w83877atd Winbond Electronics Corp America, w83877atd Datasheet - Page 32

• Manufacturer Part Number: w83877atd
• Description: Winbond I/o
• Manufacturer: Winbond Electronics Corp America

2.2 Register Descriptions
There are several status, data, and control registers in W83877ATF. These registers are defined
below:
2.2.1 Status Register A (SA Register) (Read base address + 0)
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.
0
1
STEP (Bit 5):
This bit indicates the complement of STEP output.
This bit indicates the value of TRAK0 input.
HEAD (Bit 3):
This bit indicates the complement of HEAD output.
0
1
DRV2 (Bit 6):
TRAK0 (Bit 4):
A second drive has been installed
A second drive has not been installed
side 0
side 1
base address + 0
base address + 1
base address + 2
base address + 3
base address + 4
base address + 5
base address + 7
ADDRESS
OFFSET
7
6
5
DT (FIFO) REGISTER
4
SB REGISTER
MS REGISTER
SA REGISTER
TD REGISTER
DI REGISTER
3
READ
2
- 28 -
1
0
REGISTER
DIR
WP
INDEX
HEAD
TRAK0
STEP
INIT PENDING
DRV2
Publication Release Date: April 1998
DT (FIFO) REGISTER
DO REGISTER
DR REGISTER
CC REGISTER
TD REGISTER
W83877ATF
WRITE
Version 0.51