[Coco] Anyone try an 80x28 text screen on a CoCo3?
L. Curtis Boyle
curtisboyle at sasktel.net
Mon Apr 23 06:22:31 EDT 2018
I think the reason Tandy didn’t enable that mode is that, on quite a few TV’s (at the time) would run off the top and bottom of the screen, making both the first and twenty-with line unreadable. We had an option on NitrOS9 builds to enable the 225 scanlines on 80x25 (which added a blank scanline between each text line, giving better separation between characters vertically, making it much easier to read), but you pretty well needed an RGB monitor to see it properly. TV owners told us to put it back to 200 scanlines again; so we made it a flag at assembly time to let us generate both versions. (hmmm ... I think I will add this to the upcoming SS.GIP2 call so that one can change it on the fly).
Sent from my iPhone
> On Apr 23, 2018, at 1:32 AM, Robert Gault <robert.gault at att.net> wrote:
> Many of you know that the GIME can be set for a max 225 lines on a screen; the default being 192.
> I've just found a method for patching the ROM so that a WIDTH80 screen now displays 28 lines of text rather than the default 24; 192/8=24.
> Let this be a challenge for you programmers. :) You also need to realize that 225/8=28.125 which will give you an extra horizontal scan line. That needs to be cleared with a CLS from the bottom of the screen.
> I'll see if there is any interest in this and post the answer after you have a chance to try and solve the challenge.
> I wonder why Tandy decided to use 24 rather than 28 lines of text.
> Coco mailing list
> Coco at maltedmedia.com
More information about the Coco