The SECRET VIDEO MODE in an ST: 400 lines in COLOR (and with 72 Hz)!

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Re: The SECRET VIDEO MODE in an ST: 400 lines in COLOR (and with 72 Hz)!

Postby leech » Thu Aug 09, 2018 3:51 pm

troed wrote:So while not as awesome as this trick, since it requires an extensive hardware upgrade, some of you might recall the doubleST video modes I documented here: https://blog.troed.se/projects/atari-st ... deo-modes/

Combining that upgrade with this trick will result in:

320x400x16
640x400x4

(and 2560x200x2, but let's just forget how ludicrous that would be;))

Unfortunately, there are no vertical borders that can be opened with the GLUE in high res so the tantalizing 640x480x4 cannot be done.

2560x200x2.... UltraMegaWide!
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Re: The SECRET VIDEO MODE in an ST: 400 lines in COLOR (and with 72 Hz)!

Postby shoggoth » Thu Aug 09, 2018 5:05 pm

leech wrote:2560x200x2.... UltraMegaWide!


In practice, that's a chunky grayscale 320x200. Awesome.
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Re: The SECRET VIDEO MODE in an ST: 400 lines in COLOR (and with 72 Hz)!

Postby ijor » Sun Sep 16, 2018 1:59 pm

Re: avoid BLANK being asserted on the STE

troed wrote:Well running GLUE in color during active display should work, right? Still only two changes per scanline.


Did you have a chance to test it? Is it messing with SYNC?

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Re: The SECRET VIDEO MODE in an ST: 400 lines in COLOR (and with 72 Hz)!

Postby troed » Sun Sep 16, 2018 2:31 pm

No time yet, but I think you're right in that a switch to avoid mono hsync will be needed.

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Re: The SECRET VIDEO MODE in an ST: 400 lines in COLOR (and with 72 Hz)!

Postby ijor » Sun Sep 16, 2018 2:55 pm

troed wrote:No time yet, but I think you're right in that a switch to avoid mono hsync will be needed.


You probably mean to avoid a COLOR (not mono) hsync. Not sure how good it would work. You probably might be able to avoid the COLOR hsync, but you will have a couple of problems. You would still run a few cycles with GLUE in mono during active display and then with BLANK asserted. Also the switch might destabilize SHIFTER.

You might be able to get along with a reduced width screen, shifted to the left, before the COLOR HSYNC position.

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Re: The SECRET VIDEO MODE in an ST: 400 lines in COLOR (and with 72 Hz)!

Postby troed » Sun Sep 16, 2018 2:59 pm

Yeah, sorry, exactly :) I calculated how far into the screen that black area would be and it was substantial.

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Re: The SECRET VIDEO MODE in an ST: 400 lines in COLOR (and with 72 Hz)!

Postby ijor » Sun Sep 16, 2018 3:26 pm

troed wrote:Yeah, sorry, exactly :) I calculated how far into the screen that black area would be and it was substantial.


I would need to check the GLUE/MMU combo schematics to see what happens if you use a resolution with value = 3. On GLUE ST it wouldn't help, it considers this the same as 2 (mono).

Btw, and sorry for going a little off topic, Smonson told me about your reset problem with his FPGA board. It is surely that the CPU is reading the wrong resolution value from the FPGA.


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