Re: SS20
On Sun, 24 Feb 2002, digihans wrote:
> Craig Ian Dewick wrote:
>
> ...
> There is no way to get usable 24-bit colour on an Sbus-based machine
>
> > *except* in a Sparcstation 20 (or Sparcstation 10-SX) which have a very
> > special framebuffer which needs a removable VSIMM fitted to enable the
> > support hardware on the motherboard. This does not use any Sbus slots
> > though.
>
> Silly question perhaps, but if it is possible to get higher resolution on a SS20,
> by means of some VRAM,
> why are all most all the SS20 i encountered equiped with a cgsix sbus-board???
Because the VSIMM's for Sparc 20's are not just VRAM. They are actually
all of the graphics processing electronics which, together with the 'SX'
memory controller that's on the motherboard, forms the 'cg14' framebuffer.
The VSIMM's do have VRAM on them (either 4 or 8 MB), but there is a
special Analog Devices pallette DAC, and lots of other support electronics
too.
As a result, VSIMM's are not cheap, even today. To buy one of the 501-2481
VSIMM's with 4 MB of RAM, you're looking at US$50 minimum, and the
501-2482 8 MB VSIMM's sell for at least US$100 each (on Ebay). TGX
framebuffers generally sell for a lot less (on Ebay at least).
TGX's are the entry-level framebuffer for SS20's (and also for the early
Ultrasparc machines which do not have PCI or UPA bus support) - the native
24-bit colour support was an option, which at the time (1994/5) was
*extremely* expensive because it was so novel and ground-breaking. The
first Ultra-1 machines never had this btw - it wasn't until the Ultra-1/E
systems came out that they gained UPA bus support and could use the
Creator cards.
Regards,
Craig.
--
Craig Ian Dewick (craig@lios.apana.org.au). http://lios.apana.org.au/~craig
APANA Sydney Regional Co-ordinator. Operator of Jedi (an APANA Sydney POP).
Always striving for a secure long-term future in an insecure short-term world
Have you exported a crypto system today? Do your bit to undermine the NSA.
Reply to: