Re: [stella] Megacart Specs

Subject: Re: [stella] Megacart Specs
From: Chris Wilkson <cwilkson@xxxxxxxxxxxxx>
Date: Sun, 12 Apr 1998 17:51:31 -0700 (PDT)
> At 21:39 11.04.98 -0700, you wrote:
> >The idea is to make large amounts of ROM available (128KB) with the option
> >to tack on some RAM and an even more optional battery backup.  I forget the
> >numbers I quoted way back when, but I think the whole thing was gonna cost
> >around $15 for a complete cartridge minus labels/docs.  And that was gonna
> >come down a bit.  I think the cost of a ROM only cart was gonna be about
> >$8.  But it's been a few months since I was working on costs.
> OK, I just saw Randy's 4kb carts for $16 and thought adding more
> ROM, RAM and bankswitching logic would exceed the $20-$25 limit,
> that most people have for new games for classic systems. But if
> the carts would be that cheap, they would be ideal for the Mortal
> Kombat clone.

Well, this is parts only.  When you add Randy's fees plus author royalties,
this still comes out to $25.  Pretty expensive in my book.  But like I said,
I hope to bring the cost down considerably.

> Do you have cheap develloper boards with RAM to load the game into,
> or would I have to buy an expensive eprom emulator?

Heehee.  I have to get the Megacart itself working to specs first.  I was
developing a parallel port developer's kit.  Hopefully, these would cost
under $50.  But it got shelved when I ran into problems with bus contention
in the Megacart itself.  I hope to get back to it before this summer.

> >One last thing...
> >If anyone here has suggestions or requests for the document, or the spec
> >itself, now is the time to make them...while it's still in development.
> What isn't completely clear to me is, if the RAM banks are limited
> to $f000, or if they can be mapped into all four banks.

Memory is memory as far as the cartridge is concerned.  ANY block, ROM or RAM,
can go into any slot.

> If it isn't too complicated or expensive, a nice thing to add to
> the board might be some sort of Pitfall2 extra chip support. I
> think of something like you have one address, where you put in
> a ROM bank number, and another address, that would give you
> the next byte of that bank, everytime you read from it. That
> would allow volume samples or more complex graphics like in 
> Pitfall2. Would this be possible?

I'm not sure how that guy works.  But I don't think it directly affects the
graphics.  However, it might free up processor cycles, which would allow more
time to do graphics stuff.  Can anyone enlighten me here?

Hmm.  Maybe for the 2nd Generation Megacart.  But learning how that chip
works and integrating it into the existing design is a little too much for
me right now.  I have to do this in my spare time after a full day of
hardware design at Intel.  You guys who write software all day, then come
home and develop these games know what I mean ;)

Now that I think of it, I'm pretty sure that the Pitfall2 chip is a ROM
chip, not RAM.  Therefore it is specific to Pitfall2 and couldn't be used.
Maybe a POKEY could be added.  But again, not until Release 2 of the Megacart.


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