PCMCIA CompactFlash Memory Cards FAQ and Information
Introduction
SanDisk introduced CompactFlash memory cards in 1994 providing device manufacturers with a smaller form factor than PC Card (hence a "Compact Flash"). What they introduced was removable storage that was considerably smaller than PC Card, but retained essentially the same pinout configuration. While PC Card is a 68 pin parallel bus, and CompactFlash is only 50 pin, the difference is irrelevant as the 18 pins not found on CompactFlash are unused and or reserved pins still undefined. This is why PC Card to CompactFlash Card media adapters are a passive pin out only.
- Contents
- What is the difference between Type I and Type II CompactFlash?
- Is it CompactFlash or Compact Flash?
- What is CFII+ CompactFlash?
- What are CF+ and CF+ I/O CompactFlash?
- What is Type II CompactFlash?
- Are Hitachi and Hitachi Microdrives or Seagate 1" drives considered CompactFlash?
- What are High Speed or X-Speed cards?
- What is the difference between FAT-16 and FAT 32, why do cards greater than 2GB require FAT-32?
- What it is Write Acceleration Technology?
- Is there a industry or standards body for CompactFlash?
What is the difference between Type I and Type II CompactFlash?
As with PC Card, the Type I/II designation only has to do with the thickness of the card. Type I cards are 3.3mm thick, while Type II or 5.0mm thick. Both are 43mm in width and 36 mm in height. A Type I card will fit into a Type II slot or adapter, while the converse is naturally not the case.
CompactFlash Type I: 36.4mm x 42.8mm x 3.3mm (LWH) 50 pin CompactFlash Type II: 36.4mm x 42.8mm x 5.0mm (LWH) 50 pin PC Card Type II: 85.6mm x 54.0mm x 5.0mm (LWH) 68 pin
Is it CompactFlash or Compact Flash?
It is CompactFlash, see CompactFlash Association (CFA).
What is CFII+ CompactFlash?
The CompactFlash Association had some trouble when the CFII and CF+ designations were first coined. CFII+ is both a Type II form factor and an I/O capable card. It was first used to describe Microdrives and then later for I/O cards. The CFA later designated I/O style cards as CF+ I/O The following entries explain this more in depth for each designation
What are CF+, CFII+ and CF+ I/O CompactFlash?
CF+ essentially extends the CompactFlash standard to handle 16-bit I/O other than the PC Card ATA command set. This means in addition to storage media, CF+ I/O cards are available for a variety of functionality including RS-232 serial I/O, 802.3 10Base-T Ethernet, and other applications. Typically hand-held computers are the only devices that utilize this functionality. Although a low cost PC Card to CompactFlash adapter often allows use of these cards in laptops and other computers with PC Card slots.
Synchrotech's P312 PCI Bus to CompactFlash Type I-II Read-Writer Internal Rear Low Profile allows full use of CF+ style devices in PCI equipped computers.
- Fastest CompactFlash Reader
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- PCM-CR-FW81ECF-02
- CFFire800 Pro FireWire 800 to CompactFlash Drive Read-Writer
- Blazing fast UDMA 6 and PIO 4 capable, CFFire800 is a professional's choice and the best option for high end CompactFlash Cards.
- CompactFlash Cards
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- PCM-CFSY- Series
- Synchrotech Standard and High Speed CompactFlash Memory Cards
- Economical 24X general purpose and 40X/100X/120X High Speed cards
What is Type II CompactFlash?
Type II CompactFlash is 5.0mm thick. Devices with Type II slots can accept either Type I or II CompactFlash, while devices with Type I slots accept Type I CompactFlash exclusively.
Are Hitachi and Hitachi Microdrives or Seagate 1" drives considered CompactFlash?
Yes. Microdrives and similar products conform to the CFII+ specification are usable in any slot that takes Type II CompactFlash. Advantages of rotating media devices are that they are much better priced per megabyte. Disadvantages are that they are somewhat fragile and don't perform as well as high end solid state cards.
What are High Speed or X-Speed cards?
When CompactFlash was first designed, devices and applications didn't really exceed the read-write speeds of the first generation cards. This changed as digital camera resolutions grew, and uses of CompactFlash in embedded systems and other speed dependent devices became common. There are two main factors in how fast a CF card can write and read data. The first is the flash memory cells themselves. The second is the IDE controller chip on the card, which coordinates reads, writes, erasure, error correction, etc. As flash memory and more importantly controllers have gotten faster, CF cards perform much better. Vendors like Lexar Media, Inc. began using a the same speed rating that CD-RW manufacturers use to designate the speed of CD Burners with 1X being a write speed of 150KB/sec. The following is a table of common CompactFlash card write speeds.
| Speed | KBytes/s | MBytes/s |
|---|---|---|
| 1 | 150 | 0.15 |
| 4 | 600 | 0.6 |
| 12 | 1800 | 1.8 |
| 24 | 3600 | 3.6 |
| 40 | 6000 | 6.0 |
| 60 | 9000 | 9.0 |
| 80 | 12000 | 12.0 |
When used with devices that have high throughput requirements like high resolution digital cameras, the high speed cards make a significant difference. Typically read speeds are even faster than the rated write speeds. Unless a very high performance factor is necessary, 40X cards currently provide the best performance to price ratio.
What is the difference between FAT-16 and FAT-32, why do cards greater than 2GB require FAT-32?
FAT (File Allocation Table) is the de-facto file system standard for all ATA style media. For many years FAT-16 which can address up to 2.14GB file systems was all that was ever necessary. However, as storage requirements have grown over the years and media with capacities greater than 2GB it became necessary to switch to FAT-32. Many digital cameras and other devices designed until recently don't support FAT-32. It is very important to check with the manufacturer of your devices before purchasing CompactFlash with capacities greater than 2GB. Hitachi's white paper covers this subject better than anything that we are aware of: An Introduction to FAT 16/FAT 32 File Systems
What it is Write Acceleration Technology?
WA is a Lexar technology that needs implementation in both the camera and the CF card. When both devices have WA it allows data transfers with less overhead, allowing better performance. Lexar Media's site provides much more in depth information on WA.
Write Acceleration and the Write Acceleration logo are trademarks of Lexar Media, Inc.
Is there a industry or standards body for CompactFlash?
Yes, the CompactFlash Association (CFA).
