Format; I O Channels - Commodore 2031 User Manual

DATA BLOCK
Byte
0,1
2-255
SIDE SECTOR BLOCK
Byte
0,1
2
3
4,5
6,7
8,9
10,11
12,13
14,15
16-255
I/O CHANNELS
When a channel is opened to a previously existing file, the DOS will position to
the first record provided that the given parameters match properly. The record
length variable is not necessary on the OPEN if the file is already in existence,
but the DOS causes a check to be made against the record size that was origi-
nally made in the DOPEN statement creating the file. If these do not match,
then error 50 -record not present- will be generated.
62
Table 11
Definition
Track and sector of next data block.
254 bytes of data. Empty records contain FF (all binary
ones) in the first byte followed by 00 (binary all zeros) to
the end of the record. Partially filled records are padded
with nulls (00).
Definition
Track and sector of next side sector block.
Side sector number. (0-5)
Record length.
Track and sector of first side sector (number 0)
Track and sector of second side sector (number 1)
Track and sector of third side sector (number 2)
Track and sector of fourth side sector (number 3)
Track and sector of fifth side sector (number 4)
Track and sector of sixth side sector (number 5)
Track and sector pointers to 120 data blocks.
RELATIVE FILE FORMAT