>From: Francois Lanciault <[EMAIL PROTECTED]> 
>Subject: Re: [Ql-Users] Hi Resolution Colour Graphics on a Standard

>I came up with the same trick many years ago, although 
>I only implemented the 256 x 256 (two mode 8 screen) 
>hi color display. 

Hi Francois, that's great. I am glad to read that you did it before. The
method of mixing colors or increasing resolution (interlace) is known
really long time. Even mixing hi-res with lo-res is not from my head.
C64 and CPC demos are using it very often.

>I produced a demo disk 
>including about 5 colorful images. It was sometime between 
>1990 and the end of 1993... 

I am very interested in your demo disk. Would you be able to find the
disk (or files) and send it to me? I would put it on my web if you
agree. I am very interested how you managed to convert the images and
display them.

>I showed the result at the Bedford 
>U.S. QL show to a few people but nobody seemed to care. 
>That put an end to my hi color research on the QL...

I know what you mean. It looks there are people interested in it now.

> ------- 
>From: Ralf Rek?ndt <[EMAIL PROTECTED]> 
>Subject: Re: [Ql-Users] Hi Resolution Colour Graphics on a Standard

>I remember, that Steve Sutton also implemented a way of mixing Mode 4 &
Mode 
>8 in his adventure creation program from DP (have forgotten the
name....). 

I know about this game. Split screen is something else to mixing colors.
On text adventure, the screen is usually split to half - graphics on the
top is low-res and text in the bottom is high-res. That's easy.

Dithvide mixed mode works following:

1st interrupt: 
line 1: Lo res, screen 1 
line 2: Hi res, screen 2 
line 3: Lo res, screen 1 
line 4: Hi res, screen 2 
... 
etc. up to line 256

2nd interrupt: 
line 1: Hi res, screen 2 
line 2: Lo res, screen 1 
line 3: Hi res, screen 2 
line 4: Lo res, screen 1 
... 
etc. up to line 256

The goal is different. Every line is using different screen and
different screen mode in order to have pixel color given by average
value of the pixels from screen1 and screen2.

Display looks stable using this interleaved routine. On the other hand,
it makes this mode less useful for games, because it's CPU intensive due
to timing of every line.

To Rich, 
I see no problem to use hi-color in games, it only requires to "resign"
from QDOS friendly application style programming and use the machine as
"hardware" to run your "software". It's the same as ZX Spectrum game
developers do with ZX Spectrum. Games like Frozzen Bubble, Prince of
Persia, Lemmings would "go" on QL. I am sure.

Javier Guerra wrote:
> and the exe file ASM_... don't work.
I know, unfortunately this is all I have. My wife splashed water onto QL
while she was ironing and the Sandy interface is now in cyber heaven.
Before it died, the floppy with source and all data was damaged. I have
only this file backup on PC disk... ===> little advert: if anyone has
some spare Sandy, I am interested.

Try to LBYTES the file and SEXEC it with e.g. 1024 bytes of data stack.
If it would crash, try to increase it.

> Another cuestion:
> this code will run whit a RGB TTL monitor?

Absolutely, as you can see it my QL is connected to Commodore 1084
monitor.

Dilwyn Jones wrote:
> I don't know if a TTL monitor
> would switch too fast, so you see flickering black and white instead of
> fuzzier grey on a TV set. 

Yes you are right, you need to decrease contrast on the monitor to make
the display more stable. Some monitors are very fast and this effect is
better on slower monitors. I also tested ZX on dataprojector and similar
effect was completely stable. The electronic averaged the screen without
flickering.

> I don't think the software can run on an emulator
> (no mc.stat register and probably timing issues too). 

The issue is rather timing of the CPU with ULA. There is no QL emulator
that does it. Well, there was no need for it.

> And Jan says on his
> website it might not work on anything faster than Sandy SuperQBoard
> interface, so no Gold Card, no Super old Card :-(

Yes, that's partly true, basic modes - low res and high res should work
on all systems (not SMSQ?, Minerva). Mixed mode needs to be finetuned by
two delay constants for GC, SGC - it's not really too complicated. I
would appreciate if someone would find the right numbers for his
hardware.

In fact, initialization sequence with speed detection would be the best.
I wonder if this was done before?

Jan

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