w83977eg Winbond Electronics Corp America, w83977eg Datasheet - Page 34

• Manufacturer Part Number: w83977eg
• Description: Winbond Isa I/o W83977ef W83977eg
• Manufacturer: Winbond Electronics Corp America

(20) Invalid
5.2
There are several status, data, and control registers in W83977EF. These registers are defined below:
5.2.1
This register is used to monitor several disk interface pins in PS/2 and Model 30 modes. In PS/2 mode,
the bit definitions for this register are as follows:
INIT PENDING (Bit 7):
This bit indicates the value of the floppy disk interrupt output.
DRV2# (Bit 6):
0
1
STEP (Bit 5):
This bit indicates the complement of STEP# output.
Command
Result
PHASE
Register Descriptions
A second drive has been installed
A second drive has not been installed
base address + 0
base address + 1
base address + 2
base address + 3
base address + 4
base address + 5
base address + 7
Status Register A (SA Register) (Read base address + 0)
ADDRESS
OFFSET
R/W
W
R
D7
7
------------- Invalid Codes -----------------
-------------------- ST0 ----------------------
D6
6
5
D5
DT (FIFO) REGISTER
4
SB REGISTER
MS REGISTER
SA REGISTER
TD REGISTER
DI REGISTER
D4
W83977EF-AW/W83977EG-AW
3
READ
D3
-32-
2
1
D2
0
D1
REGISTER
DIR
INDEX#
WP#
HEAD
TRAK0#
STEP
INIT PENDING
DRV2#
D0
Invalid codes (no operation-
FDC goes to standby state)
ST0 = 80H
DT (FIFO) REGISTER
DO REGISTER
DR REGISTER
CC REGISTER
TD REGISTER
WRITE
REMARKS