On 16 Nov 98 at 19:03, Linda Brown wrote:

> I have a 16-bit Trident VGA 8900CL video card and was wondering
> what improvments a VESA bus Trident card would give. A friend has
> this VESA video card with one meg of RAM and is willing to give it
> to me if I can use it. Would the preformance be worth the swap?

  All else being equal (and of course it isn't...), your CPU is
currently writing pixels to the screen 16 bits at a time across the
ISA bus at 8-10 MHz.  VLB (VESA Local Bus) will allow it to write 32
bits at a time, on a bus running at 25-33 MHz.  The theoretical
bandwidth between CPU and video buffer would increase by a factor of
5-8 times.
  You shouldn't expect to see this as an overall speed-up, though.
On the one hand, pushing pixels is only part of what most
applications do, and so the amount of time saved and applied to other
processing may be pretty modest.  On the other hand, a 1MB card will
almost certainly expand the range of resolutions and colours
available to you, and may include an accelerator chip which can
offload some common activities from the main CPU altogether.

  [Note that VLB uses a slot connector that looks like the two parts
of an ISA 16-bit connector, plus a third part that looks like a PCI
connector but is in line with the other two.  It was common for 486
motherboards to include 2 or 3 such slots, but you will need to
determine whether *your* machine has them or not.]

David G

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