Re: [stella] TIA internals

Subject: Re: [stella] TIA internals
From: "Frank Palazzolo" <palazzol@xxxxxxxx>
Date: Thu, 10 Jan 2002 23:29:30 -0500

> If you decide to do this, I am interested it taking part.  I've figured
> out the overview of just about the entire thing; and a fair chunk of the
> gritty details.

Ok, I'll start by making a list of the sections and how well I understand them.
Maybe we can fill in the blanks then.  I figure any annotation is better than 
none :)

> My favorite parts are the playfield registers, and the divide by 3
> counter.

The divide by 3 is really neat.  I haven't looked at the playfield registers yet. 
I'm still trying to grok the horizontal position register section.  I know what it 
does, but I can't quite see how yet. :)  I really want to know if you can do any 
other stars-like effects by "misusing" that section.

The sync counter is became easy to understand, once I realized that the lsb 
is on the left, and the numbers in parens on the compare lines are octal.  
That took me a while to figure out, so I think putting little things like that in 
the guide would be a good idea.

> > I've also discovered "TkGate", a digital logic simulator that runs on
> > Linux.  I've been successful at putting some of the pieces in there to
> > see how they work.
> Cool.  Does it support the persistant effects of the MOS transistors?  Or
> did you mimic that with some latches?

Good question.  Well, so far all I've done is the divide-by-3 circuit, which doesn't have the transistors.  
I'll see what it can do with the FET's next.  I may have to use latches or just 
an equivalent circuit for the block in question.

> > Finally, I really think recreating a new TIA in a programmable logic
> > chip really would make a lovely project for an EE student.
> Quite so.  Care to take it on?

Well, if I wasn't becoming a daddy in 4 short weeks, I would...but I think I'd 
better choose my projects carefully in the short term. :)  I'm just getting 
prepared for when I do have the time.

It looks like Chris Wilkson is doing an even harder job...I just found this link:

Look at his entry about halfway down the page.


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