Commodore 2040 User Manual page 60

58
Table 12. 8050 BAM FORMAT
First BAM block: Track 38, Sector O.
BYTE CONTENTS DEFINITION
0,1 38,3 Track and sector of second BAM block.
2 67 ASCII character C indicating 8050 format.
3 0 Null flag for future DOS use.
4 1 Lowest track number represented in this BAM block.
5 51 Highest track number +1 in this BAM block.
6
Number of blocks unused on track l.
7-10 Bit map representation of available blocks on track l.
11-255 *BAM for tracks 2-50, 5 bytes per track.
Second BAM block: Track 38, Sector 3.
BYTE CONTENTS DEFINITION
0,1 39,1 Track and sector of first directory block.
2 67
ASCII character C indicating 8050 format.
3 0 Null flag for future DOS use.
4
1 Lowest track number represented this BAM block.
5 51 Highest track number +1 in this BAM block.
6
Number of blocks unused on track 5l.
7-10
Bit map representation of available blocks on track 51.
11-140
*BAM for tracks 52-77, 5 bytes per track.
141-255
Unused.
*STRUCTURE OF BAM ENTRY FOR A TRACK
BYTE
DEFINITION
0
number of available sectors for track
1 bit map sectors 0-7
2 bit map sectors 8-15
1=available
3 bit map sectors 16-23
O=not available
4 bit map sectors 24-31
Note: "BLOCKS FREE" may appear in locations 180 thru 191 on some diskettes.