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All DOS ROMs

Address Label Description
6069-606A DEVDESP Pointer: Internal device descriptor (drive) table in PROM
606B-606C DEVDES Pointer: Internal device descriptor (drive) table in RAM

ABC 6-2x and ABC 6-3x drive table
Drive Offset Default Description
00 08/10 DR0 offset
SF 01 2C Card select address
02 04 Cluster size
MF 03 2D Card select address
04 04 Cluster size
HD 05 24 Card select address (not accessable)
06 20 Cluster size
unused07 25 Card select address
08 01 Cluster size

UFD-DOS drive table.
Table is variable lenght and it ends when drive name is 0000h.
Offset Description
Header 00 DR redirection offset
01 (unused)
02-03 DR drive name
First drive 04 Card type and select address
05 Cluster size and addressing type
06-07 Name
Second drive 08 Card type and select address
09 Cluster size and addressing type
0A-0B Name
And so on.. ...
Last drive XX+00 Card type and select address
XX+01 Cluster size and addressing type
XX+02 Name
Terminator XX+04 Undefined
XX+05 Undefined
XX+06 Zero (name)

Card select address is coded as follows
Bit # Description
07-06 Controller type:
00 W5/W8 Winchester
01 A6/A8 ABC 832, ABC 834, ABC 838 or DD88
10 A5 ABC 830
11 A6/A8 fast
05-00 Card select address (0-63)

Cluster size is coded as follows
Bit # Description
06 Addressing type:
0Linear
1Biased
05-03 Reserved
02-00 Cluster size:
000 1
001 2
010 4
011 8
100 16
101 32
110 64
111128

UFD-DOS and WINCHESTER ROMs

Address Label Description
606D-606E UFDENT Pointer: UFD-entry for disk
606F DOSVER DOS version number
6070 DOSTYPE DOS type
ValueDescription
00 UFD-DOS ABC 80x
01 UFD-DOS ABC 80
02 RAM-OS
03 ABC-Net Central
04 ABC-Net Terminal (ABC 80x)
05 ABC-Net Terminal (ABC 80)
06 UFD-DOS Net
6071-6072 DRWRET Pointer: Return pointer for read/write routine
6073-6074 CSS Pointer: Clustersize
6075-6076 CHANN Pointer: Actual card select byte

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This page has been created by Sami Rautiainen.
Read the small print. Last updated June 15, 2000.