[A83] Re: Direct Input...

To: assembly-83@lists.ticalc.org
Subject: [A83] Re: Direct Input...
From: Peter-Martijn Kuipers <hyper@hysoft-automation.com>
Date: Sat, 25 Aug 2001 15:07:30 +0200 (CEST)
In-Reply-To: <003301c12d64$4a7d9c10$4100000a@brinstar> from "David Phillips" at Aug 25, 2001 05:48:50 AM
Reply-To: assembly-83@lists.ticalc.org


I never used nop's between input and output, and it worked fine.

 
> 
> All code I've seen uses 2-4 nops between the out and the in.  I've always
> used 2 in my code and haven't ever seen any problems on the real hardware.
> The code in the ROM for both the 83 and 86 uses 4.  The relevant portion of
> the ROM (same on both calcs) is shown below:
> 
>  out (1),a
>  nop \ nop \ nop \ nop
>  in a,(1)
>  ld b,a
>  ld a,$ff
>  out (1),a
> 
> I don't remember ever having to reset the port when reading keys (but maybe
> I never read more than the arrows using the ports).
> 
> > With 'Direct Input' you have to reset the keyboard (via outputting $FF
> > trough port 1), do you have to wait a little for the hardware to react? Or
> > can you just go on with the next output (to actually switch the the
> > groups)?
> 
> 
> 
>

References:

[A83] Re: Direct Input...

From: "David Phillips" <david@acz.org>

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