Re: [stella] 2600 questions

Subject: Re: [stella] 2600 questions
From: Glenn Saunders <cybpunks@xxxxxxxxxxxxx>
Date: Tue, 20 Jun 2000 21:14:24 -0700
At 10:36 PM 6/20/2000 -0500, you wrote:
suspect it wasn't that the early games needed the program time, but that
they didn't have the experience yet to realise what all could be done.

It's also incredibly memory efficient. The kernel can be a lot smaller that way. Less data, less instructions.

If you know that a particular zone won't have dynamic players, you can probably hide a lot of number crunching in there.

Yes, paddle reads must be done during the screen.

How many scanlines can you spread out the reads in order to still achieve accurate results?

I had always wondered about that 'score' bit.  I mean it is theoretically
great for doing scores at the top of the screen like in airsea
battle.  The thing I don't understand is because I think this is why it
was designed this way when they designed the TIA, but that would imply
that when they designed the TIA, they knew that they could do playfield
updates mid line.  I had thought that this was a later revalation...

There is another line in the documentation that reads something like "these registers are available to be written to at any time" although it does warn about doing successive HMOVEs too close to eachother.

It doesn't say you SHOULD rewrite registers in mid scanline, but it does explicably leave it wide open for experimentation.

In the interview I'm editing still, Larry Wagner states that Jay Miner deliberately wanted the timing to work out in such a way that the 6507 and the TIA lined up very well. Jay may not have known that there would be just enough CPU time and that the TIA responds just fast enough to do the six-digit-score, let alone slide it around with NOPs and stuff, but I think it's a byproduct of Jay's thinking.

Never heard anything of it.  It is 100% doable.  the 6532 is a stock part,
and those pins are simply not connected.

Anyone have any ideas?

may want to catch.  With the latch, you can catch all presses, no matter
how fast(I lie, the speed is limited to the transistor speed, but that is
pretty darn fast).

With the latching, most 2600 games won't allow autofire over 30 times a second then, right? One on and one off state on alternating frames?

What happens when you hold down the fire button close to the end of a frame and in the middle of the next frame you release it and then manage to press it down again by the end of the frame? What state will the register be in when it's read in vertical blank?

It's probably not physically possible to do that anyway :)

Glenn Saunders - Producer - Cyberpunks Entertainment Personal homepage: Cyberpunks Entertainment:

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