SCREEN $80 configuration

kelli217 · Post by **kelli217** » Mon Feb 08, 2021 6:42 am

Right now, SCREEN $80 (or SCREEN 128) in BASIC opens up a display mode that features 320×200 graphics, but it's locked to the top of the visible area, and leaves a black bar at the bottom.

I understand that there are reasons why it's only 200 pixels tall, and that trying to make it 240 pixels tall would interfere with the PSG registers’ locations in VRAM.

In the absence of being able to do anything about the height, then... can I ask for a more centered position? Maybe the code for bringing up SCREEN $80 could set DC_VSTART to come down 20 lines before drawing. That way, those extra 40 blank lines could be split up between the top and bottom of the display.

Lorin Millsap · Post by **Lorin Millsap** » Mon Feb 08, 2021 1:08 pm

That’s not really possible as that’s not how the vERA works.

Sent from my iPhone using Tapatalk

kelli217 · Post by **kelli217** » Tue Feb 09, 2021 7:14 am

SCREEN $80:POKE $9F25,PEEK($9F25) OR 2:POKE $9F2B,20:POKE $9F2C,220:POKE $9F25,PEEK($9F25) AND 253

kelli217 · Post by **kelli217** » Tue Feb 09, 2021 7:38 am

14 minutes ago, kelli217 said:

SCREEN $80:POKE $9F25,PEEK($9F25) OR 2:POKE $9F2B,20:POKE $9F2C,220:POKE $9F25,PEEK($9F25) AND 253

BTW, this won't fit on one line if it's fully typed out, with spaces as shown, so abbreviate keywords and eliminate spaces.

StephenHorn · Post by **StephenHorn** » Tue Feb 09, 2021 3:04 pm

Yeah, I'm a little confused by Lorin's response, because it seems kelli217 is asking for something like this:

If there's a particular reason the team doesn't want SCREEN $80 to alter and truncate the display area to a 320x200 resolution, that's cool. Maybe they don't want to track down all the other places where they'd need to reset that for swaps to other screen modes. But adjusting the display area is totally within the VERA's capabilities.

What the VERA can't do is adjust the native resolution. In that sense, it's locked to 640x480.

Lorin Millsap · Post by **Lorin Millsap** » Tue Feb 09, 2021 3:11 pm

Ok. I guess I did misunderstand the question. Sorry if I confused or mislead.

Sent from my iPhone using Tapatalk

Ender · Post by **Ender** » Wed Feb 10, 2021 2:02 am

I think SCREEN $80 mode was heavily inspired by GEOS (with some code taken directly from it), and if you take a look at GEOS it's set up the same way as SCREEN $80 mode currently is. That's probably the main reason why it is the way it is. It would be pretty simple to alter things slightly to be as kelli requested, as was shone. It's just a matter of aesthetics.