600x - Why not 1280x1024 @ 16-bits

[Lomax]

If I understand things corretly you need 4Mb of video RAM to get 1280x1024 with 64k colours but despite the 600x having 4Mb of video RAM it is not possible to run an external monitor at this resolution. When I try to change to 1280x1024 colour depth drops down to 256 colours.

I know that the spec for this macine clearly states 1280x1024 @ 8-bits as the maxiumum res, but why is this so!?

It's really annoying since I have a nice 19" TFT with a native resolution of 1280x1024 - scaled to 1024x768 things look a bit fuzzy and I could really do with the extra desktop space. 256 colours is not an option as it makes everything look pretty horrible...

Do you think it would be possible to hack the existing driver/registry or install another driver to get 1280x1024 w. 16-bits?

Many thanks,

Lomax

[whizkid]

After a quick look at the Linux driver setup, it seems the video chip has a cap on its memory bandwidth that is the real limit.

So while 1024x768x3(bytes)@60Hz should need ~141MB/s bandwidth, 1280x1024x3@60 would need ~234MB/s. I'd think 16 bit color would work, at ~157MB/s, but the best I've seen is 1152x864x2@71 =~141MB/s, and 1024x768x2@85=~134MB/s.

From those numbers, the chip "should" be able to do 1280x1024x2@54Hz or x3@34Hz. Ick.

[Lomax]

Thanks for the info whizkid, I take it it would be impossible to increase the memory bandwidth?

On another note, I have managed to get TV out to work but only after forcing an install of the IBM drivers (v5.39) in stead of the autodetected Windows 2000 drivers. I did this by locating all .inf files (in c:\windows\inf\) that contained the string "MagicMedia256ZX" and deleting them. A bit crude perhaps but it worked and I now have the NeoMagic tab under advanced display properties (Microsofts driver was missing this crucial tab).

I just wish I could somehow get 1280x1024 @ 16-bits externally and all would be perfect!

Lomax

[whizkid]

Thanks for the info whizkid, I take it it would be impossible to increase the memory bandwidth?

Utterly.

Well, way past worth the effort. In theory, you could increase the memory clock, or FSB, and replace each chip that couldn't handle the speed, then write a driver to handle the new mode since it's never been done... but that would just be sad.

It would be much more cost-effective to buy a more capable machine.