Compaq Deskpro EP 6233 Technical Reference Manual page 110

Chapter 5 Input/Output Interfaces
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
0001 = 14
0010 = 13
0011 = 12
0100 = 11
0101 = 10
0110 = 9
0111 = 8
1,0 Drive Select:
00 = Disabled
01 = Drive 1 selected
10 = Drive 0 selected
11 = Invalid
5-8 Compaq Deskpro EP Series of Personal Computers
1000 = 7
1001 = 6
1010 = 5
1011 = 4
1100 = 3
1101 = 2
1110 = 1
1111 = 0
First Edition – April 1998