On May 13, 2013, at 11:47 AM, Jeff Walther wrote: > > > On Monday, May 13, 2013 7:31:54 AM UTC-5, Derek Morton wrote: > > True enough... It would seem Robert was able to install the DOS card in his > Centris and everything worked. > > I was lamenting over the inability to use the PPC x100 4MB PDS video card in > a Quadra PDS slot. Whenever I am working with my Quadras I grumble over the > lack of PDS expansion cards. I am perpetually tempted to make one (I even > went out an purchased a large number of the PDS card connectors from a parts > broker) but I never seem to have the time to get around to more than doodling > up a circuit or two. Life always seems to take precedence... And how much > longer before the Quadras start to die? I think the better project would be > to reverse engineer the PALs/GALs used for glue logic... Programmable > devices scare the heck out of me! > > The PPC X100 machines had a 64 bit data bus. The Quedras had a 32 bit data > bus. It would be non-trivial to adapt the X100 PDS video card to work in a > Quadra. My understanding is that the X100 PDS Video card is just a dumb > frame buffer, but that it is very very fast, because it has excellent > bandwidth -- full 64 bit datapath and 32 bit address bus, and they're not > multiplexed (sharing wires) the way they would be if they were PCI or NuBus.
Multiplexing is a pet peeve of mine. The last company I worked at used a variety of microprocessors and micro-controllers and I never enjoyed the HC-11 designs. In fact the higher performance replacements were so tight on their timing that it was virtually impossible to design a system which met the controllers requirements... So we ended up going with one of the many ARM options. I also feel the 65c816 is a poor successor to the 6502 because of the use of multiplexing. Whether the x100 video card could be adapted is an unknown... Perhaps the board would autosize the data bus (thought I doubt it) which would make things much easier. Without some additional design information it would be quite an undertaking though. I was simply wishing Apple had made the video card work with the Quadra too. It could have used the same riser board the DOS card did. Sure it would have reduced the performance of the video when used in a 6100. Sure it would have eliminated it's possible use in the 7100/8100. But it would have made me happy! LOL > f you built a nice Quadra PDS frame buffer card, you could probably extract > the proportional performance out of the Quadras. The last time I checked the > Texas Instruments THS8135 and THS8200 DACs are still available for less than > $10 each. Come up with some video memory, and logic to tie the Quadra bus to > the VRAM, and march the bits out to the DAC, and a declaration ROM and you > could build a pretty nice PDS card for the Quadras. > > BTW, where did you find the compatible Quadra PDS connectors. I have not > looked really hard, but my desultory searches never turned any up. Phoenix Enterprises. I was originally quoted $3.46 each 4 years ago and paid $3.85 around 1-1/2 years ago. Minimum order of $150... It would seem I only purchased 50 where I was remembering 100... So much for my memory. http://www.phoenixent.com/ Search for p/n 8807-140-170LH Their website indicates a stock of 3600 and I have requested a quote for pricing (including minimums and break points). > Jeff Walther > -- -- ----- You received this message because you are a member of the Vintage Macs group. The list FAQ is at http://lowendmac.com/lists/vintagemacs.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to [email protected] To leave this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/vintage-macs Support for older Macs: http://lowendmac.com/services/ --- You received this message because you are subscribed to the Google Groups "Vintage Macs" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/groups/opt_out.
