sequence of commands to the inserted card that includes a CMD 55  command, step  202 . If the card does not respond properly to the CMD 55  command, step  204 , then the card is an MMC card, not a SD card. A sequence of commands is sent to the MMC card, step  206 , which includes the CMD 1  command. The MMC card is then initialized by a sequence of commands, such as the host reading configuration registers on the MMC card, step  208 . The host uses the 7 pins shared with MMC to communicate with the MMC card. 
   When the inserted card responds to the CMD  55  command, step  204 , then the card may be a SD card. Further commands are sent to the card including the advanced command ACMD 41 , step  210 . If the card does not respond properly to the ACMD 41 , step  212 , then the card fails, step  214 . 
   When the card responds properly to the ACMD 41 , step  210 , then the card is an SD card. The SD card is then initialized by a sequence of commands, such as the host reading configuration registers on the SD card, step  216 . The host uses the 9-pin SD interface to communicate with the SD card. The host can use one data line or up to four data lines in the SD interface for communication. Data stored on the SD card can be encrypted using higher-level security protocols. 
     FIG. 2  is a flowchart of a prior-art detection-response routine executed by a SD card. The SD card obtains power from the metal contact pads when inserted into the host slot and powers up, step  220 . A card-initialization routine is started, step  222 , which may include various internal self-checks. A controller inside the SD card executes these routines, activates the external interface, and then waits for commands from the host. When a CMD 55  is received from the host, step  224 , then the SD controller waits for an ACMD 41  from the host, step  226 . The card responds to the ACMD 41  from the host, step  228 . The SD card is then ready to receive further commands from the host, step  230 . The full 9-pin SD interface is used. 
   While either MMC or SD cards can be detected, the transfer rate using either MMC or SD cards is slower than many current bus standards. Applications such as video transfers could benefit from a higher-speed interface to a SD card. The thin, small size of the SD card is beneficial, but the slow transfer rates could limit SD-card use in the future. A higher-speed interface to the SD card is desired, as is a detection scheme for use when higher-speed interfaces are available. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
       FIG. 1  shows a prior-art card-detection routine executed by a host. 
       FIG. 2  is a flowchart of a prior-art detection-response routine executed by a SD card. 
       FIG. 3  shows a SD host accepting a MMC card, a SD card, or a Very-high-speed-Secure-Digital (VSD) card. 
       FIG. 4  shows an extended VSD host accepting a MMC card, a SD card, or a VSD card. 
       FIG. 5  is a flowchart of an extended VSD card-detection routine executed by a VSD host. 
       FIG. 6  is a flowchart of a VSD detection-response routine executed by a VSD card. 
       FIG. 7  is a block diagram of a host with an SD connector slot that supports extended-mode communication. 
       FIG. 8  is a block diagram of a VSD card device with an SD connector that supports VSD extended-mode communication. 
       FIG. 9  is a functional diagram of a signal multiplexer. 
       FIG. 10  is a table showing signal multiplexing with a 9-pin SD connector. 
       FIG. 11  is a table showing signal multiplexing with a 7-pin MMC connector. 
       FIG. 12  is a table showing pin multiplexing for an extended 13-pin connector. 
       FIG. 13  is a table showing pin multiplexing for a 10-pin Memory Stick system. 
   

   DETAILED DESCRIPTION 
   The present invention relates to an improvement in insertable cards. The following description is presented to enable one of ordinary skill in the art to make and use the invention as provided in the context of a particular application and its requirements. Various modifications to the preferred embodiment will be apparent to those with skill in the art, and the general principles defined herein may be applied to other embodiments. Therefore, the present invention is not intended to be limited to the particular embodiments shown and described, but is to be accorded the widest scope consistent with the principles and novel features herein disclosed. 
   The inventors have discovered that the existing physical and electrical specifications for the SD card can be used while still supporting higher-speed transfers. The signals from the 9-pin SD-card interface can be multiplexed to controllers for other interfaces that support higher-speed transfers, such as USB, IEEE 1394, SATA, PCI-Express, etc. Thus data transfers can occur using higher-bandwidth protocols using the existing physical SD interface pins. 
   The invention can include a multi-personality host and card system. The application combinations include: a multi-personality host and a multi-personality device, a multi-personality host and a single-personality device, a single-personality host and a multi-personality device, and a single-personality host and a single-personality device. 
   An SD card modified to use a higher-speed serial bus is a very-high-speed SD card, or a VSD card, while a host that can communicate with a VSD card is a VSD host. A VSD card can act as a SD card when inserted into a legacy SD host, while a VSD host can read inserted SD cards. Thus the VSD card and host are backward-compatible. 
     FIG. 3  shows a SD host accepting a MMC card, a SD card, or a VSD card. Host  38  is a legacy SD host that can detect and accept SD card  30  or MMC card  32 . When VSD card  34  is inserted, the SD host controller on host  38  detects a SD card and configures VSD card  34  to operate as a SD card over the normal 9-pin SD interface and SD bus  36 . 
   MMC card  32  has only 7 metal pads and uses 2 fewer of the lines on SD bus  36  than does SD card  30 . SD card  30  has two extra metal pads that are not present on MMC card  32 . One extra metal pad is added near the beveled corner of SD card  30 , while another extra pad is added on the other side of the 7 metal pads. VSD card  34  has the same arrangement of the 9 metal pads as SD card  30 , and can communicate over SD bus  36  with host  38  using the standard SD interface and protocol. 
     FIG. 4  shows an extended VSD host accepting a MMC card, a SD card, or a VSD card. Extended host  42  is a VSD host that can detect and accept SD card  30  or MMC card  32  or VSD card  34 . When MMC card  32  is inserted, extended host  42  uses 7 pins of VSD bus  40  to communicate using the MMC pins and protocol. When SD card  30  is inserted, extended host  42  uses 9 pins of VSD bus  40  to communicate using the SD pins and protocol. 
   When VSD card  34  is inserted, the host controller on extended host  42  detects a VSD card and configures VSD card  34  to operate in extended mode using a high-speed serial-bus standard such as USB over VSD bus  40 . Higher-bandwidth data transfers can then occur over VSD bus  40  using one of the serial-bus standards, such as USB, IEEE 1394, SATA, or PCI-Express. 
   VSD card  34  has the same arrangement of the 9 metal pads as SD card  30 , but contains an internal controller that can couple an internal serial-bus controller to the metal pads rather than the normal SD controller. For example, a USB controller inside VSD card  34  can be coupled to some of the metal pads when VSD card  34  is operating in extended VSD mode. 
     FIG. 5  is a flowchart of an extended VSD card-detection routine executed by a VSD host. The host, such as a host personal computer (PC) detects when a card is inserted into a slot, step  240 , such as by detecting the card-detect (CD) pin that is pulled high by a resistor on the SD or VSD card. The VSD host sends a sequence of commands to the inserted card that includes a CMD 55  command, step  242 . If the card does not respond properly to the CMD 55  command, step  244 , then the card could be an MMC card, or a single-mode card, but not a SD or a VSD card. A sequence of commands is then sent to the card, step  246 , including the CMD 1  command. If card responds properly to the CMD 1  command, then the card is an MMC card. The MMC card is then initialized by a sequence of commands, such as the host reading configuration registers on the MMC card, step  248 . The host uses the 7 pins shared with MMC to communicate with the MMC card. If card dose not respond properly, the host may try to communicate with the card by switching to a different mode. 
   When the inserted card responds to the CMD  55  command, step  244 , then the card may be a VSD card or a SD card. Further commands are sent to the card including the advanced VSD command ACMD 1 , step  250 . If the card does not respond properly to the ACMD 1 , step  252 , then the card cannot be a VSD card. The command sequence starts over again, re-sending the CMD 55  command and later the ACMD 41  command, step  254 . ACMD 1  is a specially-defined advanced command that only a VSD card responds to in the expected manner. For example, a VSD card could respond with a unique code used only for VSD. 
   When the card responds properly to the ACMD 55  and ACMD 41  commands, step  256 , then the card is an SD card. The SD card is then initialized by a sequence of commands, such as the host reading configuration registers on the SD card, step  258 . The host uses the 9-pin SD interface to communicate with the SD card. The host can use one data line or up to four data lines in the SD interface for communication. Data stored on the SD card can be encrypted using higher-level security protocols. 
   When the card does not respond properly to the ACMD 55  and ACMD 41  commands, step  256 , then the card is another type of card. Further identification of the card type may be performed, step  260 , or the card-detection routine can fail. 
   When the card responds properly to the ACMD 1 , step  252 , then the card is a VSD card, step  262 . The extended host can analyze responses from the card from this and other commands, step  264 , to establish the personality and capabilities of the VSD card, step  266 . 
   The VSD card is then initialized by a sequence of commands, such as the host reading configuration registers on the SD card, step  268 . One of the extended serial-bus protocol processors is activated and connected to some of the 9 metal pads of the VSD bus to allow for extended-mode data transfers. 
     FIG. 6  is a flowchart of a VSD detection-response routine executed by a VSD card. The VSD card obtains power from the metal contact pads when inserted into the host slot and powers up, step  280 . A card-initialization routine is started, step  282 , which may include various internal self-checks. A controller inside the VSD card executes these routines, activates the external interface, and then waits for commands from the host. If it is a single-mode card, then the card waits for the host to switch to the same mode to communicate. If it is not a single-mode card, then it waits for the CMD 55  command from host. 
   When a CMD 55  is received from the host, step  284 , then the VSD controller waits for the ACMD 1  from the host, step  286 . The VSD card responds to the ACMD 1  from the VSD host by listing the available extended-serial-bus protocols that the card supports, step  288 . The host chooses one of the available protocols that the host also supports. The card changes its bus transceivers to connect one of the extended serial-bus protocol processors to some of the 9 SD pins, step  290 . For example, USB may be supported. 
   The host sends a command to the VSD card indicating which protocol to use, step  292 . The VSD card then initializes the selected protocol processor and couples it to the appropriate pins on the VSD bus. The VSD card is then ready to receive further commands from the host, step  294 . 
   System Block Diagrams— FIGS. 7–8   
     FIG. 7  is a block diagram of a host with an SD connector slot that supports extended-mode communication. SD card  30 , MMC card  32 , or VSD card  34  could be plugged into VSD connector slot  50  of host  51 . Each card can operate in its own standard mode. 
   Host  51  has processor system  68  for executing programs including card-management and bus-scheduling programs. Multi-personality bus interface  53  processes data from processor system  68  using various protocols. SD processor  56  processes data using the SD protocol, and inputs and outputs data on the SD data lines in VSD connector slot  50 . Other protocols communicate with VSD connector slot  50  through multi-personality bus switch  52 , which selects one protocol processor. 
   The contact pins in VSD connector slot  50  connect to multi-personality bus switch  52  as well as to SD processor  56 . Transceivers in multi-personality bus switch  52  buffer data to and from the transmit and receive pairs of differential data lines in the metal contacts for extended protocols such as PCI-Express, Firewire IEEE 1394, Serial-Attached SCSI, and SATA, and for the older MultiMediaCard. 
   When an initialization routine executed by processor system  68  determines that inserted card is a MMC card, MMC processor  58  is activated to communicate with MMC card  32  inserted into VSD connector slot  50 , while SD processor  56  is disabled. Personality selector  54  configures multi-personality bus switch  52  to connect VSD connector slot  50  to MMC processor  58  when processor system  68  determines that the inserted card is MMC. When the inserted card is SD card  30 , SD processor  56  continues to communicate with the card after initialization is complete. 
   When the initialization routine executed by processor system  68  determines that inserted card is VSD card  34 , SD processor  56  continues to communicate with VSD card  34  until the capabilities of VSD card  34  are determined. Then one of the higher-speed serial-bus protocols is selected for use. For example, when processor system  68  determines that VSD card  34  supports PCI-Express, personality selector  54  configures multi-personality bus switch  52  to connect VSD connector slot  50  to PCI-Express processor  62 . Then processor system  68  communicates with PCI-Express processor  62  instead of SD processor  56  when PCIE extended mode is activated. 
   When the initialization routine executed by processor system  68  determines that the inserted card is VSD card  34 , and supports USB, personality selector  54  configures multi-personality bus switch  52  to connect VSD connector slot  50  to USB processor  60 . Then processor system  68  communicates with USB processor  60  instead of SD processor  56  when USB extended mode is activated. 
   When the initialization routine executed by processor system  68  determines that the inserted card is VSD card  34  that supports SATA, personality selector  54  configures multi-personality bus switch  52  to connect VSD connector slot  50  to SATA processor  64 . Then processor system  68  communicates with SATA processor  64  instead of SD processor  56  when SATA extended mode is activated. 
   When the initialization routine executed by processor system  68  determines that the inserted card is VSD card  34  that supports Firewire, personality selector  54  configures multi-personality bus switch  52  to connect VSD connector slot  50  to IEEE 1394 processor  66 . Then processor system  68  communicates with IEEE 1394 processor  66  instead of SD processor  56  when IEEE 1394 extended mode is activated. 
   VSD card  34  may support more than one extended protocol. Then processor system  68  can select from among the supported protocols. For example, the faster protocol may be selected. VSD host  51  may not support all protocols shown in  FIG. 7 , but may only support a subset. 
     FIG. 8  is a block diagram of a VSD card device with an SD connector that supports VSD extended-mode communication. VSD card device  71  could be VSD card  34  of  FIG. 7 , or VSD card  34  could have only a subset of all the protocol processors that VSD card device  71  has. Likewise, VSD host  51 ′ could be the same as VSD host  51  of  FIG. 7 , or could have only a subset of all the protocol processors that VSD host  51  of  FIG. 7  has. 
   VSD connector  70  of VSD card device  71  could be plugged into SD connector slot  50  of VSD host  51 ′. VSD connector  70  of VSD card device  71  could also be plugged into SD connector slot  50 ′ of SD host  75 , which does not support VSD mode, or VSD connector  70  of VSD card device  71  could be plugged into SD connector slot  50 ″ of MMC host  77 , which does not support VSD mode, but does support MMC or SPI mode. 
   Card device  71  has processor system  88  for executing programs including card-initialization and bus-response programs. Multi-personality bus interface  73  processes data from processor system  88  using various protocols. SD processor  76  processes data using the SD protocol, and inputs and outputs data on the SD data lines in VSD connector  70 . Other protocol processors communicate with VSD connector  70  through multi-personality bus switch  72 , which selects one protocol processor. 
   The contact pins in VSD connector  70  connect to multi-personality bus switch  72  as well as to SD processor  76 . Transceivers in multi-personality bus switch  72  buffer data to and from the transmit and receive pairs of differential data lines in the metal contacts for extended protocols such as PCI-Express, Firewire IEEE 1394, Serial-Attached SCSI, and SATA, and for the older MultiMediaCard. 
   When an initialization routine executed by processor system  88  is commanded to use MMC-compatible SPI mode, when the host is MMC host  77 , MMC processor  78  is activated to communicate with MMC host  77  connected to VSD connector  70 , while SD processor  76  is disabled. Personality selector  74  configures multi-personality bus switch  72  to connect VSD connector  70  to MMC processor  78  when processor system  88  is commanded to use MMC-compatible mode. When the host is SD host  51 , SD processor  76  continues to communicate with SD host  75  after initialization is complete. 
   When the host initialization routine determines that both VSD card device  71  and VSD host  51 ′ can support VSD mode, VSD host  51 ′ sends a command through SD processor  76  to processor system  88  to switch to VSD mode. Then one of the higher-speed serial-bus protocols is selected for use. For example, when processor system  88  is commanded to use PCI-Express, personality selector  74  configures multi-personality bus switch  72  to connect VSD connector  70  to PCI-Express processor  82 . Then processor system  88  communicates with PCI-Express processor  82  instead of SD processor  76  when PCIE extended mode is activated. 
   When the host initialization routine determines that the inserted card supports VSD with USB, processor system  88  is commanded to switch to USB mode. Personality selector  74  configures multi-personality bus switch  72  to connect VSD connector  70  to USB processor  80 . Then processor system  88  communicates with USB processor  80  instead of SD processor  76  when USB extended mode is activated. 
   When the host initialization routine determines that the inserted card supports VSD with SATA, processor system  88  is commanded to switch to SATA mode. Personality selector  74  configures multi-personality bus switch  72  to connect VSD connector  70  to SATA processor  84 . Then processor system  88  communicates with SATA processor  84  instead of SD processor  76  when SATA extended mode is activated. 
   When the host initialization routine determines that the inserted card supports VSD with Firewire, processor system  88  is commanded to switch to Firewire mode. Personality selector  74  configures multi-personality bus switch  72  to connect VSD connector  70  to IEEE 1394 processor  86 . Then processor system  88  communicates with IEEE 1394 processor  86  instead of SD processor  76  when IEEE 1394 extended mode is activated. 
   VSD card device  71  may not support all protocols shown in  FIG. 8 , but may only support a subset. Some of protocol processors may be absent in some embodiments. 
     FIG. 9  is a functional diagram of a signal multiplexer. Multiplexed line  22  could be connected to one of the metal contact pads in the SD connector, or could be an internal bus line. Input buffer  14  buffers line  22  to generate AIN for the A interface, while input buffer  20  buffers line  22  to generate BIN for the B interface. When line  22  is an output or is an I/O line that is being driven, output-enable signal OE is activated high. When the A interface is active, ENA is high and AND gate  10  drives a high to enable output buffer  12 , which drives AOUT onto line  22 . When the B interface is active, ENB is high and AND gate  16  drives a high to enable output buffer  18 , which drives BOUT onto line  22 . 
   Additional interfaces C, D, etc. can mux to the same line  22  by adding additional AND gates and input and output buffers. Additional enable signals ENC, END, etc. can be generated. The interfaces can be for MMC, USB, SATA, IEEE 1394, PCIE, and SD. 
   Interface Pin Tables 
     FIG. 10  is a table showing signal multiplexing with a 9-pin SD connector. Power (VDD) is provided on pin  4 , while grounds are provided on pins  3  and  6 . A clock is input to the card on line  5 , while pin  7  is a serial data I/O DAT 0  for all interfaces. 
   Pin  2  is a bi-directional command CMD line for MMC, SD, and USB interfaces, and is a data input DIN for SPI (Serial Peripheral Interface), which is a full-duplex, synchronous, serial data link standard across many microprocessors, micro-controllers, and peripherals. SPI enables communication between microprocessors and peripherals and/or inter-processor communication. SPI mode is a subset of the MultiMediaCard protocol. The SPI interface has a chip-select on pin  1  and a data-output to the host on pin  7 . The SPI and MMC interfaces do not use pins  8 ,  9 . 
   For the SD interface, up to four data lines may be used at a time, although only one data line may be used during a particular communication session. Data line DAT 0  is on pin  7 , DAT 1  on pin  8 , DAT 2  on pin  9 , and DAT 3  on pin  1 . 
   When VSD mode is active and the USB protocol selected, serial USB data is transferred bidirectionally over the USB differential data lines D+, D−. The CMD, CLK, and DAT 0  lines can still be connected to the SD processor, allowing 1-bit SD communication to continue while USB is being used. 
   When VSD mode is active and the PCIE protocol selected, serial PCI data is transferred over two pairs of differential data lines. Transmit lines Tp 0 , Tn 0  on pins  2 ,  1  are output by the card and received by the host, while receive lines Rp 0 , Rn 0  on pins  8 ,  9  are output by the host and received by the card. 
   When VSD mode is active and the SATA protocol selected, serial ATA data is transferred over two pairs of differential data lines. A lines A+, A− on pins  2 ,  1  are output by the host and received by the card, while B lines B+, B− on pins  8 ,  9  are output by the SD card and received by the host. SD communication stops while SATA is being used. 
   When VSD mode is active and the Firewire protocol selected, serial IEEE-1394 data is transferred over two pairs of differential data lines. Transmit-pair-A lines TPA, TPA* on pins  2 ,  1  are output by the card and received by the host, while transmit-pair-B lines TPB, TPB* on pins  8 ,  9  are output by the host and received by the card. SD communication stops while IEEE-1394 is being used. 
     FIG. 11  is a table showing signal multiplexing with a 7-pin MMC connector. Older legacy hosts may support only MMC. USB, SD, SPI, and MMC are supported, but not other interfaces such as SATA, IEEE-1394, and PCIE. Although there are 6 MMC signal pins, the MMC interface has an extra, unused pin, for a 7-pin physical interface. Power (VDD) is provided on pin  4 , while grounds are provided on pins  3  and  6 . A clock is input to the card on line  5 , while pin  7  is a serial data I/O DAT 0  for all interfaces. 
   Pin  2  is a bi-directional command CMD line for MMC, SD, and USB interfaces, and is a data input DIN for SPI. The SPI interface has a chip-select on pin  1  and a data-output to the host on pin  7 . The SPI and MMC interfaces do not use pins  8 ,  9 . 
   For the SD interface, up to four data lines may be used at a time, although only one data line may be used during a particular communication session. Data line DAT 0  is on pin  7 , DAT 1  on pin  8 , DAT 2  on pin  9 , and DAT 3  on pin  1 . 
   When VSD mode is active and the USB protocol selected, serial USB data is transferred bidirectionally over the USB differential data lines D+, D− on pins  2 ,  1 . Thus USB can still be supported when only 7 pins are available. 
     FIG. 12  is a table showing pin multiplexing for an extended 13-pin connector. Additional pins  10 – 13  are used as data pins DAT 4 : 7  on an extended SD interface, and on an extended MMC interface. These additional 4 pins can be reserved for the serial-bus interfaces such as for the MMC specification version 4.0. 
     FIG. 13  is a table showing pin multiplexing for a 10-pin Memory Stick system. Rather than use SD, the extended interface could be designed for other card base-protocols, such as Memory Stick (MS). Memory Stick has a 10-pin connector, with power on pins  3  and  9 , and ground on pins  1  and  10 . Pin  8  is a system clock (SCLK) input, while pin  2  is a bus-state (BS) input. Data is carried bidirectionally by DAT 0  on pin  4 , while pin  6  is an insertion (INS) pin that can be pulled up by a resistor on the MS card to indicate that the card has been inserted. 
   Pins  5  and  7  are reserved for MS, but are used by an extension known as MS Pro Duo. MS Pro Duo has a 4-bit data bus, DAT 0 : 3 , using pins  4 ,  3 ,  5 ,  7 , respectively. One less power is available for MS Pro Duo, since pin  3  is used for DAT 1  rather than VCC. 
   For a MS-USB extended mode, pins  4 ,  3  carry the USB differential data pair D+, D−. Other pins can be used for MS or MS Pro Duo signaling. For PCIE extended mode, pins  4 ,  3  carry the PCI transmit differential data pair T+, T−, while pins  7 ,  5  carry the PCI receive differential data pair, R+, R−. Likewise, for SATA extended mode, pins  4 ,  3  carry the SATA transmit differential data pair T+, T−, while pins  7 ,  5  carry the SATA receive differential data pair, R+, R−. For IEEE 1394 extended mode, pins  4 ,  3  carry the 1394 A differential data pair TPA, TPA*, while pins  7 ,  5  carry the 1394 B differential data pair, TPB, TPB*. 
   ALTERNATE EMBODIMENTS 
   Several other embodiments are contemplated by the inventors. For example, a variety of materials may be used for the card substrate, circuit boards, metal contacts, card case, etc. Plastic cases can have a variety of shapes and may partially or fully cover different parts of the circuit board and connector, and can form part of the connector itself. Various shapes and cutouts can be substituted. Pins can refer to flat metal leads or other contactor shapes rather than pointed spikes. 
   Many extended protocols such as PCI-Express, USB, serial ATA, Serial Attached SCSI, or Firewire IEEE 1394 can be used as the second interface. The host may support various serial-bus interfaces, and can first test for USB operation, then IEEE 1394, then SATA, then SA SCSI, etc, and later switch to a higher-speed interface such as PCI-Express. 
   The SD card could be replaced by a Memory Stick (MS) card, a MS Pro card, a MS Duo card, a Mini-SD card, a reduced-size MMC card, etc. A hardware switch could replace some of the card-detection routine steps. For example, a pull-up resistor could be added on the card device to a ground pin to be used as a card-detect line. 
   A special LED can be designed to inform the user which electrical interface is currently in use. For example, if the standard SD interface is in use, then this LED can be turned on. Otherwise, this LED is off. If more than 2 modes exists, then a multi-color LED can be used to specify the mode, such as green for PCI-Express and yellow for USB. 
   Different power-supply voltages may be used. USB and SATA may use a 5-volt supply, while SD and MMC use a 3.3-volt supply, and PCIE uses a 1.5-volt supply. A 3.3-volt supply could be applied to the VCC pin, and an internal voltage converter on the VSD card could generate other voltages, such as 5 volts using a charge pump, and 1.5 volts using a DC-to-DC converter. 
   PCI Express system bus management functions can be achieved by the two differential pairs of the VSD/PCIE interface. Clock signals such as REFCLK+ and REFCLK− are signals that can be added using additional pads. The side band signals of PCIE can be added, such as CPPE#, CPUSB#, CLKREQ#, PERST#, WAKE#, +3.3AUX, SMBDATA, SMBCLK, etc. with additional pads. Also, the approach of using modified PCIE signals can be applied to the design of serially-buffered memory modules of DRAMs. 
   Any advantages and benefits described may not apply to all embodiments of the invention. When the word “means” is recited in a claim element, Applicant intends for the claim element to fall under 35 USC Sect. 112, paragraph 6. Often a label of one or more words precedes the word “means”. The word or words preceding the word “means” is a label intended to ease referencing of claims elements and is not intended to convey a structural limitation. Such means-plus-function claims are intended to cover not only the structures described herein for performing the function and their structural equivalents, but also equivalent structures. For example, although a nail and a screw have different structures, they are equivalent structures since they both perform the function of fastening. Claims that do not use the word “means” are not intended to fall under 35 USC Sect. 112, paragraph 6. Signals are typically electronic signals, but may be optical signals such as can be carried over a fiber optic line. 
   The foregoing description of the embodiments of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. It is intended that the scope of the invention be limited not by this detailed description, but rather by the claims appended hereto.