A82: Re: a pong paddle, logically

To: <assembly-82@lists.ticalc.org>
Subject: A82: Re: a pong paddle, logically
From: "Dines Justesen" <c958362@student.dtu.dk>
Date: Fri, 24 Oct 1997 15:52:48 +0200
Reply-To: assembly-82@lists.ticalc.org



I did not test the rutine, but i had a look at the source code and found a
few things which should be changed.

>drawpaddle:
>   ld a, 7
>   call $7F3
>   out (10h), a
>   ld a,(paddlepos)
>   call $7F3
>   out (10h), a
>   ld a, $20
>   call $7F3
>   out (10h), a
>   call $7F3
>   in a,(11h)
>   and %10011111
You have to do two reads the first time otherwise this wont work.
>   call $7F3
>   out a,(11h)
>   ld b, 12
>repeat1:
>   call $7F3
>   in a,(11h)
>   or %01100000
>   call $7F3
>   out (11h),a
>   djnz repeat1
These two delays can be made a bit shorter. Sam Davies did some testing on
the delays need, have a look at that.
>   call $7F3
>   in a,(llh)
>   and %10011111
>   call$7F3
>   out (11h),a
>   ret
>
>
Almost all the delays in the rutine can be made short since the call $7F3
takes longer that what is need by the display controller. I can not remember
the exact number but i tkink you only need 20 T-states.

Dines

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