Supported Hardware

emFile's CompactFlash & IDE device driver can be used to access most ATA HD drives or CompactFlash storage cards also known as CF using true IDE or Memory card mode.

Theory of operation

CompactFlash

CompactFlash is a small, removable mass storage device. The CompactFlash Storage Card contains a single chip controller and flash memory module(s) in a matchbook-sized package with a 50-pin connector consisting of two rows of 25 female contacts each on 50 mil (1.27 mm) centers. The controller interfaces with a host system allowing data to be written to and read from the flash memory module(s).

There are two different Compact Flash Types, namely CF Type I and CF Type II. 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. 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. CF+ data storage cards are also available using magnetic disk (IBM Microdrive).

Modes of operation (interface modes)
Compact Flash cards can operate in three modes:

• Memory card mode
• I/O card mode
• True IDE mode

Supported modes of operation (interface modes)
Currently, TRUE IDE and MEMORY CARD mode are supported.

IDE (ATA) Drives

Just like CompactFlash cards, ATA drives have a built-in controller to drive and control the mechanical hardware in a drive. Actually there are two types of connecting ATA drives. 5.25 and 3.5 inch drives are using a 40 pin male interface to connect to an IDE controller. 2.5 and 1.8 inch drives, mostly used in Notebooks and embedded systems, have a 50 pin male interface.

Modes of operation (interface modes)
ATA drives can operate in a variety of different modes:

• PIO (Programmed I/O)
• Multiword DMA
• Ultra DMA

Supported modes of operation (interface modes)
Currently, only PIO mode through TRUE IDE is supported.

ATA drives: Hardware interfaces

Fail-safe operation

Unexpected Reset
The data will be preserved.

Power failure
Power failure can be critical: If the card does not have sufficient time to complete a write operation, data may be lost. Countermeasures: make sure the power supply for the card drops slowly.

Wear leveling

CompactFlash card are controlled by an internal controller, this controller also handles Wear leveling. Therefore, the driver does not need to handle wear leveling.