Disc Organisation; Common To All Formats; System Format - AMSTRAD cpc 6128 User Instruction

Note that when key values for the SECOND joystick are returned, the computer
cannot tell whether those values have been generated by the joystick or by the
equivalent keyboard key (indicated in the last column of the previous table). This
means that the keyboard can be used as a substitute for the second joystick.
Part 12: Disc organisation
The BIOS supports three different disc formats: SYSTEM format, DATA ONLY
format and IBM format. Under AMSDOS, the format of a disc is automatically
detected each time a disc with no open files is accessed. To permit this automatic
detection, each format has unique sector numbers.
3 inch discs are double sided, but only one side may be accessed at a time depending on
which way round the user inserts the disc. There may be a different format on each
side.
Common to all formats:
Single sided (the two sides of a 3 inch disc are treated separately).
512 byte physical sector size.
40 tracks numbered 0 to 39.
1024 byte
CP/M
block size.
64 directory entries.
SYSTEM format
9 sectors per track numbered &41 to &49.
2 reserved tracks.
The system format is the main format supported, since
CP/M
can only be loaded from
a system format disc.
CPIM
2.2 also requires a system format disc to be inserted for a
warm boot. The reserved tracks are used as follows:
Track 0 sector &41
Track 0 sector &42
Track 0 sectors &43 to &47
Track 0 sectors &48 to &49
Track 1 sectors &41 to &49
CP/M2.2
CP/MPlus
: boot sector for
CP!M
2.2 : boot sector for CP
IM
PI us
: configuration sector
: unused
~
} CCP and BD OS
} unused
Note that VENDOR format is a special version of system format which does not
contain any system software on the two reserved tracks. It is intended for use in
software distribution.
Chapter 7 Page 44 For your reference ....