Compact Flash memory cards

Compact Flash cards were first introduced in 1994 by SanDisk Corporation. They provide full PCMCIA-ATA functionality (which means in practice that each Compact Flash card is simply a PCMCIA card, just in a smaller size!) and ATA/ATAPI-4 compatible TrueIDE functionality. Currently, they are the most widespread standard for this type of memory.


The dimensions of the Compact Flash card are 42.8mm x 36.4mm x 3.3mm - the volume of the Compact Flash card is less than one quarter of the volume of a PCMCIA card. Although it has only 50 pins, the Compact Flash card maintains full compatibility with the PCMCIA ATA standard (a typical PCMCIA card has 68 pins). This means that to adapt the Compact Flash card for use with a PCMCIA slot, a passive adapter with a 68-pin output is sufficient. The given size refers to Type I Compact Flash cards - there are also Type II Compact Flash cards, which have a slightly greater thickness - up to 5mm; a good example of a Type II Compact Flash device is the IBM MicroDrive - a small disk drive with a capacity of up to several GB.

Compact Flash memory cards use memory made (as the name suggests) in flash technology - this means that this memory is "non-volatile" - data is stored for any length of time without the need for any additional power supply. Compact Flash memory cards do not contain moving parts - thus providing significantly better protection for stored data than typical magnetic media (especially all types of disks and floppy disks). The reliability of Compact Flash cards is estimated to be five to ten times higher than that of typical drives used in portable equipment. Additionally, an operating Compact Flash card consumes about 95% less energy than a comparable disk drive. Compact Flash cards provide data transfer speeds of up to 160 MB/s.

Since the Compact Flash standard is compatible with the PCMCIA standard, in addition to memory, there are also other peripheral devices in the Compact Flash format - input/output cards, modems, network cards, USB controllers, laser scanners, Bluetooth cards, and 802.11b WiFi LAN, etc. Cards containing such devices often have an "extended" housing.

Unlike other small memory media, Compact Flash cards operate at both 3.3V and 5V - this means that each card can be freely used in devices powered by either 3.3V or 5V. This makes CF cards an ideal solution for a very wide range of portable devices.

Compact Flash cards, while remaining in this field compliant with the PCMCIA standard, offer the most reliable (among media of this size) connector, which withstands frequent handling (inserting and removing the card from the devices in which it is used).
Compact Flash cards are designed to withstand shocks of up to 2000 G (equivalent to a fall from a height of over three meters) without damage. Under typical operating conditions, CF cards provide completely error-free data storage for at least 100 years.
Due to compatibility with the PCMCIA-ATA standard, CF cards are compatible with the vast majority of operating systems - DOS, Windows, OS/2, Apple System from 7 upwards, most types of UNIX, and many others. All of the mentioned systems work not only with CF memory cards but also with drives compatible with this standard, as well as other peripheral devices.

Compact Flash memory cards have (unlike, for example, SmartMedia cards) a built-in memory controller - containing error correction mechanisms, as well as detection and bypassing of any memory defects. Writes to CF memory cards are most often organized in the FAT16 standard - some, especially older, devices using CF memory cards may not read cards formatted in the FAT32 standard!

New to the market are Type III Compact Flash cards, which have significantly increased read and write speeds.