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nubus pds graphics card for 5200?
- Thread starter noglin
- Start date
I believe that model would need an LC-PDS video card, which personally I've found to be rare and few and far between. Plus, since most were aimed at 68030-era machines, I imagine they're probably not much faster than the 5200s native video. I might be wrong though, but hopefully someone with personal experience will chime in.
Are you referring to the mirror cable for the 5200? (I have that one, mostly interested if there are other video cards that would work for it and if they might be faster than the valkyrie chip)
Thanks, the valkyrie chip that came with the 5200 (and 5300/6200/6300) is actually the exact same chip as in the Performa 630, and it is a pretty slow gfx chip.
Yes, that one
I have a Micron Xceed Color Fusion card, it’s based on a Weitek 9000 chip (I used to have a Vesa Local Bus graphics accelerator card for PC called Wizard 9000 that used this exact same chip), and it’s great. I mounted inside a Mystic CC and it works really well - better than the integrated adapter, since it has a lot more VRAM too. Not sure about the speed though, it’s still a measly LCIII PDS interface.
That is very interesting, thanks. Would you consider trying it out it in your 6200?
Based on that the PDS slot on the 5200/6200 connects to PrimeTime II, and according to developer notes, PrimeTime II has buffers, it is quite possible that this is faster than the valkyrie chip (that only has 4 entries in its buffer and rather slow transactions).
Oh sorry to hear that. A pity it would have been very interesting to hear how it performed. I tried look for the card but it seems hard to find and quite expensive.
Not exactly that one but a few Micron Xceed Color30 which were like 500 eur to 1875 eur, most likely folks trying their luck
Hmm on second thought that is a very weird and specific card, meant for the SE/30, but the LC-PDS Micron card is a completely different beast, IMHO similar to the 24AC in concept. It carries 2M of VRAM which is a lot for this class and era of video cards.
according to the manual, the Color Fusion delivers accelerated 24-bit PDS Graphics in 24-bit color, up to 832 x 624 or SVGA 800 x 600, and 16-bit color up to 1152 x 870.
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I would be amazed if any LC-PDS video card would be faster than the integrated graphics in framebuffer performance (unaccelerated). Going from the main 040-type bus to 030 PDS is expensive [slow]. Worse still if it's a LC1 type PDS (like the Color Fusion card) with 96 pins as this will use simulated 16 mhz signalling rather than native bus speed signalling possible on the extended LC3 + PDS.
With acceleration, certain operations would benefit over the integrated graphics but I would doubt that it'd be overall worthwhile and that's putting aside the issues with PPC/68K code intermixing.
With acceleration, certain operations would benefit over the integrated graphics but I would doubt that it'd be overall worthwhile and that's putting aside the issues with PPC/68K code intermixing.
You are probably right, I don't know much about the LC3/LC1 and how the 030 bus works. Are you saying that an LC3+PDS at best runs at 16mhz? THe thing is, from what I understand from the developer notes, it seems PrimeTime II has its own buffers, so if the PrimeTimeII is on the 68040 bus of the 5200, and can store fast to those buffers, and I can then spend cycles doing other things with the ppc chip while the LC3+PDS would get data from those buffers without stalling the cpu, that could beat the valkyrie chip. (Because the valkyrie chip has only 4 entries in its buffer, and it drains those very slowly as video out is being scanned from dram, and during this time the 603 chip has its LSU stalling)
Btw the valkyrie chip is pretty slow as-is, that's why I'm thinking another card might be faster (those in bold below have valkyrie chip, source: https://groups.google.com/g/comp.sys.mac.hardware.misc/c/cc_47GAHYb0/m/zNbbBXRSAIcJ?pli=1)
Speedometer 8 bit Graphics Speed Scores
DESKTOP POWERMACS (bigger number is better)
MODEL RATING
5215/75 .90
6218/75 .78
6230/75 .79
6220/75 .90
IIci "hot rod"(1) 1.44
6100/60 1.76
7200/75 1.97
7100/80 2.05
6100/66(2) 2.13
6100/60(2) 2.17
7200/90 2.33
7100/80(2) 2.37
7500 2.85
7500(2) 3.11
The extended LC3-type PDS offers the option for the PDS card to use the CPU AS/DSACK lines directly at system bus speed for the fastest possible interface in the LC3. But for compataibility, the original 96 pin LC slot portion - the part before the gap - will have simulated 16mhz signalling with appropriate delay introduced so that cards for LC1/2 will still work as they see signals operating in a 16mhz clock domain rather than 25mhz or faster.
Since any model after the LC3(+) will not have a 68030, instead there will be a chip implementing the various signals and features of the 030-type asynchronous bus for IO devices and PDS. All signals will be generated in a simulated clock domain independent from the system bus. The original PDS lines of course simulate 16mhz, I think 16mhz signalling is also used for the LC3 extended lines too.
All the translation delays, synchronization, etc adds up so even the fastest possible 030 bus cycle (2 or 3 simulated-030-clocks) is far slower than anything on the 040 bus. When you take into account that most PDS video boards require more than 3 cycles for basic framebuffer accesses... you can start to see the problem. The raw bandwidth just isn't there. Not an issue for poking bytes over serial, but a big problem for video.
I don't see anything to suggest PrimeTime implements a posted write fifo as the valkyrie does, looks to me that the "buffering" referred to in the developer note just that the 030 data bus coming out of the chip is not directly connected to the system bus.
The other thing to bear in mind is that most LC PDS graphics cards, at least as far as I know, were relatively low-end upgrades for relatively low-end machines. As far as I know, there really weren't any to compare with the relatively high-end cards you got for NuBus or, very occasionally, 040 PDS - it would have been like gilding a pig.
Possibly yes, most PDS video cards are indeed low end, on the other hand the Weitek 9k was a very high end chip especially on the PC market : Chip
Those chips were real fast in the early 90s, while I never had the money for a Mac, I used Autocad and a W9k in my 486Dx2/66 with VLB. I had 1024x768 and remember being happy with the system. But then, I was at school doing Industrial Design, so my exper with these machines was limited. I nust jumped at the chance a few years back to get a W9000 for a Mac….
Those chips were real fast in the early 90s, while I never had the money for a Mac, I used Autocad and a W9k in my 486Dx2/66 with VLB. I had 1024x768 and remember being happy with the system. But then, I was at school doing Industrial Design, so my exper with these machines was limited. I nust jumped at the chance a few years back to get a W9000 for a Mac….
5200 developer notes:
PDS connects to PrimeTimeII with D32, and directly to the 68040 Address bus.
I don't know the 68030 bus protocol but if it is 16mhz and it can transfer in burst mode 32bits per bus cycle, then that is ~60mb/s. If every other cycle it is ~30mb/s
With valkyrie I can write (sustained) ca 17mb/s to the valkyrie chip. So despite 16mhz bus and PrimeTimeII inbetween, it is at least possible it might beat the valkyrie chip?
@zigzagjoe "■ data bus buffers for the internal I/O bus", I think/hope that this implies that the data to the PDS (marked IOD32) has buffers directly on PrimeTimeII so that if CPU writes to it, PrimeTimeII will store in the buffer and immediately signal to the CPU (via the 68040 bus -> 603) that the store completed.
PDS connects to PrimeTimeII with D32, and directly to the 68040 Address bus.
I don't know the 68030 bus protocol but if it is 16mhz and it can transfer in burst mode 32bits per bus cycle, then that is ~60mb/s. If every other cycle it is ~30mb/s
With valkyrie I can write (sustained) ca 17mb/s to the valkyrie chip. So despite 16mhz bus and PrimeTimeII inbetween, it is at least possible it might beat the valkyrie chip?
@zigzagjoe "■ data bus buffers for the internal I/O bus", I think/hope that this implies that the data to the PDS (marked IOD32) has buffers directly on PrimeTimeII so that if CPU writes to it, PrimeTimeII will store in the buffer and immediately signal to the CPU (via the 68040 bus -> 603) that the store completed.
I think you're being wildly optimistic .... remember, this is a slot intended for compatibility with legacy IO cards, not for peak performance.
Again, I do not see anything to suggest that the PrimeTime is implementing a posted write buffer where it is not waiting for completion on writes. Apple is saying buffered because it is electrically buffered by the PrimeTime chip. PrimeTIme certainly has registers as they are required for the 030 dynamic bus sizing implementation, but given that bus errors need to be implemented for the 030 bus it could never assume incoming writes are always valid. There would be no way to propagate a bus error back to the system bus. At best for a write to an 8 bit port it could assume if the first write was valid, then subsequent writes ought to be, but that is all, and no help for a 32 bit port.
There will be additional clock delays on both the 601 to 040 and 040 to 030 for synchronization between different clock domains and bus translation. It's hard to say how quickly 030 bus cycles could be issued back-to-back for that reason without measuring. 030 bursts are highly unlikely to be implemented due to that; it would be a synchronization nightmare and it was never an often used feature for IO. Further, the LC3 connector would be required, not the 96 pin LC connector on that Micron card.
