44 on-screen colours from a CoCo 1/2 or Dragon 32/64

Hardware Hacking, Programming and Game Solutions/Cheats

44 on-screen colours from a CoCo 1/2 or Dragon 32/64

Postby zephyr » Sat Feb 02, 2013 12:24 am

Some interesting VDG tricks from John W. Linville. 8-)

http://vdgtricks.blogspot.co.uk/
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Re: 44 on-screen colours from a CoCo 1/2 or Dragon 32/64

Postby robcfg » Sat Feb 02, 2013 1:00 am

It's been some time that I did read this article, but I didn't manage to get the code working.

If anyone with better Dragon coding skills could create a disk or tape file with the program for running on the Dragon, it would be very appreciated.
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Re: 44 on-screen colours from a CoCo 1/2 or Dragon 32/64

Postby linville » Mon Feb 04, 2013 4:00 am

The code is a bit hack-n-slash, as I did that project in a little more than a week. I'm planning to use the code as the basis for another project, in preparation for CoCoFEST! When I get there, I'll try to take some time to see if I can generate a CLOADM'able file that runs on the Dragon...
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Re: 44 on-screen colours from a CoCo 1/2 or Dragon 32/64

Postby robcfg » Mon Feb 04, 2013 8:59 am

That will be great!

Thank you very much, Sir!
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Re: 44 on-screen colours from a CoCo 1/2 or Dragon 32/64

Postby Sarah » Wed Feb 06, 2013 6:26 am

That's very cool, especially if it works on a Dragon too!
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Re: 44 on-screen colours from a CoCo 1/2 or Dragon 32/64

Postby linville » Wed Feb 06, 2013 3:39 pm

I poked at it a bit the other night, but I was having some trouble figuring-out where/how to load the code without BASIC clobbering it or whatnot. My development environment uses a monitor program over a serial port, so I can avoid this kind of stuff for simple experimentation. I'm sure I can figure it out, may just take a little longer...
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Re: 44 on-screen colours from a CoCo 1/2 or Dragon 32/64

Postby linville » Sun Feb 10, 2013 2:21 am

OK, I got a chance to work with things a bit more today. I now have some images available for download.

http://www.tuxdriver.com/download/vdgtricks/

The bad news, of course, is two-fold: the diskette image is for the CoCo; and the binaries are for NTSC video.

I don't think any of my usual tools understand Dragon DOS format, so I didn't produce any such images. I could probably remedy that, if someone will direct me to some appropriate (and Linux-friendly) tools for that...

I don't have any PAL CoCo or Dragon machines. I think the binaries could be tweaked a bit to run on PAL, if someone wants to work with me on that. Some simple hacking on paltest1.asm should be sufficient to reveal what is necessary -- probably just increasing the count of non-displayed lines. Without such tweaks, I imagine you will only see a rolling mess.

In the meantime, if anyone has an NTSC CoCo or a Tano Dragon, then give these binaries a try!
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Re: 44 on-screen colours from a CoCo 1/2 or Dragon 32/64

Postby zephyr » Sun Feb 10, 2013 2:29 pm

Do all of your routines work correctly under XROAR emulation of the US CoCo 1/2 and Tano Dragon 64?
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Re: 44 on-screen colours from a CoCo 1/2 or Dragon 32/64

Postby linville » Sun Feb 10, 2013 5:20 pm

I didn't immediately find suitable Dragon ROM images -- pointers welcome!

I did run xroar with NTSC CoCo emulation, and the published binaries do more-or-less work there. There seems to be some "glitches" every few seconds, but the overall effect it visible. Maybe Ciaran will take an interest in fixing that up? This appears to be xroar version 0.29.1 as obtained for Fedora 17 from the RPMFusion repository, FWIW.

I guess that is a good point -- maybe the emulators are good enough to work-out the issues with running on PAL machines...
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Re: 44 on-screen colours from a CoCo 1/2 or Dragon 32/64

Postby zephyr » Sun Feb 10, 2013 6:29 pm

linville wrote:I didn't immediately find suitable Dragon ROM images -- pointers welcome!

You will find them all here.
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