Overblog Suivre ce blog
Editer l'article Administration Créer mon blog
27 janvier 2011 4 27 /01 /janvier /2011 07:01

The expansion card (also expansion board, adapter card or accessory card) in computing is a printed circuit board that can be inserted into an expansion slot of a computer motherboard to add functionality to a computer system   (Dell XPS M1210 Batteryhttp://www.hdd-shop.co.uk .

One edge of the expansion card holds the contacts (the edge connector) that fit exactly into the slot. They establish the electrical contact between the electronics (mostly integrated circuits) on the card and on the motherboard.

Connectors mounted on the bracket allow the connection of external devices to the card     (Dell Studio XPS 1640 Battery)  .

Depending on the form factor of the motherboard and case, around one to seven expansion cards can be added to a computer system. In the case of a backplane system, up to 19 expansion cards can be installed. There are also other factors involved in expansion card capacity       (Dell Vostro 1710 Battery)       .

For example, most graphics cards on the market as of 2010 are dual slot graphics cards, using the second slot as a place to put an active heat sink with a fan.

Some cards are "low-profile" cards, meaning that they are shorter than standard cards and will fit in a lower height computer chassis  Dell KM958 battery .

(There is a "low profile PCI card" standard that specifies a much smaller bracket and board area). The group of expansion cards that are used for external connectivity, such as anetwork, SAN or modem card, are commonly referred to as input/output cards(or I/O cards)      Dell Studio 1555 battery .

The primary purpose of an expansion card is to provide or expand on features not offered by the motherboard. For example, the original IBM PC did not provide graphics or hard drive capability as the technology for providing that on the motherboard did not exist        Sony VGP-BPS13 battery .

In that case, a graphics expansion card and anST-506 hard disk controller card provided graphics capability and hard drive interface respectively.

In the case of expansion of on-board capability, a motherboard may provide a single serial RS232 port or Ethernet port         Sony VGP-BPS13/B battery .

An expansion card can be installed to offer multiple RS232 ports or multiple and higher bandwidth Ethernet ports. In this case, the motherboard provides basic functionality but the expansion card offers additional or enhanced ports      Sony VGP-BPS13/S battery .


The first microcomputer to feature a slot-type expansion card bus was the Altair 8800, developed 1974-1975. Initially, implementations of this bus were proprietary (such as the Apple II and Macintosh), but by 1982 manufacturers of Intel 8080/Zilog Z80-based computers running CP/M had settled around the S-100 standard          Sony VGP-BPS13A/B battery .

IBM introduced the XT bus, with the first IBM PC in 1981; it was then called the PC bus, as the IBM XT, using the same bus (with slight exception,) was not to be introduced until 1983. XT (a.k.a. 8-bit ISA) was replaced with ISA (a.k.a. 16-bit ISA), originally known as AT bus, in 1984        Sony VGP-BPS13B/B battery .

IBM's MCA bus, developed for the PS/2 in 1987, was a competitor to ISA, also their design, but fell out of favor due to the ISA's industry-wide acceptance and IBM's closed licensing of MCA. EISA, the 32-bit extended version of ISA championed by Compaq, was used on some PC motherboards until 1997, when Microsoft declared it a "legacy" subsystem in the PC 97 industry white-paper  Sony VGP-BPL9 battery .

Proprietary local buses (q.v. Compaq) and then the VESA Local Bus Standard, were late 1980s expansion buses that were tied but not exclusive to the 80386 and 80486 CPU bus. The PC104bus is an embedded bus that copies the ISA bus.

Intel launched their PCI bus chipsets along with the P5-based Pentium CPUs in 1993         Sony VGP-BPS13B/B battery .

The PCI bus was introduced in 1991 as replacement for ISA. The standard (now at version 3.0) is found on PC motherboards to this day. The PCI standard supports Bridging, as many as ten daisy chained PCI buses have been tested. Cardbus, using the PCMCIA connector, is a PCI format that attaches peripherals to the Host PCI Bus via PCI to PCI Bridge     Sony VGP-BPL15 battery .

Cardbus is being supplanted by ExpressCard format. Intel introduced the AGP bus in 1997 as a dedicated video acceleration solution. AGP devices are logically attached to the PCI bus over a PCI-to-PCI bridge. Though termed a bus, AGP usually supports only a single card at a time (Legacy BIOS support issues)      Dell Inspiron E1505 battery .

From 2005 PCI-Express has been replacing both PCI and AGP. This standard, approved in 2004, implements the logical PCI protocol over a serial communication interface. PC104-Plus, Mini PCI, or PCI-104 are often added for expansion on small form factor boards such as Micro ITX      Dell Latitude E6400 battery .

The USB format has become a de facto expansion bus standard especially for laptop computers. All the functions of add-in card slots can currently be duplicated by USB, including Video , networking, storage and audio. USB 2.0 is currently part of the ExpressCard interface and USB 3.0 is part of the ExpressCard 2.0 standard   HP Pavilion dv6000 Battery .

FireWire or IEEE 1394 is a serial expansion bus originally promoted for Apple Inc. Computer expansion replacing the SCSI bus. Also adopted for PCs, often used for storage and video cameras, it has application for networking, video, and audio.

After the S-100 bus, this article above mentions only buses used on IBM-compatible/Windows-Intel PCs   SONY VAIO VGN-FZ Battery .

Most other computer lines that were not IBM compatible, including those from Apple Inc.(Apple II, Macintosh), Tandy, Commodore, Amiga, and Atari, offered their own expansion buses. Apple used a proprietary system with seven 50-pin-slots for Apple II peripheral cards         SONY VAIO VGN-FZ18 Battery ,

then later used theNuBus for its Macintosh series until 1995, at which time they switched to a standard PCI Bus. Generally PCI expansion cards will function on any CPU platform if there is a software driver for that type. PCI video cards and other cards that contain a BIOS are problematic, although video cards conforming to VESA Standards may be used for secondary monitors  SONY VAIO VGN-FZ21E Battery .

DEC Alpha, IBM PowerPC, and NEC MIPS workstations used PCI bus connectors .

Even many video game consoles, such as the Sega Genesis, included expansion buses; at least in the case of the Genesis, the expansion bus was proprietary          SONY VAIO VGN-FW21E Battery ,

and in fact the cartridge slots of many cartridge based consoles (not including the Atari 2600) would qualify as expansion buses, as they exposed both read and write capabilities of the system's internal bus. However, the expansion modules attached to these interfaces        SONY VAIO VGN-NR11S/S Battery ,

though functionally the same as expansion cards, are not technically expansion cards, due to their physical form.

For their 1000 EX and 1000 HX models, Tandy Computer designed the PLUS expansion interface, an adaptation of the XT-bus supporting cards of a smaller form factor      SONY VAIO VGN-NR11M/S Battery .

Because it is electrically compatible with the XT bus (a.k.a. 8-bit ISA or XT-ISA), a passive adapter can be made to connect XT cards to a PLUS expansion connector. Another feature of PLUS cards is that they are stackable. Another bus that offered stackable expansion modules was the "sidecar" bus used by the IBM PCjr       SONY VAIO VGN-NR11Z/S Battery .

This may have been electrically the same as or similar to the XT bus; it most certainly had some similarities since both essentially exposed the 8088 CPU's address and data buses, with some buffering and latching, the addition of interrupts and DMA provided by Intel add-on chips, and a few system fault detection lines (Power Good, Memory Check, I/O Channel Check)  SONY VAIO VGN-NR11Z/T Battery .

Again, PCjr sidecars are not technically expansion cards, but expansion modules, with the only difference being that the sidecar is an expansion card enclosed in a plastic box (with holes exposing the connectors)        Sony VAIO VGN-FZ21E Battery .

ExpressCard is an interface to allow peripheral devices to be connected to a computer, usually a laptop computer. Formerly called NEWCARD, the ExpressCard standard specifies the design of slots built into the computer and of cards which can be inserted into ExpressCard slots      Sony VAIO VGN-FW21E Battery .

The cards containelectronic circuitry and connectors to which external devices can be connected. The ExpressCard standard replaces the PC Card (also known as PCMCIA or CardBus) standards.

ExpressCard plug-in hardware available includes connect cards, FireWire 800 (1394B), USB 3.0, 1Gb/sec Ethernet Sony VAIO VGN-NR11S/S Battery ,

Serial ATA external disk drives, solid-state drives, external enclosures for desktop size PCI Express graphics cards, wireless network interface cards, TV tuner cards, common access card (CAC) readers, and soundcards. Media remote control units are available that use the ExpressCard slot to store and recharge        Sony VAIO VGN-NR11Z/S Battery .


The Personal Computer Memory Card International Association (PCMCIA) developed both the ExpressCard standard and the PC Card standards. The host device supports both PCI Express and USB 2.0 connectivity through the ExpressCard slot; cards can be designed to use either mode      Sony VAIO VGN-NR11M/S Battery .

The cards are hot-pluggable. This is an open standard by ITU-T definition which can be obtained from the ExpressCard website. The documentation is free to members of PCMCIA, and US$2,500 to non-members as of 2009    Sony VAIO VGN-NR11Z/T Battery .

Form factors

The ExpressCard standard specifies two form factors, ExpressCard/34 (34 mm wide) and ExpressCard/54 (54 mm wide, in an L-shape)—the connector is the same on both (34 mm wide)       SONY VAIO VGN-FZ180E Battery .

Standard cards are 75 mm long (10.6 mm shorter than CardBus) and 5 mm thick, but may be thicker on sections that extend outside the standard form for antennas, sockets, etc.

The 34 mm slot accepts only 34 mm cards      SONY VAIO VGN-FZ220E Battery .

The 54 mm slot accepts both 34 mm and 54 mm cards. A diagonal guide in the rear of the 54 mm slot guides 34 mm cards to the connector. Adapters are available for connecting an ExpressCard/34 card to a CardBus (but not 16-bit PC Card) slot    SONY VAIO VGN-FZ340E Battery .

Comparison to other standards

The older PC Cards came in 16-bit and the later 32-bit CardBus designs. The major benefit of the ExpressCard over the PC card is more bandwidth, due to the ExpressCard's direct connection to the system bus over a PCI Express ×1 lane and USB 2.0, while CardBus cards only interface with PCI      SONY VAIO VGN-FZ430E Battery .

The ExpressCard has a maximum throughput of 2.5 Gbit/s through PCI Express and 480 Mbit/s through USB 2.0 dedicated for each slot, while all CardBus devices connected to a computer share a total 1.06 Gbit/s bandwidth.

The ExpressCard standard specifies voltages of either 1.5 V or 3.3 V; CardBus slots can use 3.3 V or 5.0 V   SONY VAIO VGN-FZ460E Battery .

The [ExpressCard FAQ claims lower cost, better scalability, and better integration with motherboard chipset technology than Cardbus. PCMCIA devices can be connected to an ExpressCard slot via an adapter          SONY VAIO VGN-FZ480E Battery .

When the PC Card was introduced, the only other way to connect peripherals to a laptop computer was via obsolescent RS232 and parallel ports of limited performance, so it was widely adopted for many peripherals. More recently, virtually all laptop equipment has 480 Mbit/s Hi-Speed USB 2.0 ports     SONY VAIO VGN-FZ4000 Battery ,

and most types of peripheral which formerly used a PC Card connection are available for USB, making the ExpressCard less necessary than the PC Card was in its day. Some laptop computers do not have an ExpressCard slot. For example, as of the second half of 2009 the only Apple laptop computer with an ExpressCard slot is the 17-inch MacBook Pro         SONY VAIO VGN-FZ31E Battery .


An ExpressCard slot had been commonly included on high-end laptops made since 2006, but has now been superseded by USB 3.0. According to the statement on the PCMCIA website, "The PCMCIA Association has been dissolved and the San Jose office closed  SONY VAIO VGN-FZ31B Battery .

All activities and Standards, including the ExpressCard Standard and PC Card Standard, will be managed going forward by the USB Implementer's Forum." The information below is out of date        SONY VAIO VGN-FZ31J Battery .

  • Hewlett-Packard began shipping systems with ExpressCard in November 2004.
  • Lenovo integrated the slot into their flagship ThinkPad T43 in May 2005         SONY VAIO VGN-FZ31M Battery .
  • Dell Computer also incorporates this in their Precision (the 17 in models have them exclusively, the 15 in Precisions have both express card and PCMCIA Card slots), Inspiron, Latitude (Latitude D-series have PCMCIA card slots. The D820/D830 have both ExpressCard and PCMCIA card slots), Studio, Vostro and XPS Laptop product lines     SONY VAIO VGN-FZ31Z Battery .
  • Fujitsu-Siemens began shipping systems with ExpressCard in mid 2005.
  • Apple Inc. included single ExpressCard/34 slots in every MacBook Pro notebook computer from January 2006 through June 2009        SONY VAIO VGN-FZ38M Battery .
  • At the June 8, 2009Apple Worldwide Developers Conference the company announced that the 15-inch and 13-inch MacBook Pro models would replace the ExpressCard slot with a Secure Digital card slot, while retaining the ExpressCard slot on the 17-inch model     SONY VGP-BPS8 Battery .
  • ASUS has also replaced the PC Card slot with an ExpressCard slot on many of its new models.
  • Sony also began shipping systems with ExpressCard with its new laptop VGN-SZ, VGN-NS, VPC and FW product line.
  • The Acer Aspire laptop series also has a single ExpressCard/54 slot on most new models  SONY VGP-BPS13 Battery .
  • Panasonic incorporates ExpressCard/54 slots in all the fully rugged and semi-rugged models of their Toughbook brand of laptop computers.
  • Gateway notebooks (ML3109 and later) also ship with ExpressCard/54 interfaces   SONY VGP-BPS13/S Battery .

Because of the lack of backward compatibility, some laptop manufacturers have chosen to release models incorporating both CardBus (PCMCIA, PC Card) and ExpressCard slots. These include certain models of Acer Aspire, Toshiba Satellite, Dell Latitude and Precision, MSI S42x and Lenovo ThinkPad Z60m, R52, T60 and R61       SONY VGP-BPS13A/B Battery .

A large number of ExpressCard devices were presented at the CeBit trade show in Germany in March 2005. In November 2006, Belkin announced that it is launching the first ExpressCard docking station, which uses the PCIe part of an ExpressCard connection to enable 1600x1200 video and the USB part to provide USB, audio and network ports   SONY VGP-BPS13B/B Battery .

This points to the ability for ExpressCard to allow more capable non-OEM docking stations for laptop computers.

In 2007, Sony introduced its Vaio TZ model, which incorporates ExpressCards. Also the Sony Vaio FZ and Vaio Z series have the ExpressCard/34 Slot integrated in them     SONY VGP-BPS13A/S Battery .

Sony also uses the ExpressCard/34 form factor for the flash memory modules in its XDCAM EX/SxS based camcorders, making the copying of video data between these cameras and ExpressCard-equipped laptops easier. For this reason, Sony also offers a USB-based SxS reader for desktop computers    SONY VGP-BPS13AS Battery .

The new Toshiba Satellite P and X 200/205 series of laptops and desktop replacements have an ExpressCard/34 slot since April 2007.

ExpressCard 2.0

The ExpressCard 2.0 standard was delivered March 4, 2009 at CeBIT in Hannover    Dell Inspiron 1320n Battery .

It is expected to have a raw bandwidth of 5 Gbit/s (transfer speed 500 MB/s or 0.5 GB/s), which is ten times USB 2.0 (0.48 Gbit/s or 60 MB/s), and includes USB 3.0 (5.0 Gbit/s or 625 MB/s or 0.625 GB/s). It complies with PCI-Express 2.0 and SuperSpeed USB, which is part of the USB 3.0 specification       Dell Inspiron 1464 Battery .

It is backwards compatible with current ExpressCard modules and 2.0 ExpressCard modules will work in current slots. ExpressCard 2.0 products are expected to be in the market in late 2010.

CompactFlash (CF) is a mass storage device format used in portable electronic devices      Dell Inspiron 1564 Battery .

For storage, CompactFlash typically uses flash memory in a standardized enclosure.

The format was first specified and produced by SanDisk in 1994. The physical format is now used for a variety of devices  Dell Inspiron 1764 Battery .

CompactFlash became the most successful of the early memory card formats, outliving Miniature Card, SmartMedia, and PC Card Type I in mainstream popularity. The memory card formats that came out after the introduction of CompactFlash, such as SD/MMC, various Memory Stick formats, xD-Picture Card, offered stiff competition      Dell Studio 1450 Battery .

Most of these cards are significantly smaller than CompactFlash while offering comparable capacity and read/write speed. Proprietary memory card formats intended for use in the field of professional audio and video, such as P2 and SxS, are physically larger, faster, and significantly more expensive     Dell Studio 1457 Battery .

CompactFlash remains popular, and has even experienced something of a comeback. For example, in 2008 Sony chose CompactFlash as the recording media for use in the HVR-MRC1K tapeless video recorder instead of using smaller MemoryStick cards or expensive SxS cards    Dell Latitude D610 Battery .

In 2010 Canon chose CompactFlash as the recording media for use in its new lineup of professional high definition video cameras.

In November 2010, Sandisk, Sony and Nikon proposed a next generation card format targeted at high-definiton camcorders and high-resolution digital photo cameras         Toshiba NB100 Battery ;

not backward compatible, the proposed format would come in a similar form factor as CF/CFast but be based on PCI Express instead of ATA and would offer read speed of 500 MB/s and storage capabilities beyond 2 TiB. It remains unclear, if the CFA will adopt this proposal         Toshiba Satellite M65 battery ,

as CF 5.0 already supports media up to 128 PiB and CF 6.0 adds speeds up to 167 MB/s, while the SATA-based CFast already defines speeds up to 300 MB/s.


There are two main subdivisions of CF cards, Type I (3.3 mm thick) and the thicker Type II (CF2) cards (5 mm thick)  Toshiba Satellite M60 battery .

The CF Type II slot is used byMicrodrives and some other devices, such as the Hasselblad CFV Digital Back for the Hasselblad series of medium format cameras. There are four main speeds of cards including the original CF, CF High Speed (using CF+/CF2.0), a faster CF 3.0 standard and a yet faster CF 4.0 standard that is being adopted as of 2007    Dell Latitude D830 Battery .

The thickness of the CF card type is dictated by the preceding PC Card standard.

CompactFlash was originally built around Intel's NOR-based flash memory, but has switched to NAND technology.CF is among the oldest and most successful formats, and has held a niche in the professional camera market especially well   Dell Latitude D620 Battery .

It has benefited from both a better cost to memory-size ratio than other formats, (for much of its life) and generally from greater available capacity than other formats.

CF cards can be used directly in a PC Card slot with a plug adapter, used as an ATA (IDE) or PCMCIA storage device with a passive adapter or with a reader, or attached to other types of ports such as USB or FireWire    Dell Inspiron Mini 10 Battery .

As some newer card types are smaller, they can be used directly in a CF card slot with an adapter. Formats that can be used this way include SD/MMC, Memory Stick Duo, xD-Picture Card in a Type I slot, and SmartMedia in a Type II slot, as of 2005. Some multi-card readers use CF for I/O as well     Sony VGN-FW11S Battery .

Flash memory, regardless of format, is limited to a finite number of erase/write cycles for any "block," before that block can no longer be written to successfully. Typically, the controller in a CompactFlash device attempts to prevent premature wear of a sector by choosing the write location for a piece of data so as to spread the writing over the device   Sony VGN-FW11M Battery .

This process is called wear leveling.

When using CompactFlash in ATA mode as a hard drive replacement, wear leveling becomes critical. The advanced CompactFlash controllers spread the wear-leveling across the entire drive allowing all blocks to participate   Sony VGN-FW139E/H battery .

The more advanced CompactFlash controllers will move data that rarely changes to ensure all blocks wear evenly.

Technical details

CompactFlash interface is a 50 pin subset of the 68 pin PCMCIA connector       Dell Latitude E5400 Battery .

"It can be easily slipped into a passive 68-pin PCMCIA Type II to CF Type I adapter that fully meets PCMCIA electrical and mechanical interface specifications."The Compactflash interface operates, depending on the state of a mode pin on powerup, as either 16-bit PC Card (0x7FF address limit) or as an IDE (PATA) interface       Dell Latitude E4200 Battery .

CompactFlash IDE mode defines an interface that is smaller than, but electrically identical to, the ATA interface. That is, it appears to the host device as if it were a hard disk. The CF device contains an ATA controller. CF devices operate at 3.3 volts or 5 volts, and can be swapped from system to system   Dell Inspiron 300M Battery .

CompactFlash supports C-H-S and 28-bit Logical block addressing (CF 5.0 introduced support for LBA-48). CF cards may be set to master or slave, but have issues sharing the IDE bus. CF cards with flash memory are able to cope with extremely rapid changes in temperature    Dell Vostro A840 Battery .

Industrial versions of flash memory cards can operate at a range of ?45 to +85 °C.

NOR-based flash has lower density than newer NAND-based systems, and CompactFlash is therefore the physically largest of the three memory card formats introduced in the early 1990s, being derived from the JEIDA/PCMCIA Memory Card formats   Dell Studio 1737 battery .

The other two are Miniature Card (MiniCard) andSmartMedia (SSFDC). However, CF did switch to NAND type memory later. The IBM Microdrive format implements the CF Type II interface, but is not solid-state memory. Hitachi and Seagate also make microdrives  Dell Inspiron E1505 battery .


CompactFlash IDE (ATA) emulation speed is usually specified in "x" ratings, e.g. 8x, 20x, 133x. This is the same system used for CD-ROMs and indicates the maximum transfer rate in the form of a multiplier based on the floppy disk, which is 150 KB/s   Dell RM791 battery .

, KB/sec

where R = transfer rate, K = speed rating. For example, 133x rating means transfer speed of: 133 * 150 kB/s = 19,950 kB/s ~ 20 MB/s.

These are manufacturer speed ratings. Actual transfer speed may be higher, or lower, than shown on the card depending on several factors   Dell XPS M1530 battery .

Solid State

For reads, the onboard controller first powers up the memory chips from standby. Reads are usually in parallel, error correction is done on the data, then transferred through the interface 16 bits at a time. Error checking is required due to soft read errors  Dell XPS M2010 battery .

Writes require powerup from standby, wear leveling calculation, a block erase of the area to be written to, ECC calculation, write itself (an individual memory cell read takes around 100 ns, a write to the chip takes 1ms+ or 10,000 times longer)   Acer Aspire One battery .

Since the USB 2.0 interface is limited to 60 MB/sec and lacks bus mastering hardware, USB implementation results in slower access.

A direct motherboard connection is often limited to 33 MB/sec because IDE to CF adapters lack high speed ATA (66 MB/sec plus) cable support. Power on from sleep/off takes longer than power up from standby        Toshiba Satellite P10 Battery .

Magnetic Media

Many 1-inch (25 mm) hard drives (often referred to by the trademarked name "Microdrive") typically spin at 3600 rpm so rotational latency is a consideration, as is spin-up from standby or idle. Seagate's 8 GB ST68022CF drive spins up fully within a few revolutions but power draw can reach up to 350 milliamps and runs at 40-50 mA average power   SONY VGN-FZ210CE Battery .

Its average seek time is 8 ms and can sustain 9 MB/s read and write, and has an interface speed of 33 MB/sec. Hitachi's 4 GB Microdrive is 12 ms seek, sustained 6 MB/sec.

Capacities and compatibility

Since flash memory is generally produced in capacities that are multiples of powers of 2, IEC standard binary prefixes are used throughout this article   Dell Precision M70 Battery .

The CF Specification (support 28 bit LBA) can support capacities up to 137 GB (128 GiB). Prior to 2006, CF drives using on magnetic media offered the highest capacities. But with the advent of 16 GiB and higher solid-state CF cards, they have offered the higher capacities    Toshiba Satellite L305 Battery .

Though, as of 2011, solid-state drives (SSDs) had supplanted both kinds of CF dives for large capacity requirements. Consequently, commercially available solid-state CF cards rarely go above 64 GiB, and 1-inch hard drives generally top out at 8 GiB       Toshiba Satellite T4900 Battery .

Solid State Capacities

SanDisk announced its 16 GiB Extreme III card at the Photokina trade fair, in September, 2006.That same month, Samsung announced 16, 32 and 64 GiB CF cards.Two years later, in September, 2008, Pretec announced 100GB cards      Toshiba PA3399U-2BRS battery .

Magnetic Media Capacities

Seagate announced a 5 GiB "1-inch hard drive" in June, 2004 , and an 8 GiB version in June, 2005.


An important consideration for use in systems is reliability     Toshiba Satellite A200 Battery .

The original PC Card memory cards were battery backed RAM then NOR flash. At the time NOR flash had a write endurance of 10,000 cycles (but no read liability). The currently used NAND flash has an endurance of 1,000,000 writes per location (less reliable than magnetic media) before hard failure and is prone to frequent soft read errors       Toshiba Satellite 1200 Battery .

The CompactFlash card includes error checking and correcting (ECC) and wear leveling circuitry that is transparent to the user, although it may slow data access. Car PC Hacks suggests disabling Windows swap file and using its Enhanced Write Filter (EWF) to eliminate unnecessary writes to CF storage media        Toshiba Satellite M300 Battery .

However, EWF is available only in XP Embedded, not XP Professional, Home, or Media Editions versions of Windows.

Flash memory devices are non-volatile and solid-state, and thus are as, or more, robust than rotating media drives. The ST68022CF Microdrive is shock rated at 175G operating and 750G non-operating       SONY VGP-BPS13A/Q Battery .

Small cards consume around 5% of the power required by small disk drives and still have reasonable transfer rates of over 45 MB/s for the more expensive 'high speed' cards. Manufacturers warning on flash memory used for ReadyBoost indicates a current draw in excess of 500 mA     SONY VGP-BPS13A/Q Battery .


Originally, flash memory used Flash File System and JFFS to work around low level issues with the technology. Since hardware now hides much of the complexity from the end user, Compactflash disk storage for use in consumer devices is typically formatted as FAT12 (for media up to 16 MiB)        SONY VGP-BPS13B/Q Battery ,

FAT16 (for media up to 2 GiB, sometimes up to 4 GiB) and FAT32 (for media larger than 2 GiB) which not only works with end user computers but also is simple enough for limited processing ability of processors in devices such as cameras.

There are varying levels of compatibility among FAT32-compatible cameras, MP3 players, PDAs, and other devices  SONY VGP-BPS13B/Q Battery .

While any device that claims FAT32-capability should read and write to a FAT32-formatted card without problems, some devices are tripped up by cards larger than 2 GB that are completely unformatted, while others may take longer to apply a FAT32 format  SONY VGP-BPS13/Q Battery .

The way many digital cameras update the file system as they write to the card creates a FAT32 bottleneck. Writing to a FAT32-formatted card generally takes a little longer than writing to a FAT16-formatted card with similar performance capabilities   SONY VGP-BPS13/Q Battery .

For instance, the Canon EOS 10D writes the same photo to a FAT16-formatted 2 GB CompactFlash card somewhat faster than to a same speed 4 GB FAT32-formatted CompactFlash card, although the memory chips in both cards have the same write speed specification      SONY VGP-BPS21A/B Battery .

Although FAT16 is more wasteful of disk space with its larger clusters, it works better with the write strategy that flash memory chips require.

The cards themselves can of course be formatted with any type of file system such as JFS and NTFS  SONY VGP-BPS21/S Battery .

It can be divided into partitions as long as the host device can read them. CompactFlash cards are often used instead of hard drives in embedded systems, dumb terminals and various small form-factor PCs that are built for low noise output or power consumption  SONY VGP-BPS21B Battery .

CompactFlash cards are often more readily available and smaller than purpose-built solid-state drives and often have faster seek times than hard drives        SONY VGP-BPS21A Battery .

CF+ and Compact Flash specification revisions

When CompactFlash was first being standardized, even full-sized hard disks were rarely larger than 4 GB in size, and so the limitations of the ATA standard were considered acceptable        SONY VGP-BPS21 Battery .

However, CF cards manufactured after the original Revision 1.0 specification are available in capacities up to 128 GiB. While the current revision 6.0 works in [P]ATA mode, future revisions are expected to implement SATA mode          Sony VGP-BPS21A/B Battery .

  • CompactFlash Revision 1.0 (1995), 8.3 MB/s (PIO mode 2), support for up to 128 GiB (137 GB) storage space.
  • CF+ and CompactFlash Revision 2.0 (2003) added an increase in speed to 16.6 MB/s data-transfer (PIO mode 4). At the end of 2003, DMA 33 transfers were added as well, available since mid 2004       Sony VGP-BPS21B Battery .
  • CF+ and CompactFlash Revision 3.0 (2004) added support for up to a 66 MB/s data transfer rate (UDMA 66), 25 MB/s in PC Card mode, added password protection, along with a number of other features. CFA recommends usage of the FAT32 filesystem for storage cards larger than 2 GiB          Sony VGP-BPS21A Battery .
  • CF+ and CompactFlash Revision 4.0 (2006) added support for IDE Ultra DMA Mode 6 for a maximum data transfer rate of 133 MB/s (UDMA 133).
  • CF+ and CompactFlash Revision 4.1 (2007) added support for Power Enhanced CF Storage Cards    Sony VGP-BPS21 Battery.
  • CompactFlash Revision 5.0 (2010) added a number of features, including 48-bit addressing (supporting 128 Petabyte of storage), larger block transfers of up to 32 Megabytes, quality-of-service and video performance guarantees, and other enhancements  Sony Vaio PCG-5G2L Battery .
  • CompactFlash Revision 6.0 (November 2010) added UltraDMA Mode 7 (167MB/s), ATA-8/ACS-2 sanitize command, TRIM and an optional card capability to report the operating temperature range of the card.


CE-ATA is a Serial ATA interface based on the MultiMediaCard standard       Sony Vaio PCG-5G3L Battery . 


A variant of CompactFlash, known as CFast, is based on the Serial ATA bus, rather than the Parallel ATA/IDE bus all previous versions of CompactFlash are designed for            Sony Vaio PCG-5J1L Battery .

These cards support a higher maximum transfer rate than current CompactFlash cards. As of 2009, SATA (SATA II) supports transfer rates up to 300 MB/s while PATA is limited to 133 MB/s usingUDMA 6. Few, if any, current flash memory devices support speeds greater than 133 MB/s, but when enough are teamed together in parallel, they can exceed 300 MB/s  Sony Vaio PCG-5K2L Battery .

CFast cards are not physically or electrically compatible with CF cards, requiring new card readers and new digital cameras to take advantage of them. However, since SATA can emulate PATA on the software side, CFast cards don't require new driver software in operating systems    Sony Vaio PCG-5J2L Battery ,

but writing new drivers to use AHCI instead of PATA emulation will almost always result in significant performance gains. CFast cards use a 7-pin SATA data connector (identical to the standard SATA connector), but a 17-pin power connector that appears incompatible with the standard 15-pin SATA power connector,so an adaptor will be required to connect CFast cards in place of standard SATA hard drives      Sony Vaio PCG-5K1L Battery .

The first CFast cards reached the market in late 2009. At CES 2009, Pretec showed a 32 GB CFast and announced that they should reach market within a few months.

Type I and Type II

The only physical difference between the two types is that Type I devices are 3.3 mm thick while Type II devices are 5 mm thick  Sony Vaio PCG-5L1L Battery .

Electrically, the two interfaces are the same except that Type I devices are permitted to draw up to 70 mA supply current from the interface, while type II devices may draw up to 500 mA.

The vast majority of all Type II devices are Microdrives and other miniature hard drives       Sony Vaio PCG-6S2L Battery .

Flash based Type II devices are rare but a few examples do exist. Compact Flash — Secure Digital adapters usually are Type II. [31]Even the largest capacity cards commonly available are Type I cards. Most card readers will read both formats, with the exception of some early CF based cameras or poorer quality USB card readers where the slot is too small   Sony Vaio PCG-6S3L Battery .

Various manufacturers of 4 GB Compact Flash cards such as Sandisk, Toshiba, Alcotek and Hynix have developed devices that support mainly type I slots. Some of the latest DSLRs, like the Nikon D700, have also dropped Type II support   Sony Vaio PCG-6V1L Battery .


Microdrives are tiny hard disks—about 25 mm (1 inch) wide—packaged with a CompactFlash Type II form factor and interface. They were developed and released in 1999 by IBM with a capacity of 170MB       Sony Vaio PCG-6W1L Battery .

IBM sold its disk drive division, including the Microdrive trademark, to Hitachi in December 2002. There are now other brands of Microdrives (such as Seagate, Sony, etc.), and, over the years, these have become available in increasing capacities (up to 8 GB as of late 2008)        Sony Vaio PCG-6W2L Battery .

While these drives fit into and work in any CF II slot, the early versions drew more current (500 mA maximum) than flash memory (100 mA maximum). However current Microdrives use less than 200 mA for reads and writes (300 mA peak), and some flash devices used for high speed data e.g      Sony Vaio PCG-6W3L Battery .

Readyboost (memory can't power down to standby) draw more than the USB standard allows (500 mA). As they are mechanical devices, Microdrives are susceptible to damage from physical shock or temperature changes. However, Microdrives are not subject to the write cycle limitation inherent to flash memory      Sony Vaio PCG-7111L Battery .

The iPod mini, Nokia N91, iriver H10 (5 or 6 GB model), PalmOne LifeDrive, and Rio Carbon all used a CF Microdrive to store data.

Compared to other portable storage

  • CF cards are considered more rugged and durable to many "in the field" photographic shocks, impacts and accidents   Sony Vaio PCG-7112L Battery .
  • CompactFlash cards are capable of withstanding more physical damage in comparison to other, flimsier designs.
  • Due to their compatibility with IDE/ATA they are used in many embedded systems as solid-state drives. In early 2008 the CFA demonstrated CompactFlash cards with a built in SATA interface       Sony Vaio PCG-7113L Battery .
  • Several companies make adapters to allow CF cards to be connected to PCI, IDE, 44-pin laptop mini-IDE, and SATA connections, allowing a CF card to act as a solid-state drive with virtually any operating system or BIOS, and even in a RAID configuration      Sony Vaio PCG-7133L Battery .
  • CompactFlash does not have any built in DRM or cryptographic features like on some USB flash drives and other card formats. The lack of such features contributes to the openness of the standard since other memory card standards with such features are subject to restrictive licensing agreements      Sony Vaio PCG-7Z2L Battery .
  • CF cards are available at higher storage capacities than some smaller flash memory cards.
  • CompactFlash lacks the mechanical write protection switch that some other devices have, as seen in a comparison of memory cards with exception of industrial CF-card models (AC60 Turbo/ AC73 and AC75 series) made by CoreSolid Storage   Sony Vaio PCG-8Y1L Battery .
  • In the case of improper insertion, a card can potentially cause damage to the device receiving the card. However, this rarely happens as slots are usually designed to prevent this.
  • CompactFlash's large dimensions in comparison to other cards limits its feasibility in very slim devices  Sony Vaio PCG-8Y2L Battery .
  • The large card slot consumes devices' valuable internal space, especially in point and shootdigital cameras. On another hand, a CompactFlash card cannot be lost as easily as a tiny MicroSD card, and insertion and removal may be easier with a larger card  Sony Vaio PCG-8Z1L Battery .


There is extensive marketplace competition for sales of all brands of flash memory. As a result counterfeiting is quite widespread  Sony Vaio PCG-8Z2L Battery .

Under their own brand, or while imitating another, unscrupulous flash memory card manufacturers may sell low-capacity cards formatted to indicate a higher capacity, or else use types of memory that are not intended for extensive rewriting   Sony VAIO PCG-5G2L Battery .

The gigabyte (pronounced /?????ba?t/ GIG-?-byt) is a multiple of the unit byte for digital information storage. The prefix giga means 109 in theInternational System of Units (SI), therefore 1 gigabyte is 1000000000bytes. The unit symbol for the gigabyte is GBor Gbyte, but not Gb(lower case b) which is typically used for the gigabit        Sony VAIO PCG-5G3L Battery .

Historically, the term has also been used in some fields of computer science and information technology to denote the gibibyte, or1073741824 (10243 or 230) bytes. The Institute of Electrical and Electronics Engineers (IEEE) defined the unit accordingly for the use in power switchgear     Sony VAIO PCG-5J1L Battery .

In 2000, however, IEEE adopted the International Electrotechnical Commission (IEC) recommendation, which uses the metric prefix interpretation.

Today the usage of the unit gigabyte continues to depend on the context         Sony VAIO PCG-5K2L Battery .

When referring to disk storage capacities it usually means 109bytes.This also applies to data transmission quantities over telecommunication circuits, as the telecommunications and computer networking industries have always used the SI prefixes with their standards-based meaning        Sony VAIO PCG-5J2L Battery .

When referring to RAM sizes it most often (see binary prefix adoption) has a binary interpretation of 10243 bytes, i.e. as an alias for gibibyte. File systems and software often list file sizes or free space in some mixture of SI units and binary units; they sometimes use SI prefixes to refer to binary interpretation      Sony VAIO PCG-5K1L Battery

– that is using a label of gigabyte or GB for a number computed in terms of gibibytes (GiB), continuing the confusion.

In order to address this the International Electrotechnical Commission has been promoting the use of the term gibibyte for the binary definition      Sony VAIO PCG-5L1L Battery .

This position is endorsed by other standards organizations including the IEEE, the International Committee for Weights and Measures (CIPM) and the U.S. National Institute of Standards and Technology (NIST), but the binary prefixes have seen limited acceptance      Sony VAIO PCG-6S2L Battery .

The JEDEC industry consortium continues to recommend the IEEE 100 nomenclature of using the metric prefixes kilo, mega and giga in their binary interpretation for memory manufacturing designations.

Since the early 2000s most consumer hard drive capacities are grouped in certain size classes measured in gigabytes  Sony VAIO PCG-6S3L Battery .

The exact capacity of a given drive is usually some number above or below the class designation. Although most manufacturers of hard disk drives and flash-memory disk devices define 1 gigabyte as 1000000000bytes, software like Microsoft Windows reports size in gigabytes by dividing the total capacity in bytes by 1073741824   Sony VAIO PCG-6V1L Battery ,

while still reporting the result with the symbol "GB". This practice is a cause of confusion, as a hard disk with a manufacturer-rated capacity of 400 gigabytes might be reported by the operating system as only "372 GB", for instance. Other software, like Mac OS X 10.6 and some components of the Linux kernel  measure using the decimal units   Sony VAIO PCG-6W1L Battery .

The JEDEC memory standards uses the IEEE 100 nomenclatures which defines a gigabyte as 1073741824bytes (or 230 bytes).

The difference between units based on SI and binary prefixes increases as a semi-logarithmic (linear-log) function—for example, the SI kilobyte value is nearly 98% of the kibibyte, a megabyte is under 96% of a mebibyte   Sony VAIO PCG-6W2L Battery ,

and a gigabyte is just over 93% of a gibibyte value. This means that a 300 GB (279 GiB) hard disk is indicated only as 279 GB. As storage sizes increase and larger units are used, this difference becomes even more pronounced. Some legal challenges have been waged over this confusion such as a suit against Western Digital       Sony VAIO PCG-6W3L Battery .

Western Digital settled the challenge and added explicit disclaimers to products that the usable capacity may differ from the advertised capacity.

Because of its physical design, computer memory is addressed in multiples of base 2    Sony VAIO PCG-7111L Battery ,

thus, memory size at the hardware level can always be factored by a power of two. It is thus convenient to use binary units for non-disk memory devices at the hardware level, for example, in using DIMM memory boards. Software application, however, allocate memory  Sony VAIO PCG-7112L Battery ,

usually virtual memory in varying degrees of granularity as needed to fulfill data structure requirements, and binary multiples are usually not required. Other computer measurements, like storage hardware size, data transfer rates, clock speeds,operations per second, etc., do not depend on an inherent base, and are usually presented in decimal units      Sony VAIO PCG-7113L Battery.

Partager cet article

Repost 0
Published by batterys - dans Laptop Battery
commenter cet article