Re: [stella] RAM usage

Subject: Re: [stella] RAM usage
From: Glenn Saunders <cybpunks@xxxxxxxxxxxxx>
Date: Tue, 20 Jun 2000 19:45:45 -0700
At 09:45 PM 6/20/2000 -0400, you wrote:
No. The 128 bytes of RAM are in addition to the register space.

I thought that would be a little constraining, given that the designers were contemplating 64 bytes of RAM at one time.

Where is this memory stored then, inside the TIA?

Also, isn't the 128 bytes considered the 6507's page zero as well?

No and no.  From a programming standpoint (which you're unfamiliar
with), the scanline ends immediately at the right border of the visible
area... the right overscan area is for all intents and purposes part of
the horizontal blank region for the next scanline.

In the diagram from the Stella programmer's guide, the overscan is shown on the left and not the right.

From the perspective of the picture tube, however, are you saying that the overscan overlaps from the right back to the left?

How is the background color generated, BTW. Doesn't this color beyond the 160 pixels available to the playfield and sprites?

There IS extra space on both the left and right edge. How that works out as far as the TIA is what I'm curious about.

If the beam starts to retrace at cycle 76 then how can the background color continue on to the right?

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

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