block.asm:; 1234H and 4321H on the top and bottom.  These are used in debugging to
block.asm:                dw      4321H           ; End of stack always 4321H
core.asm:crctab  DW 00000H, 01021H, 02042H, 03063H, 04084H, 050a5H, 060c6H, 070e7H
core.asm:                int     21H
drmain.asm:                int     21H
drmain.asm:                int     21H
drmain.asm:                int     21H
drmain.asm:                int     21H
drmain.asm:                int     21H
init.asm:                int     21H
init.asm:                int     21H             ; Return allocated block in UMB
init.asm:                int     21H
init.asm:                int     21H
init.asm:                int     21H
init.asm:                int     21H
init.asm:                int     21H
init.asm:                int     21H
init.asm:                int     21H
init.asm:                int     21H
init.asm:                int     21H
init.asm:                int     21H
init.asm:                int     21H
init.asm:                int     21H
init.asm:                int     21H
init.asm:                int     21H
init.asm:                int     21H
init.asm:                int     21H
parallel.asm:                int     21H             ; Current timer vector -> par_timer_save
parallel.asm:                int     21H             ; Set timer vector to timer handler
parallel.asm:                int     21H
printer.asm:                int     21H
printer.asm:                int     21H
serial.asm:PICSTAT2        EQU     21H
serial.asm:mask_ints:      in      al, 21H         ; Get current interrupt mask
serial.asm:                out     21H, al
serial.asm:                out     21H, al
serial.asm:                int     21H             ; Current timer vector -> timer_save
serial.asm:                int     21H             ; Set timer vector to timer handler
serial.asm:                int     21H
