🚀 go-pugleaf

To answer one of my own questions..

In article <1991Mar12.083348.8802@cm.cf.ac.uk> rhl@computing-maths.cardiff.ac.uk (Robert Hartill) writes:
>
> STUFF REMOVED..
>
>_Q2_:
>Is the timer interrupt, INT 8 disableable/enableable (sp?)
>'cos if i write an ISR to make use of it, it never gets *called*
>
>Under the Turbo Debugger with single stepping or breakpoints set, my ISR is
>called, I can only assume the TD simulates the timer interrupt.
>

I've now solved this problem for myself, thought i'd post what i'd found..

I put the following code in my program..
	mov	al,eeh
	mov	21h,al
this enables the 8253 timer chip, which *calls* INT 8, 19 or so times / sec
and enables the RS232 serial interface (which i want to use). It disables the
keyboard, disk interface, printer and colour/graphics (which i don't need)

At the end each interrupt (INT 8) i use the following code
	mov al,20h
	out 20h,al
this signals the end of an interrupt service routine (the one on INT 8)

I'm now able to context switch with my executive using INT 8,
Well i'm happy anyway.

I found this info in *Programming the 8086/8088* by Mike Thorne (p306)

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Do i need to thank myself for this help ?


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::     Robert Hartill, Dept Of Computing Mathematics, UWCC, Cardiff, UK.     ::
::          e-mail : rhl@cm.cf.ac.uk         Fax : 0222 371921               ::
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Give me the luxuries of life and I will willingly do without the necessities.
-Frank Lloyd Wright (1869-1959).
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