General frequently asked questions about CompactFlash
1. Are Hitachi and IBM 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.
2. Is there a industry or standards body for CompactFlash?
Yes, the CompactFlash Association (CFA).
3. 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.
CompactFlash Speeds |
Speed |
KBytes/sec |
MBytes/sec |
1X |
150 |
0.15 |
4X |
600 |
0.6 |
12X |
1800 |
1.8 |
24X |
3600 |
3.6 |
40X |
6000 |
6.0 |
45X |
6750 |
6.75 |
60X |
9000 |
9.0 |
80X |
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, 45X cards currently provide the best performance to price ratio.
4. What are the characteristics of CF cards?
Capacities?
- CF cards are available in capacities from 16MB to 12GB. The CF Specification can support capacities up to 137GB.
- While many CF applications can operate with low capacity CF cards, higher capacity cards are increasingly used as digital camera resolution rises.
Dual Voltage Support?
- CompactFlash cards support both 3.3V and 5V operation and can be interchanged between 3.3V and 5V systems. This means that any CF card can operate at either voltage. Other small form factor flash cards may be available to operate at 3.3V or 5V, but any single card can operate at only one of the voltages
The Connector?
- The connector used with CompactFlash is similar to the PCMCIA Card connector, but with 50 pins. Years of field experience in portable devices have proven the reliability and durability of this connector in applications where frequent insertions/ejections of the card are required. Other small form factor flash cards use connector technology that is not reliable or durable.
Cost?
- CompactFlash provides the lowest cost flash storage solution. With the built-in controller, a wide variety of low cost flash technologies can be used. The built-in controller lowers costs further by allowing defective cells to be mapped out, thus increasing flash chip yields and by reducing costs in the host device.
Temperature?
- CompactFlash cards are able to withstand extremely rapid increases or decreases in temperature. Industrial version CompactFlash cards are offered with an extended operating temperature range of -40 C to +85 C.
Shock?
- CompactFlash cards have an operating shock rating of 2,000 Gs, which is equivalent to a 10-foot drop. With typical usage, a CompactFlash card can be used for more than 100 years with no loss or deterioration of data.
Power?
- Typically consuming less than five percent of the power than that required to operate 1.8" and 2.5" disk drives, CF cards run at 3.3V or 5V with a single power supply. This makes them ideal for a range of current and next-generation, small-form factor consumer applications.
Operating System Support?
- Numerous platforms and operation systems support CompactFlash and the PCMCIA-ATA standard, including DOS, Windows 3.x, Windows 95, , Windows 98, Windows CE, Windows 2000, Windows ME, Windows XP, OS/2, Apple System 7, 8, 9 & OS X, Linux and most types of UNIX.
Data Reliability?
- CompactFlash data is protected by built-in dynamic defect management and error correction technologies.
5. 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.
6. What is CompactFlash, CF Type I and CF Type II?
CompactFlashR is a small, removable mass storage device. First introduced in 1994, CompactFlash cards weigh a half ounce and are the size of a matchbook. They provide complete PCMCIA-ATA functionality and compatibility.
At 43mm (1.7") x 36mm (1.4") x 3.3mm (0.13"), the CF Type I card's thickness is less than one-half of a current PCMCIA Type II card. It is actually one-fourth the volume of a PCMCIA card. Compared to a 68-pin PCMCIA card, a CF card has 50 pins but still conforms to ATA specs. 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.
At 43mm (1.7") x 36mm (1.4") x 5mm (0.19"), the CF Type II card's thickness is equal to a current PCMCIA Type II card. It is actually less than one-half the volume of a PCMCIA card. Compared to a 68-pin PCMCIA card, a CF card has 50 pins but still conforms to ATA specs. It can be easily slipped into a passive 68-pin PCMCIA Type II to CF Type II adapter that fully meets PCMCIA electrical and mechanical interface specifications.
The only difference between CF Type I and CF Type II cards is the card thickness . CF Type I is 3.3 mm thick and CF Type II cards are 5mm thick. A CF Type I card will operate in a CF Type I or CF Type II slot. A CF Type II card will only fit in a CF Type II slot. The electrical interfaces are identical. CompactFlash is available in both CF Type I and CF Type II cards, though predominantly in CF Type I cards. The Microdrive is a CF Type II card. Most CF I/O cards are CF Type I, but there are some CF Type II I/O cards.
CompactFlash cards are designed with flash technology, a nonvolatile storage solution that does not require a battery to retain data indefinitely.
The CompactFlash card specification version 2.0 supports data rates up to 16MB/sec and capacities up to 137GB.
CompactFlash storage products are solid state, meaning they contain no moving parts, and provide users with much greater protection of their data than conventional magnetic disk drives. They are five to ten times more rugged and reliable than disk drives including those found in PC Card Type III products. CF cards consume only five percent of the power required by small disk drives.
CompactFlash cards support both 3.3V and 5V operation and can be interchanged between 3.3V and 5V systems. This means that any CF card can operate at either voltage. Other small form factor flash cards may be available to operate at 3.3V or 5V, but any single card can operate at only one of the voltages.
CompactFlash provides the lowest cost flash storage solution. With the built-in controller, a wide variety of low cost flash technologies can be used. The built-in controller lowers costs further by reducing costs in the host device and allowing defective flash chip cells to be mapped out, thus increasing flash chip yields. CompactFlash provides the lowest cost data storage solution.
When compatibility, interoperability, reliability, cost, and performance count, CF and CompactFlash cards are the ATA-compatible solution that delivers.
7. 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 |
8. 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.
9. Where is CompactFlash used?
Many leading consumer electronics companies have designed CF technology into next-generation products developed for consumer markets. CF technology is widely used in such products as portable and desktop computers, digital cameras, handheld data collection scanners, PDAs, Pocket PCs, handy terminals, personal communicators, advanced two-way pagers, audio recorders, monitoring devices and set-top boxes. CF technology offers all of these applications new and expanded functionality while enabling smaller and lighter designs.
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