X11 expertise on ancient HW sought... (4-plane visual (overlay) via X-server on MS-WIndows)

Tomasz Rola rtomek at ceti.pl
Wed Jun 10 16:27:48 CDT 2015

On Thu, Jun 04, 2015 at 08:24:31PM +0200, IMAP List Administration wrote:
> [also posted to comp.graphics.x today]
> Hello Folks,
> I'm trying to get an application that currently uses a local display
> on an ancient DEC Alpha workstation with a (for the time)
> mid-to-high-end graphics controller (ZLX-E2) to instead use an
> X-server running under MS-Windows.
> The application is complaining that it cannot find a "4/5-bit
> visual". It almost certainly wants to use this visual for an
> overlay, as the application displays moving objects superimposed on
> a map.
> I have tested VcXsrv, Reflection-X, Exceed (with 3D option), X-Win32
> and even the ancient DEC Pathworks X-server eXcursion with no
> success. I'm working on getting an evaluation copy of PTC's MKSTools
> X/Server. Of the X-servers I've tested, Exceed seems to offer the
> most configuration parameters.
> I'm not even sure the Quadro 400 can handle 4bpp "visuals", or
> whatever MS-Windows calls them. In fact, I wonder if any modern
> hardware offers 4bpp capability. On my Linux box with a GeForce GT
> 430 I don't have any 4-plane visuals, and xprop doesn't mention any
> overlays either.

Pardon my ignorance, I'm definitely not an expert and after sending
this msg I am going to hide and pretend to be dead. However, I cannot
see if you tried running your app on Linux-based X server. This might
be easy to do and does not even require installing Linux. When I want
to test some new hardware, I usually download GRML onto pendrive and
boot from it. It's small, really, like half of CD-ROM. And it has
relatively new X-server, plus few other things like compiler and Open
Office, but in this case it doesn't matter.


In case you go this way, it may make sense to read some manpages and
experiment with options to server - different color depths, screen
size (a.k.a. resolution). Perhaps there are some options to the client
(DEC app) too, and maybe there is a match.

BTW, is the problem related to just one app your customer wants? Can
you run xterm from your DEC and display it on new X-server?

I'm not sure what GPU has got to do with 4 bits per pixel stuff. I
have always thought the problem with bpp is only when graphics chip
doesn't have enough memory to handle, say, 1024x768 pixels, each
containing 4 bits (16 colors mode), i.e. it has less than 384kB of
RAM. And in such case, every app could have its own colormap, which
caused display to blink in a psychodelic way. The last time I even
bothered was probably when I added 1MB of video memory to empty socket
on S3 video card, which allowed me to run X in 800x600 24bpp
mode... about 17 years ago. So I think it would be a bit strange to
have such problem today.

Anyway, I'm definitely not an expert. Consider my questions as
controls or noise, I have no idea what they are. Now I will run and

Tomasz Rola

** A C programmer asked whether computer had Buddha's nature.      **
** As the answer, master did "rm -rif" on the programmer's home    **
** directory. And then the C programmer became enlightened...      **
**                                                                 **
** Tomasz Rola          mailto:tomasz_rola at bigfoot.com             **

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