stevens@vms.macc.wisc.edu (PAul STevens -- MACC) (06/05/91)
I have a more-or-less realtime application that will just barely keep
up with the world on a Convertible. But I have what seems to be a
problem with the keyboard interrupt. I replace the keyboard interrupt
vector (at address 00:24h) and receive interrupts very nicely. But
it appears that the interrupt itself requires about one millisecond!
At the interrupt address:
push ax
in al,21h
or al,2 ; disable keyboard
out 21h,al
mov al,20h
out 20h,al ; reenable interrupt chip
sti
nop
It seems that it takes about one millisecond to get to the nop when a
keyboard interupt occurs. What is going on?????? Is the keyboard actually
causing some other interrupt which is then passed on to me
after some thrashing about? I cannot afford to spend one millisecond with
interrupts locked out.