Display adapter for X11R3 386/ix (cont.)

[Karl Denninger]

In article <MME*QP*@utower.gopas.sub.org> fischer at utower.gopas.sub.org writes:
>
>Hello again,
>
>Scott (Interactive XDevGroup) was kind enough to reply to my 8514/A
>question.
>There are two cards available:
>Western Digital and Paradise. After checking the prices out I have deceided
>to wait some time before I buy one of them. Both are in the ~$1000 range.
>
>Now I have heard that only four cards are supported from Interactive
>in 1024x768 16 colors non-interlaced mode under X-Windows.
>
>a) Genoa Super VGA 5400
>b) Orchid ProDesigner VGA
>c) STB VGA Extra/EM 16
>d) Techmar VGA AD
>
>I'd like to buy one of these.
>Could anyone please mail me his oder hers experiences ? I would prefer
>the fastest of them. When I move a Window on the screen I don't want to
>wait some time as it has happend with my ATI VGA Wonder.

You aren't going to like this answer....

Especially if you want to run 1024x768 in colors (more than 2 planes)

Get a faster machine.  This will help some.  Next, buy a board which has 
an on-board PROCESSOR.  That means something like the Matrox board, or 
the Pixelworks board, etc.  I'm not sure about the 8514/A, it may have one.
You especially want area-fill and line-drawing intristics on the board;
n-gon drawing doesn't hurt.

If you don't do this, you are going to have to wait "some time".  Here's why:

AT buses run at 8Mhz generally.  They also run 8 bits at a time with the VGA
DATA registers.  The >ROM< access may be 16 bit (on some cards), but you 
aren't dealing with the ROMs at all in Unix!  It's all raw device access.

What's the upshot of this?  VGA hardware speed has some bearing on the speed
of the X windows display.  So does the bus speed (if your card can handle 12
Mhz, and you can kick up the bus to it, this will help immensely).  However,
the maniuplations needed to write a full pixel (with color info, etc) to the
VGA adapter are a real mess, and therein lies the bottleneck.  NOTHING will
help this, it's an artifact of the design (which is, IMNSVHO, a big kludge).

Yes, VGA is pretty.  No, it's not fast.  Get dedicated hardware if you're 
real interested in speed.  That ISC does as well as it does is a tribute 
to their coding in the face of adversity.

"X11R3" isn't known as being especially efficient either... R4 is supposed
to be much better, but I haven't had the chance to play with it yet (there's
this little thing called a server that isn't there yet for 386 displays......)

--
Karl Denninger (karl at ddsw1.MCS.COM, <well-connected>!ddsw1!karl)
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