TS2G~8GCF266 | 266X CompactFlash Card |
¾Card (Drive) Address Register (Address 3F7h[377h]; Offset Fh)
This register is provided for compatibility with the AT disk drive interface. It is recommended that this register not be mapped into the host’s I/O space because of potential conflicts on Bit 7.
Bit 7: this bit is unknown.
Implementation Note:
Conflicts may occur on the host data bus when this bit is provided by a Floppy Disk Controller operating at the same addresses as the CompactFlash Storage Card. Following are some possible solutions to this problem for the PCMCIA implementation:
1)Locate the CompactFlash Storage Card at a non-conflicting address, i.e. Secondary address (377) or in an independently decoded Address Space when a Floppy Disk Controller is located at the Primary addresses.
2)Do not install a Floppy and a CompactFlash Storage Card in the system at the same time.
3)Implement a socket adapter that can be programmed to (conditionally) tri-state D7 of I/0 address 3F7h/377h when a CompactFlash Storage Card is installed and conversely to tristate D6-D0 of I/O address 3F7h/377h when a floppy controller is installed.
4)Do not use the CompactFlash Storage Card’s Drive Address register. This may be accomplished by either a) If possible, program the host adapter to enable only I/O addresses 1F0h-1F7h, 3F6h (or 170h-177h, 176h) to the CompactFlash Storage Card or b) if provided use an additional Primary / Secondary configuration in the CompactFlash Storage Card which does not respond to accesses to I/O locations 3F7h and 377h. With either of these implementations, the host software shall not attempt to use information in the Drive Address Register.
Bit 6 (-WTG): this bit is 0 when a write operation is in progress; otherwise, it is 1.
Bit 5 (-HS3): this bit is the negation of bit 3 in the Drive/Head register.
Bit 4 (-HS2): this bit is the negation of bit 2 in the Drive/Head register.
Bit 3 (-HS1): this bit is the negation of bit 1 in the Drive/Head register.
Bit 2 (-HS0): this bit is the negation of bit 0 in the Drive/Head register.
Bit 1 (-nDS1): this bit is 0 when drive 1 is active and selected.
Bit 0 (-nDS0): this bit is 0 when the drive 0 is active and selected.
Transcend Information Inc. | 51 |
