Technical Reference Guide
Compaq Deskpro 4000N and 4000S Personal Computers
First Edition - September 1997
5-7
Drive Control Register, I/O Port 3F6h/376h (Write Only)
Bit Function
7..3 Reserved
2 Controller Control:
0 = Re-enable
1 = Reset
1 Interrupt Enable/Disable
0 = Disable interrupts
1 = Enable interrupts
0 Reserved
Drive Access Register, I/O Port 3F7h/377h (Read Only)
Bit Function
7 Reserved
6 WRITE GATE- Signal Active (if set)
5..2 Head Select:
0000 = 15 1000 = 7
0001 = 14 1001 = 6
0010 = 13 1010 = 5
0011 = 12 1011 = 4
0100 = 11 1100 = 3
0101 = 10 1101 = 2
0110 = 9 1110 = 1
0111 = 8 1111 = 0
1,0 Drive Select:
00 = Disabled
01 = Drive 1 selected
10 = Drive 0 selected
11 = Invalid
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