The Sinclair QL Forum

I do seem to recall that Aurora had a bit of a weird video memory layout with constant line lengths independent of resolution (that is, unused bytes at the right-hand end of the scanline).

pjw wrote:Mode 16 is 8 bit, so should be 40,000+10.

According to superbasic-manual we have 16 color mode and this mode uses a byte to store the colors of 2 pixels. And we have 256 Color Mode and this mode uses a byte to store the color of single pixel. So your CW200-16.pic actually is image in 256 Color Mode?

tofro wrote:I do seem to recall that Aurora had a bit of a weird video memory layout with constant line lengths independent of resolution (that is, unused bytes at the right-hand end of the scanline).

Yes, the fixed display line width. Remember getting confused by that when saving screens with a simple SBYTES command on the Aurora. That would save the unused part of screen memory along with the display. Weird.

The 16-colour mode was never really supported by anything, although it was available in hardware on an Aurora. To all intents and purposes, forget about it and focus on the 8-bit and 16-bit colour modes as the only ones in any real use.

I may be stating the obvious here for Dec. The "original" display format documents from Tony Tebby are available on my website's GD2 & WMAN2 page:

http://www.dilwyn.me.uk/gd2/smsqe298doc.zip plus other docs about the slightly later WMAN2 systems.

Other documents you may find useful are here: http://www.dilwyn.me.uk/docs/smsqegd2/index.html

pjw wrote:Here are samples of this image in mode 16, 32, and 33

ColorWheel200.jpg (14.68 KiB) Viewed 2394 times

I tried to convert CW200-16.pic into bmp and I see the following:
Is it correct image or something wrong with my algorithms?

Dec wrote:

pjw wrote:Here are samples of this image in mode 16, 32, and 33
ColorWheel200.jpg

I tried to convert CW200-16.pic into bmp and I see the following:

CW200-16.png

Is it correct image or something wrong with my algorithms?

That looks about right

Dec wrote:

pjw wrote:Mode 16 is 8 bit, so should be 40,000+10.

According to superbasic-manual we have 16 color mode and this mode uses a byte to store the colors of 2 pixels. And we have 256 Color Mode and this mode uses a byte to store the color of single pixel. So your CW200-16.pic actually is image in 256 Color Mode?

Yes What a mess! But I dont make the rules. Some of them are just evolutionary debris..There are QL modes ( 0 (aka 4) 8, 12, ..) and then a whole bunch of GD2 modes (0, 3, 4, 7, 8, 15, 16, 31, 32, 33, 64). I really only care about the "real" modes 16, 32, 33, & 64, and of sad necessity, QL modes 0 and 8. I havent really explored the rest. Maybe they are useful, or will be found to be, one day.

pjw wrote:I really only care about the "real" modes 16, 32, 33, & 64

I have updated my tool, now it supports Mode 16. Could you test it? Tool does NOT add extra bytes in PIC file, so let me know if it can cause a problem.

Also I have a question about pixel aspect ratio in extended screen modes.

Remember that MODE 16 is *NOT* the 16 colour mode, it's the 8-bit 256 colour mode.

The operating system generally draws graphics for a 512x256 ratio screen (original QL), but it's perfectly possible to have 4:3 and other ratio modes and resolutions on the differing platforms out there. Circles not being circular is one of the most frequently asked questions about QL graphics.

There's a useful little utility for SMSQ/E users to change the ratio if you need to when drawing graphics, called G-ratio, from Jens Wildgruber. Can be downloaded from Graphics page on my site: http://www.dilwyn.me.uk/graphics/index.html

Dec wrote:

pjw wrote:I really only care about the "real" modes 16, 32, 33, & 64

I have updated my tool, now it supports Mode 16. Could you test it? Tool does NOT add extra bytes in PIC file, so let me know if it can cause a problem.

Also I have a question about pixel aspect ratio in extended screen modes.

Sure - if I can find it somewhere..

pjw wrote:if I can find it somewhere..

Do you mean find a link to download the tool? If yes - in this post.