Subversion Repositories SvarDOS

Rev

Rev 967 | Show entire file | Ignore whitespace | Details | Blame | Last modification | View Log | RSS feed

Rev 967 Rev 1836
Line 5... Line 5...
5 
; Copyright (C) 2022 Mateusz Viste
 5 
; Copyright (C) 2022 Mateusz Viste
6 
;
 6 
;
7 
; this is an executable image that can be set up as the critical error handler
 7 
; this is an executable image that can be set up as the critical error handler
8 
; interrupt (int 24h). It displays the usual "Abort, retry, fail" prompt.
 8 
; interrupt (int 24h). It displays the usual "Abort, retry, fail" prompt.
9 
;
 9 
;
- 
 
 10 
; documentation:
- 
 
 11 
; http://www.techhelpmanual.com/564-int_24h__critical_error_handler.html
- 
 
 12 
;
10 
 
 13 
 
11 
org 0   ; this code does not have a PSP, it is loaded as-is into a memory
 14 
org 0   ; this code does not have a PSP, it is loaded as-is into a memory
12 
        ; segment
 15 
        ; segment
13 
 
 16 
 
14 
; === CRIT HANDLER DETAILS ====================================================
 17 
; === CRIT HANDLER DETAILS ====================================================
Line 47... Line 50...
47 
;   AL=3  return to application indicating a failure of the DOS function
 50 
;   AL=3  return to application indicating a failure of the DOS function
48 
;
 51 
;
49 
; A very basic "always fail" handler would be as simple as this:
 52 
; A very basic "always fail" handler would be as simple as this:
50 
;   mov al, 3
 53 
;   mov al, 3
51 
;   iret
 54 
;   iret
- 
 
 55 
;
- 
 
 56 
;
- 
 
 57 
; *** DOS CALLS ***
- 
 
 58 
;
- 
 
 59 
; Warning! Be careful about using DOS fns in your Critical Error handler.
- 
 
 60 
;          With DOS 5.0+, ONLY the following fns can be called safely:
- 
 
 61 
;
- 
 
 62 
;          01H-0CH (DOS character I/O)
- 
 
 63 
;          33H (all subfns are OK, including 3306H get DOS version)
- 
 
 64 
;          50H (set PSP address)
- 
 
 65 
;          51H and 62H (query PSP address)
- 
 
 66 
;          59H (get extended error information)
52 
; =============================================================================
 67 
; =============================================================================
53 
 
 68 
 
54 
 
 69 
 
55 
; save registers so I can restore them later
 70 
; save registers so I can restore them later
56 
push ah
 71 
push ah