Re: 640x512x16bpp with VESA ?

Hello all and thank you for you supportive and informative answers !

Wolfgang Kern wrote:
"whygee" wrote:
Hello,
Hi,

Dunno what X.org does nor what it is ...
you know, the X11 server for GNU/Linux et al.

but I also have to use VESA/VBE to set Vmodes on newer PCI/AGP cards,
because they are unfortunately not at all documented in deep detail.
nobody cares to document these days :-(

I guess that I have to setup 1280x1024x16 then tweak the CRTC
by x16 you mean 16 colors on four distributed planes ?
or 16-bit colours ?

I display fixed pictures in 16-bit color (5-6-5 RVB).
My tests show that 24bpp is overkill and 16bpp saves some memory
(i don't care to compress the picture data, i have enough room
for a whole gallery :-P). On top of that, 24bpp would need to be in
32-bit aligned pixels to ease the random accesses.

Then, each pixel is computed and moved all over the screen,
using personal algorithms that make this kind of picture :
http://ygdes.com/sediments.jpg :-)
So 16-bit pixels is the good choice here.

to "double scan" (so i get 1280x512). I have read books 12 years
ago about this but i don't remember the particularities of the X mode :-)
I have to half the clock speed too but it's above my ability now
(i don't have the books anymore). Hint : my graphics chip is based on S3.
It will not be enough to set Vclock and double-scan, you need also
to recalculate synch/border/blank periods within the range of your
monitor.
that's what i guess, but i have not looked closely yet,
as long as i don't know how to change these in the S3 chip.

I remember good old S3-times quite well and I played around with
own created Video-modes of any kind, even a weird behaving mixed
Text/Graphic-mode were possible here.
:-)
I had some fun with a 286 in the mid-90s too :-)
but i kept on the track, fearing to burn my CRT.

My requirement is to conserve the 1:1.25 ratio of the screen
with practically fine values. If you know of other resolutions
that fit, fine, as long as I can set it with a simple asm program.

You got a 5:4 (better known as 10:8) monitor ?
monitorS :-) 16:10 LCD monitors are not old enough to be found
at "decent" prices in the used market :-) I have tested
a 640x400 resolution (stock VESA) with success on a 1920x1200 screen
but it's too expensive :-) The available hardware, the platforms and
a few other constraints guide the development.

I never used any 4-bit color format, my preference is and always was
8-bit (one byte/pixel serves me well)
Same for me. But here, 16bpp is the way to go.

and my standard resolution is
1152*864x256 to allow a 1024x768 display plus tool-bars and stuff,
so keeping the monitors 4:3 format (and circels remain 'round').

getting (and keeping) "square" pixels is very difficult today :-/

I once found all required information for S3(GL4x/5x..)in RBIL(ports).
This collection may be still on one of my old HDs, so if you don't
find it on the net, I could search my archives and post the few pages.
I downloaded RBIL recently. Wow, that is still extremely useful today !

BTW, I have read somewhere that recent Intel chips have MSRs that
control the core voltage and frequency, which would be incredibly
useful to reduce the power consumption of the Intel D201GLY2 motherboards
that i also want to use.
Has anybody found where/how to control this ?

Do you know which S3-chip is in there ?
It's an embedded PC in 5"25 form factor with a VIA C3 @ 800MHz.

The manual says :

VGA: S3 Savage4 on Die, 4X AGP, 2D/3D support,
32 MB shared Frame Buffer, TTL/ LVDS interface to Panels

copy-paste :
VIA 8606 Integrated Savage4 2D/3D/Video Accelerator
Optimized Shared Memory Architecture (SMA)
8 / 16 / 32 MB frame buffer using system memory <--- beware, this
can kick you in the back if you have only a 32MB or 64MB SDRAM module :-D
Single cycle 128-bit 3D architecture <--- useless
Full internal AGP 4x performance <-- more interesting, but yet, not lightning fast.
Next generation, 128-bit 2D graphics engine <--- well...
High quality DVD video playback <-- who cares ?
2D/3D resolutions up to 1920x1440
3D Rendering Features
Extensive LCD Support
36-bit DSTN/TFT flat panel interface with 256 gray shade support
Integrated 110 MHz LVDS interface
Support for all resolutions up to 1600x1200
Drivers support：Windows 95/98/2000, Windows NT4.0, Win XP, Linux.
15Pin D-Sub VGA Output,
LVDS Interface Connector x 1
TTL LCD Interface Connector x 1

I've uploaded the manual at http://ygdes.com/VIA/
if you want to see a bit more, all I know for sure is that it
is embedded in the VIA 8606 northbridge.

I have dumped the VESA2 listed modes with custom software
and it looks a lot like the S3 board i have in the laptop that i am now using
to type this post :

n°VESA X Y col Linux
100h 280h 190h 8 300h/769: 640x400x8
101h 280h 1E0h 8 301h/769: 640x480x8
102h 320h 258h 4 302h/770: 800x600x4
103h 320h 258h 8 303h/771: 800x600x8
105h 400h 300h 8 305h/773: 1024x768x8
107h 500h 400h 8 307h/775: 1280x1024x8
10Eh 140h C8h 16 30Eh/782: 320x200x16
10Fh 140h C8h 32 30Fh/783: 320x200x32
111h 280h 1E0h 16 311h/785: 640x480x16
112h 280h 1E0h 32 312h/786: 640x480x32
114h 320h 258h 16 314h/788: 800x600x16
115h 320h 258h 32 315h/789: 800x600x32
117h 400h 300h 16 317h/791: 1024x768x16
118h 400h 300h 32 318h/792: 1024x768x32
11Ah 500h 400h 16 31Ah/794: 1280x1024x16 <---
11Bh 500h 400h 32 31Bh/795: 1280x1024x32
11Dh 280h 190h 16 31Dh/797: 640x400x16
11Eh 280h 190h 32 31Eh/798: 640x400x32
120h 640h 4B0h 8 320h/800: 1600x1200x8
122h 640h 4B0h 16 322h/802: 1600x1200x16
124h 640h 4B0h 32 324h/804: 1600x1200x32
12Eh 140h C8h 8 32Eh/814: 320x200x8
131h 140h F0h 8 331h/817: 320x240x8
133h 140h F0h 16 333h/819: 320x240x16
134h 140h F0h 32 334h/820: 320x240x32
13Bh 578h 41Ah 8 33Bh/827: 1400x1050x8
13Ch 578h 41Ah 16 33Ch/828: 1400x1050x16
13Eh 578h 41Ah 32 33Eh/830: 1400x1050x32
141h 190h 12Ch 8 341h/833: 400x300x8
143h 190h 12Ch 16 343h/835: 400x300x16
144h 190h 12Ch 32 344h/836: 400x300x32
151h 200h 180h 8 351h/849: 512x384x8
153h 200h 180h 16 353h/851: 512x384x16
154h 200h 180h 32 354h/852: 512x384x32

I should try to see if VBE3 is supported, I have found some docs but
I have not yet used those data. my attention is scattered among
countless details now :-/

Also, i could have chosen to simply use 1280x1024 and display
a pixel with 4 real pixels, but i can't in practice.
My algo performs huge quantities of random accesses to the framebuffer
and this already saturates the write combining buffers.
I could maybe double a pixel in a line, but not on consecutive lines
(or the software would slow down the already inefficient CPU).
So at least i need the doublescan feature.

It's getting really exciting...

thanks,
YG (not been here for 8 years or so...)
welcome back ;)
this makes me feel old :-) [but fortunately, I am far from cranky]

wolfgang
YG

.

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