w83977eg Winbond Electronics Corp America, w83977eg Datasheet - Page 38

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

5.2.3
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:
5.2.4
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 CR9), the bit definitions are as follows:
Media ID1 Media ID0 (Bit 7, 6):
These two bits are read only. These two bits reflect the value of CR8 bit 3, 2.
Drive type ID1 Drive type ID0 (Bit 5, 4):
These two bits reflect two of the bits of CR7. Which two bits are reflected depends on the last drive
selected in the DO REGISTER.
Digital Output Register (DO Register) (Write base address + 2)
Tape Drive Register (TD Register) (Read base address + 3)
7
6
5
7
4
6
X
7
3
X
5
6
5
X
2
4
X
4
3
1-0
W83977EF-AW/W83977EG-AW
X
3
2
-36-
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
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
01 select drive B
10 select drive C
11 select drive D
Tape sel 1
Tape sel 0