Commodore Computers 1581 - Disk Format Organization; Memory Map and Locations; I;O Address Map

1581 SERVICE MANUAL
STORAGE:
SPECIFICATIONS (continued)
12 Bytes of 00
3 Bytes of Hex A1 (Data Hex A1, Clock Hex 0A)
1 Byte of Hex FB (Data Address Mark)
512 Bytes of Data
2 Bytes of CRC (Cyclic Redundancy Check)
38 Bytes of Hex 4E
FORMAT ORGANIZATION
PHYSICAL:
Cylinders 0 thru 79
Sectors 1 thru 10 on Side 1
Sectors 1 thru 10 on Side 2
Sector Size 512
LOGICAL:
Tracks 1 thru 80
Sectors 0 thru 39 (Using physical Sectors 1 ...10 — Side 1 and 2)
Sector Size 256 Bytes
Total Unformatted Capacity 1 Megabyte
Total Formatted Capacity 808, 960 Bytes
Maximum Sequential File Size 802, 640 Bytes
Maximum Relative File Size 182, 880 Bytes
Records Per File 65, 535
Files Per Diskette *296
Cylinders Per Diskette 80
Logical Sectors Per Cylinder 40
Physical Sectors Per Cylinder 20
Logical Bytes Per Sector 256
Physical Bytes Per Sector 512
Free Blocks Per Disk 3160
*More with Sub-Disk Partitioning
MEMORY MAP — I/O LOCATIONS
8Kx8 RAM $0002-$1FFF
8520A $4000-$4010 Controller, Serial Bus
WD 1770 $6000-$6003 MFM Disk Controller
32K x 8 ROM $8000-$FFFF DOS, Controller Code