[stella] Understanding the PIA

[seagtgruff at aol.com]

I think I can run some tests tonight-- 2600, 7800, z26,?Stella-- and maybe even PCAE to boot! I'll test

(1) all timer intervals (1, 8, 64, and 1024);
(2) when the timer interrupt flag gets set;
(3) how the timer decrements after first wraparound but before reading TIMINT;
(4) how the timer decrements after first wraparound after reading TIMINT;
(5) how the timer decrements after second wraparound but before reading TIMINT;
(6) how the timer decrements after second wraparound after reading TIMINT.

Can anyone think of anything else?

Michael

-----Original Message-----
From: bob.montgomery at thomson.com
To: stella at atari2600.org
Sent: Fri, 4 Apr 2008 10:49 am
Subject: Re: [stella] Understanding the PIA



Hi,


>OK, now I'm just really confused.  There's the documentation that you 
>provided from nocash, and the actual implementation in Stella that say 
>this is how it should work.  However, z26 and MESS don't do it that 
>way, and they produce the results that you guys say is correct.
>
>At this point it's not a matter of fixing a bug in the emulator; I have

>code that does it both ways.  What I need is confirmation of *which* 
>way is correct.

Sounds like someone needs to test on a 2600.  I'll try to make time for
that, but I don't know when I'll get to it.

-Bob

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