ERROR - Error handling

Syntax:

CALL 400EH

or

JP 400EH

Input:

A = Error code (0 - 17)

Exit:

Jump to the BASIC interpreter

Registers used:

AF, BC. DE, HL

Error handling:

none

A powered-on drive is powered off. The drive motor stops and the LED on the front of the drive goes out.

An error message is output according to the error code transferred in the A register. A possibly switched on drive is switched off (with error code > 1).

This routine differs from the other routines insofar as it jumps to the BASIC interpreter instead of to the calling program.

The stack pointer is set to the BASIC stack.

Reg A	Generated message	Further process
0	none	to the BASIC interpreter (1B9AH)
1	?SYNTAX ERROR	Release and further expiry about 1997H
2	?FILE ALREADY EXISTS	to the BASIC interpreter (1B9AH)
3	?DIRECTORY FULL	to the BASIC interpreter (1B9AH)
4	?DISK WRITE PROTECTED	to the BASIC interpreter (1B9AH)
5	?FILE NOT OPEN	to the BASIC interpreter (1B9AH)
6	?DISK I/O ERROR	to the BASIC interpreter (1B9AH)
7	?DISK FULL	to the BASIC interpreter (1B9AH)
8	?FILE ALREADY OPEN	to the BASIC interpreter (1B9AH)
9	?SECTOR NOT FOUND	to the BASIC interpreter (1B9AH)
10	?CHECKSUM ERROR	to the BASIC interpreter (1B9AH)
11	?UNSUPPORTED DEVICE	to the BASIC interpreter (1B9AH)
12	?FILE TYPE MISMATCH	to the BASIC interpreter (1B9AH)
13	?FILE NOT FOUND	to the BASIC interpreter (1B9AH)
14	?DISK BUFFER FULL	to the BASIC interpreter (1B9AH)
15	?ILLEGAL READ	to the BASIC interpreter (1B9AH)
16	?ILLEGAL WRITE	to the BASIC interpreter (1B9AH)
17	?BREAK	to the BREAK routine (1DA0H) in BASIC

Example:

...
LD A,7          ; Error code 7
CALL 400EH      ; Output message "DISK FULL"

The message “?DISK FULL” is output and then BASIC responds with READY.

Note

Note:

Using the line number field in the BASIC communication area (78A2H), the ERROR routine distinguishes whether it is a direct command or a program command.

If field 78A2H/78A3H contains a value not equal to X’FFFF’, this is interpreted as a line number and this is output after the error message (error codes 1-16).

This function can perhaps also be useful when testing machine programs by setting specific values in 78A2H/78A3H which, if an error occurs, give you an indication of the corresponding point in the program.

Example:

...
OR A            ; check if error occurred
JR Z,XY         ; no, go on!
LD HL,10        ; set row identifier
JP 400EH        ; call error routine
XY: ...

If A contains a value not equal to 0, the corresponding error message is output with information about the location of the occurrence. e.g. A= 3, then “?DIRECTORY FULL IN 10”.