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From: kamath@reed.UUCP (Sean Kamath)
Newsgroups: net.micro.apple
Subject: Re: Apple IIe and IIc raster scan synchronization.
Message-ID: <4160@reed.UUCP>
Date: Sat, 27-Sep-86 02:31:32 EDT
Article-I.D.: reed.4160
Posted: Sat Sep 27 02:31:32 1986
Date-Received: Tue, 30-Sep-86 07:18:54 EDT
References: <2869@sdcc6.ucsd.EDU>
Reply-To: kamath@reed.UUCP (Sean Kamath)
Organization: Reed College, Portland, OR
Lines: 43
Keywords: IIe IIc video

In article <2869@sdcc6.ucsd.EDU> ir332@sdcc6.ucsd.EDU (Jeff Miller) writes:
>I need to synchronize a program with some fixed point in the video
>display cycle (i.e. raster scan) on IIe's and IIc's.  I have done
>this on II+'s by wiring a certain pin into the game port, and then
>reading the status of the game port.  I would like to do the same
>thing for the other II machines, but I don't know which pin it is
>(or even whether there still is one that will work).  To boot, I
>can barely solder, so don't refer me to some technical specs.
>Anybody out there who can help for either machine?  Thanks.
>
>        Jeff Miller

Solder my precious //e?  Never!  Well, maybe.  On the //e and //c there
is no need to solder a pin. It has already been done for you.  Read
$C019.  When it goes low (<128), it is in VBL.  For some really neat
programs that take advantage of that, look into "Enhancing Your Apple ][
Vol. 2" by Don Lancaster.

On the //c it is possible to generate interrupts when VBL ($C019) goes
low.  I KNOW this.  I THINK the same can be done on a //e with a mouse
card, but I'm not altogether sure.  If anyone is dying to know, I'll do
that before I work on my color printing routine...


________________________________________________________________________________

Sean Kamath

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