Re: A86: Terms

To: assembly-86@lists.ticalc.org
Subject: Re: A86: Terms
From: Stephen Hicks <shicks@mindspring.com>
Date: Tue, 05 May 1998 17:17:05 -0400
Delivered-To: assembly-86-outgoing@towerguard.unix.edu.sollentuna.se
References: <3.0.5.32.19980505153640.007a4820@tfs.net>
Reply-To: assembly-86@lists.ticalc.org


Because this is a calculator, not a PC...  We're lucky enough to even be able to
use any user interrupt (even though IM 2 would be there even if ti didn't care
about us... :-)
I suppose you could write an interrupt routine in the user interrupt area that
would look at some freaky vectors somewhere and use them, but as it is coded in
the ram, it just checks if there's a user interrupt installed and if so, jumps to
it.

David Phillips wrote:

> Why can't there be more than one user interrupt installed at a time?  On
> the pc when you install an interrupt, you just read in the vector of the
> int you want, set it to the start of your ISR (interrupt service routine),
> then call the old ISR at the end of yours.   So if program A is running
> when you install your program B, program B reads in A's address, sets the
> vector (the address the cpu calls when that interrupt is run) to it's
> address (program B's address), then calls program A's address when it's done.
>
> At 10:48 AM 5/5/98 -0500, you wrote:
> >
> >hooking into refers to anything that changes the normal operation of the
> >system. so the user fonts, the interupts, the tokenizing are all hooks. tsr
> >are user defined interupts (i suppose you could call the other interupts
> >tsr's too). the font is just a table that bypasses the other font table if
> >the flag is set to look up the font in your table first before it looks it
> >up in the regular font table. the addons you are talking about (you mean
> >special functions,etc?) are installed into memory but can be overwritten
> >easily if another program thats installing doesnt check them. only one user
> >defined interupt can be there at one time (that is unless someone makes a
> >program that checks the user defined interupt, turns the flag off that makes
> >the interupt work, then puts their interupt into the memory starting right
> >on the ret of the other interupt...then you could have more than one
> >interupt installed but they might conflict).
>
> ----------------
> David Phillips
> electrum@tfs.net



--
Stephen Hicks
mailto:shicks@mindspring.com
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IRC/AIM:Kupopo
Hopemage:http://www.mindspring.com/~shicks/

References:

Re: A86: Terms

From: David Phillips <electrum@tfs.net>