Commodore 1581 - Appendix C: DOS Diskette Format

APPENDIX C
DOS DISKETTE FORMAT
The DIRECTORY and BAM are located on logical track 40. The following is the
structure:
DIRECTORY HEADER (Track 40 sector 0)
BYTE
00-01
02
03
04-21
22-23
24
25
26
27-28
29-255
DEFINITION
Track and Sector of first DIRECTORY block.
Disk Version Number
$00
Disk Name*
Disk Id
SAO
DOS Version Number
Disk Version Number
AOh
$00
BAM for Logical Tracks 1-40 — BAM1 (Track 40 Sector 1)
BYTE
00-01
02
03
04-05
06
07
08-15
16-255
DEFINITION
Track and Sector of next BAM block
Version Number
Compliment Version Number
Disk Id
I/O-Byte (bit7-verify on/off, bit6-check header CRC on/off)
Auto Loader Flag*
Reserved for future use
BAM image for logical tracks 1-40 (6 bytes per track**)
*When the drive is reset it will hold off the serial bus and look for a file called
"COPYRIGHT CBM 86" of file type USSR. It will load and execute this file. The file must
have the following structure: The first two bytes of the file must contain the low and
high load addresses respectively. The third byte is the amount of characters to follow.
In addition a trailing checksum byte must be included. The load address is the
execution address. The BAM contains a flag byte which will allow auto execution with
an Initialize, Burst, Inquire, and Burst Query commands.
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