Compaq EN Series Technical Reference Manual page 93

Chapter 4 System Support
Configuration Byte 9Dh, ESS Audio Configuration Byte
Default Value = 12h
Bit Function
7 Reserved for Game Port Enable
6,5 Audio Address
00 = 22xh
01 = 23xh
10 = 24xh
11 = 25xh
4,3 DMA Channel
00 = Disabled
01 = DMA0
10 = DMA1
11 = DMA3
2,1 IRQ Select
00 = IRQ9
01 = IRQ5
10 = IRQ7
11 = IRQ10
0 ESS Audio Chip Enable
0 = Enabled
1 = Disabled
Configuration Byte 9Eh, ECP DMA Configuration Byte
Default Value = 03h
Bit Function
7..4 Reserved
3 SafeStart Control:
0 = Disable
1 = Enable
2..0 ECP DMA Channel
000 = Invalid
100 = Disabled
All other values (001-011, 101-111) refer to channel no.
Configuration Byte 9Fh-AFh, Asset Tag Serial Number
Configuration Bytes B0h-C3h; Custom Hard Drive Information
These bytes contain the number of cylinders, heads, and sectors per track for hard drives C, D, E,
and F respectively. The mapping for each drive is as follows:
Drive 65 (C)
B0h
B1h
B2h
B3h
B4h
4-44 Compaq Deskpro EN Series of Personal Computers
Desktop and Minitower Form Factors
Drive 66 (D) Drive 68 (E)
B5h BAh
B6h BBh
B7h BCh
B8h BDh
B9h BEh
Third Edition - September 1998
Drive 15 (F) Function
BFh No. of Cylinders, Low Byte
C0h No. of Cylinders, High Byte
C1h No. of Heads
C2h Max ECC Bytes
C3h No. of Sectors Per Track