Code | Extension |
---|---|
0 | BIN |
1 | TXT |
2 | CMD |
3 | BAS |
4 | SYS |
5 | BAK |
6 | SCR |
7 | DAT |
8 | BAC |
9 | DIR |
10 | PRT |
11 | OUT |
Any values other than those above are ignored, the routine returning without
storing any extensions.
DISK ERROR #nnn
Where "nnn" is the error number being reported. A description of the error
numbers is given in FLEX Error Messages.
On entry, the X-register contains the address of a single binary byte. The
byte ot which the X-register points is printed as 2 hexadecimal digits.
The entire table is ended by a zero byte. For example, the following table
contains the commands DEBUG (entry at $3000) and PUNT (entry at $3200):
The address of the User Command Table is made known to DOS by storing it in the
User Command Table Address locations (see).
The User Command Table is searched before the disk directory, but after DOS's
own command table is searched. The DOS command table contains only the GET and
MON commands. Therfore, the user may not define his own GET and MON commands.
Since the User Command Table is searched before the disk directory, the
programmer may have commands with the same name as those on the disk. However,
in this case, the commands on the disk will never be executed while the User
Command Table is known to DOS. The User Command Table may be deactivated by
clearing the User Command Table Address locations.
Disk commands, when loaded into memory, may reside anywhere in the User RAM
Area; the address is determined at assembly time by using an ORG statement.
Most commands may be assembled to run in the
Utility Command Space.
Most of the commands supplied with FLEX run in the Utility Command Space.
For this reason, the
SAVE command
cannot be used to save information which is
in the Utility Command Space or System FCB space as this information would be
destroyed when the
SAVE command
command is loaded. The
SAVE.LOW command
command is to be used
in this case. The
SAVE.LOW command
command loads into memory at location $100 and
allows the saving of programs in the $C100 region.
The System FCB area is used to load all commands from the disk. Commands
written to run in the Utility Command Space must not overflow into the
System FCB area. Once loaded, the command itself may use the System FCB
area for scratch or as an FCB for its own disk I/O. Look for an example in
FLEX File Management System.
FCC 'command' (Name that will invode the program)
FCB 0
FDB entry address (The entry address of the program)
FCC 'DEBUG' FCB 0 FDB $3000 FCC 'PUNT' FCB 0 FDB $3200 FCB 0 End of Command table DISK-RESIDENT COMMANDS:
A disk-resident command is an assembled program, with a transfer address, which
has been saved on the disk with a CMD extension.
SEE ALSO