INT 23 - DOS 1+ - CONTROL-C/CONTROL-BREAK HANDLER
---DOS 1.x---
Return: AH = 00h abort program
if all registers preserved, restart DOS call
---DOS 2+---
CF clear
Return: all registers preserved
return via RETF or RETF 2 with CF set
DOS will abort program with errorlevel 0
else (RETF/RETF 2 with CF clear or IRET)
interrupted DOS call is restarted
Notes:  this interrupt is invoked whenever DOS detects a ^C or ^Break; it
should never be called directly
MSDOS 1.25 also invokes INT 23 on a divide overflow (INT 00)
DOS remembers the stack pointer before calling INT 23, and if it is
not the same on return, pops and discards the top word; this is what
permits a return with RETF as well as IRET or RETF 2
any DOS call may safely be made within the INT 23 handler, although
the handler must to check for a recursive invocation if it does
call DOS

See also: 1B

23 - DOS 1+ - CONTROL-C/CONTROL-BREAK HANDLER