W83977A Winbond Electronics Corp America, W83977A Datasheet - Page 41

• Manufacturer Part Number: W83977A
• Description: Winbond I/O
• Manufacturer: Winbond Electronics Corp America

2.2.3 Digital Output Register (DO Register) (Write base address + 2)
The Digital Output Register is a write-only register controlling drive motors, drive selection, DRQ/IRQ
enable, and FDC resetting. All the bits in this register are cleared by the MR pin. The bit definitions are
as follows:
2.2.4 Tape Drive Register (TD Register) (Read base address + 3)
This register is used to assign a particular drive number to the tape drive support mode of the data
separator. This register also holds the media ID, drive type, and floppy boot drive information of the
floppy disk drive. In normal floppy mode, this register includes only bit 0 and 1. The bit definitions are as
follows:
If three mode FDD function is enabled (EN3MODE = 1 in
are as follows:
7
6
5
7
4
6
X
7
3
X
5
6
5
X
2
4
X
4
3
1-0
X
3
2
-33 -
Drive Select: 00 select drive A
Floppy Disk Controller Reset
Active low resets FDC
DMA and INT Enable
Active high enable DRQ/IRQ
Motor Enable A. Motor A on when active high
Motor Enable B. Motor B on when active high
Motor Enable C. Motor C on when active high
Motor Enable D. Motor D on when active high
X
2
1
1
Logical Device 0 CRF0
0
0
Tape Sel 0
Tape Sel 1
Floppy boot drive 0
Floppy boot drive 1
Drive type ID0
Drive type ID1
Media ID0
Media ID1
10 select drive C
11 select drive D
01 select drive B
Tape sel 1
Tape sel 0
Publication Release Date: April 1998
W83977TF
bit:0), the bit definitions
PRELIMINARY
Revision 0.62