Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!ames!ncar!oddjob!uwvax!geowhiz!scott
From: scott@geowhiz.UUCP (Scott Kempf)
Newsgroups: comp.sys.apple
Subject: Re: 60 Hz interrupt mod
Message-ID: <770@geowhiz.UUCP>
Date: 22 Apr 88 20:12:48 GMT
References: <8804211832.aa02388@SMOKE.BRL.ARPA>
Reply-To: scott@geowhiz.UUCP (Scott Kempf)
Organization: University of Wisconsin, Department of Geology and Geophysics
Lines: 28

In article <8804211832.aa02388@SMOKE.BRL.ARPA> PGOETZ@LOYVAX.BITNET writes:
>
>   Derived from "A Clock Interrupt for Your Apple" by Charles Putney,
>published in MICRO No. 62 July 1983, p. 36-41.

[much useful info deleted.]

>Your handler should:
>1. Save the X, Y, and P registers.

You don't need to save the P register.  It is pushed on the stack by the 6502.
This is the reason you have to use RTI rather than RTS.  However it wouldn't
hurt to save it.

>Charles Putney's address is
>18 Quinns Road
>Shankill
>County Dublin, Ireland

>Phil Goetz
>PGOETZ@LOYVAX.bitnet

					Scott
_______________________________________________________________________________
Scott Kempf                          Blue itself teaches us blue.  -Bill Ranson
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