FILE TYPES
Program (PRG)
This type contains data encoded in CBM BASIC format. Files of this type may
be read into the CBM computer with the LOAD command and written to the
disk with either the SAVE command or with the “S” command (from the
editor).
Sequential (SEQ) or User (USR)
This type contains data encoded in any manner. Sequential files are used by the
CBM editor and are also used by various custom programs written by users.
Relative (REL)
This type contains data encoded in any manner. Associated with the relative file
will also be side sectors which hold pointers to data within the relative file.
(Refer to Chapter 6 for further description).
Block, Directory and BAM Formats
A data block is addressed by track and sector. A 2031 diskette contains 35 tracks
(or rings) numbered 1 to 35. The number of sectors per track will vary (as
illustrated in Table 4) due to differences in track circumference and recording
frequency.
The 2031 maintains a system file on track 18 which contains the BAM, diskette
name, ID and file directory. The BAM, resident in the first 128 bytes of sector 0,
monitors available and occupied storage locations on the diskette. The last 128
bytes of sector 0 are used to store the diskette name and ID. The file directory
begins on the next sector, sector 1.
49
To Next Page
Loading...
