video segment: where is it?

Discussions on programming older machines

Re: video segment: where is it?

Postby Trixter » Thu Dec 28, 2017 8:34 pm

riq wrote:
Trixter wrote:It's good enough for testing. I'm not sure it supports everything 100%, like the 160x100 video mode I invented, but it should work for basic purposes.


Interesting. Did you document the video mode that you discovered somewhere? I would like to try it in the future.


Yes, code is attached. It doesn't work on a Tandy 1000 (there is a blank line every other line) but NewRisingSun found a way to make it work on Tandy 1000 series. Unfortunately I can't find his notes right now, but they're on the web somewhere.
Attachments
PCJRSUPP.TXT
PCjr support routines
(12.98 KiB) Downloaded 14 times
You're all insane and trying to steal my magic bag!
Trixter
 
Posts: 495
Joined: Mon Sep 01, 2008 12:00 am
Location: Illinois, USA

Re: video segment: where is it?

Postby riq » Thu Dec 28, 2017 10:37 pm

Trixter wrote:Yes, code is attached. It doesn't work on a Tandy 1000 (there is a blank line every other line) but NewRisingSun found a way to make it work on Tandy 1000 series. Unfortunately I can't find his notes right now, but they're on the web somewhere.


Thanks and nice discovery!
I'll search for the Tandy1000 code.

riq wrote:Apparently 0x3da bit 0 works as horizontal retrace... but for some reason, sometimes hangs in part of my code (should double why)


As is often the case, when I blame the hardware, it is usually my code. While converting from Tandy 1000 to PCJr I left a "mov dx,bp" that was causing the crash.
On other new I managed to have a "stable rasterbar" on the PCJr. Not a big deal, but from having a "horiz retrace crashes my machine" to a "stable raster" is a big progress for me :)

Image

It is just a horizontal retrace + nops, and the garbage is not seen since the border covers it.
riq
 
Posts: 26
Joined: Sat Dec 09, 2017 2:36 pm

Re: video segment: where is it?

Postby Trixter » Fri Dec 29, 2017 1:41 pm

Looks like you did better than I did -- introJR has moving raster bars, but they aren't stable (they have noise).
You're all insane and trying to steal my magic bag!
Trixter
 
Posts: 495
Joined: Mon Sep 01, 2008 12:00 am
Location: Illinois, USA

Re: video segment: where is it?

Postby riq » Fri Dec 29, 2017 9:20 pm

Trixter wrote:Looks like you did better than I did -- introJR has moving raster bars, but they aren't stable (they have noise).


In case you want to take a look at it here is the code:
https://github.com/c64scene-ar/tandy64/ ... r.asm#L200

I noticed that if the noise is moved too far to the right, it will generate even greater noise (for example: in my code use 340 nops instead of 335 when doing "fat raster bars").
Perhaps that "even greater noise" could be used as a feature instead of a bug... I'll try to find a use for that.
riq
 
Posts: 26
Joined: Sat Dec 09, 2017 2:36 pm

Previous

Return to Programming

Who is online

Users browsing this forum: No registered users and 1 guest

cron