Chapter 4 System Support
Compaq Deskpro EN Series of Personal Computers
Desktop and Minitower Form Factors
Third Edition - September 1998
4-44
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) Drive 66 (D) Drive 68 (E) Drive 15 (F) Function
B0h B5h BA h BFh No. of Cylinders, Low Byte
B1h B6h BB h C0h No. of Cylinders, High Byte
B2h B7h BCh C1h No. of Heads
B3h B8h BDh C2h Max ECC Bytes
B4h B9h BEh C3h No. of Sectors Per Track