3. Theory of Operation
15
by the ZT 8952/8953. The ZT 8954 is not jumper selectable for any alternate I/O
address. The I/O map is shown below in the "
I/O Map
" figure.
†
3F7h is shared with the ZT 8952/53.
3F7h †
3F6h
3F5h
3F0h
Not Decoded
I/O Map
Floppy Disk Controller Registers
The Floppy Disk Controller (FDC) interface is composed of eight registers. The "
Floppy
Disk Controller I/O Registers
" table defines the I/O address for all of the FDC registers.
These registers are further described in Chapter 4, "
FDC Description (82078)
."
Floppy Disk Controller I/O Registers
I/O Port Address
I/O Read Function
I/O Write Function
3F0h
Status Register A
--
3F1h
Status Register B
Status Register B
3F2h
Digital Output Register
Digital Output Register
3F3h
Tape Drive Register
Tape Drive Register
3F4h
Main Status Register
Data Rate Select Register
3F5h
Data
Data
3F6h
Reserved
Reserved
3F7h
Digital Input Register
†
Configuration Control Register
†
Bit 7 only driven
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