*** M E M O R U M ***

Hi there

I read that the VDP supports RGB. I have my 512 hooked up with composite video, pretty mediocre picture quality, and I would like to try RGB. I also have some colour problems where a red line drawn with a RST10 call looked yellow. Might be the TV. Also, a line drawn against the left hand border is off screen (I read about scanning issues for the VDP so it's probably that).

Anyway, what's the easiest way to get RGB?

Thanks

JonB

Hi Jon,

this does not answer your question, but you might find it interesting (equally, you might not!).

http://primrosebank.net/computers/mtx/mtx512_video.htm

There's not an easy RGB solution, but component video (YUV) **should** be much more "doable", but we have not worked out a solution yet - the colour balance of the raw YUV signals is off and needs some adjustment, probably just resistors, to get it to work, but it needs looked at,

regards
Dave

JonB wrote:I read that the VDP supports RGB. I have my 512 hooked up with composite video, pretty mediocre picture quality, and I would like to try RGB. I also have some colour problems where a red line drawn with a RST10 call looked yellow. Might be the TV. Also, a line drawn against the left hand border is off screen (I read about scanning issues for the VDP so it's probably that).

Anyway, what's the easiest way to get RGB?

The VDP as fitted to MTX machines cannot produce RGB

MTX machines can produce RGB (well VGA is RGB, just with a faster scan rate...) with Andy's REMEMOrizer

This is not really helping you though - sorry

It is possible to convert the component video from the VDP to RGB, but it is not easy (as you may know, the Spectrum community has been talking about this for a while).
It may also be possible to make a plug in board that has a more modern VDP that does produce RGB video. But no one has done this AFAIK (well not yet).
It *should* be possible to convert the component video produced by the VDP to the type of component video that a modern TV expects. But again, this is not easy.

Mark

I'd be happy with composite, if it could give a better picture. Maybe some new capacitors in the video circuit? The Acorn Atom is the same, once the caps start to fail, the video signal goes wonky. New caps in, and the picture is crisp.

Got the REMemorizer on order, but the 80 column output is not used by BASIC, ASSEM or PANEL, so I hear. I'm hoping I will find a good assembler, debugger, editor under CP/M.

JonB wrote:I'd be happy with composite, if it could give a better picture. Maybe some new capacitors in the video circuit? The Acorn Atom is the same, once the caps start to fail, the video signal goes wonky. New caps in, and the picture is crisp.

Yes, that's because as electrolytic capacitors age, their high frequency response degrades. Replace with new and the picture should improve. Most are on the plug in video board.

JonB also wrote:Got the REMemorizer on order, but the 80 column output is not used by BASIC, ASSEM or PANEL, so I hear. I'm hoping I will find a good assembler, debugger, editor under CP/M.

Mostly, only CP/M programs use the 80 column output. There is a CP/M version of MTX BASIC.

Mark

Does the cpm MTX Basic include ASSEM? That's what I really want on the 80 column display!

Hi Jon,

yes it does!


regards
Dave

Another stooped question. It says here that CP/M doesn't support graphics. But that doesn't stop me programming the VDP direct does it?

In other words, I could assemble and run a VDP program in CP/M just as easily as I could in ASSEM..

CP/M does not support graphics - true.
But CP/M is just a operating system. As long as your code does not trample over the area used by CP/M (assuming your program wants to continue to use CP/M functions) then you can do what you want, including your own graphics code.
Think of CP/M as like DOS on the IBM compatibles, but on a Z80 system

Mark

PS please do keep us informed of you progress

Yes, please, keep us posted!

As an aside, the Memotech implementation of CP/M does actually support "graphics", even though they are very basic, line drawing, basic "block" type graphics etc.

regards
Dave