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From: miller@uiucdcs.UUCP (miller )
Newsgroups: net.micro.cbm
Subject: Re: Problems with V2 C64 and joystick - (nf)
Message-ID: <5302@uiucdcs.UUCP>
Date: Wed, 1-Feb-84 22:36:10 EST
Article-I.D.: uiucdcs.5302
Posted: Wed Feb  1 22:36:10 1984
Date-Received: Tue, 7-Feb-84 15:32:17 EST
Lines: 23

#R:security:-63300:uiucdcs:36100033:000:857
uiucdcs!miller    Feb  1 15:10:00 1984

I thought everyone knew what the CTRL key does on the c64, hence I didn't
explain it in my note on the joystick port 1 bug.  But I got mail from people
who didn't know so I'll explain its purpose now.  What it does is slow down
your machine.  It is mainly used in slowing the LIST down for Basic.  However,
it also will slow down *execution* of user programs too.  This is true of both
Basic AND machine language.  For example, try the following programs on your
machine with/without the CTRL key down:

10 PRINT "A";: GOTO 10
  - or -
START LDA #'A'
      JSR CHROUT ;kernal print routine.  see Programmer's Ref. Guide
      JMP START

I'm not really sure why it slows down machine language.  I guess the interrupt
processing routines in the OS have a delay loop they jump to when that key is
depressed.  Anyone know for sure?

A. Ray Miller
Univ Illinois