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#1 2014-09-23 15:41:43

jt
Member
From: Bermuda Triangle, NC USA
Registered: 2014-05-21
Posts: 1,470

The MoBo Video vs. PDS vs. NuBus Video Card debate thread.

I don't know about the rest of you, but I think the info available on such choices is sadly lacking in depth and breadth in terms of real world applications. Strengths and weakness of each in the various roles played by these options, where available, need to be discussed and outlined more thoroughly.

Thoughts?


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Last edited by jt (2014-09-23 15:42:22)

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#2 2014-09-23 19:40:50

Eudimorphodon
Member
Registered: 2014-09-02
Posts: 525

Re: The MoBo Video vs. PDS vs. NuBus Video Card debate thread.

Given the bandwidth limitations of NuBus I can imagine for the most part it *should* be a simple equation that most of the time goes something like this:

Dedicated onboard VRAM and/or PDS VRAM > NuBus Card > "shared memory" motherboard video (IIci, PowerMac 6/7/8100)

The if/ands/buts:

A: NuBus cards vary a *lot*, and some of the early low-end ones are probably inferior even to cycle-stealing video solutions like the IIci. The downside of the cycle-stealers is they affect the CPU's access to the memory bus and have the potential of slowing everything down, but they also potentially might have (much) faster fill rates than a cheap card hanging off a 10mhz NuBus and therefore be faster anyway.

B: An application that makes good use of QuickDraw acceleration might be faster on an accelerated NuBus card than on motherboard/PDS VRAM despite probably being stuck with a theoretically lower pixel fill rate. This is where what you're running matters; I would imagine that most games and bitmap graphics applications will do better with dumb-but-fast VRAM, drawing and typesetting programs might do better with acceleration. Also, obviously, it's going to matter how the internal VRAM or "PDS Video" (in most cases other than third-party LC video cards the two are mostly interchangeable) is interfaced on your particular model of Mac; we know how some Macs are convoluted collections of internal bus bridges that allowed Apple to reuse old ASICS so the built-in video in your *particular* mac may be of highly variable quality.

In other words, your mileage will totally vary depending on what you're talking about and what you're doing?


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#3 2014-09-23 20:08:03

ClassicHasClass
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From: Electron Alley
Registered: 2014-05-26
Posts: 1,118
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Re: The MoBo Video vs. PDS vs. NuBus Video Card debate thread.

Yeah, I'm not sure where the debate is.

If I'm QuickDraw-limited, an accelerated card makes more sense even if it's NuBus. If it's just a matter of pushing frames to the framebuffer, PDS or motherboard has a faster bus, and faster still if it has dedicated VRAM. The only trick might be NuBus cards that do bus-mastering, like the 8*24*GC, but that card is rare and temperamental in the wrong system.

In general the debate could only exist, if it exists at all, for an accelerated card. If the card is unaccelerated, I can't think of a situation where the motherboard or PDS video would be slower, even for vampire video systems like the IIci.

trag did a lot of looking into this.


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#4 2014-09-23 20:52:28

jt
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From: Bermuda Triangle, NC USA
Registered: 2014-05-21
Posts: 1,470

Re: The MoBo Video vs. PDS vs. NuBus Video Card debate thread.

Information is probably a better word than debate. That's a reference to what I see as misguided "performance" comparisons in the LEM tech specs and articles. I see too many folks who are newer to the Mac collecting/retro-computing scene asking about getting, or being disappointed with accelerated NuBus VidCards they've already gotten, for increased gaming frame-rates at typically lower resolutions and less demanding bit depth requirements of that kind of application.

ClassicHasClass wrote:

If I'm QuickDraw-limited, an accelerated card makes more sense even if it's NuBus. If it's just a matter of pushing frames to the framebuffer, PDS or motherboard has a faster bus, and faster still if it has dedicated VRAM.

Yep, that's my take as well: NuBus is for pushing gonzo pixels at greater bit depths for Graphic Apps/QuickDraw Redraws and the others are for gaming, more pedestrian requirements a/o economy. An un-accelerated 8bit NuBus VidCard is fine for searching databases or waiting forspreadsheet recalculation for display on a TPD. Photoshop/X-Res would be is at the other end of the TPD spectrum with my favorite Illustration Packages falling somewhere in between. An unaccelerated FPD/TPD Card would have been fine for Medical Imaging, word processing and much of early PageMaker era  DTP as well.

trag did a lot of looking into this.

Since we're a support forum, I figured we should have this thread on the books to tease this kind of info out of the existing woodwork. Information elsewhere seems garbled and shallow.

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#5 2014-09-24 16:00:53

Eudimorphodon
Member
Registered: 2014-09-02
Posts: 525

Re: The MoBo Video vs. PDS vs. NuBus Video Card debate thread.

jt wrote:

Yep, that's my take as well: NuBus is for pushing gonzo pixels at greater bit depths for Graphic Apps/QuickDraw Redraws and the others are for gaming, more pedestrian requirements a/o economy.

Well, again, to be clear it almost certainly has to be an *accelerated* NuBus card to *ever* be faster at "Graphics Apps/QuickDraw Redraws" and I suspect if you're talking about late NuBus machines like Quadras and NuBus PPCs... it would be interesting to see when, if ever, something like a  8*24*GC is faster than the HPV video of a 7100 or 8100. (For that matter I sort of wonder how it *really* stacks up against something like the Quadra 950's built in video. This claims the 8*24*GC is actually only about half as fast as a Quadra 650's built in VRAM, but, granted, that's on a benchmark not a real-world application.) Certainly there may be gray areas where you have no choice but to resort to a Nubus video card over the onboard video even if it's faster; for instance, the onboard video in the Q650/800 is very fast but it only does 16 bit color and tops out at 1152x870x8. The only way you're going to get 24 bit color at high res on those machines is to slap something like a DC 24AC (or its Radius twins) into it, but does anyone have any benchmarks of such a solution? The few hits I can find for benchmarks of a Radius Procolor 24 are frankly not particularly impressive. If you needed to do 24 bit color and could live with 832x624 it wouldn't surprise me at all to find out that swapping your Q800 for a Q950 would be a better investment than the video card, while an 8100 with the 4MB HPV might well be the ultimate "NuBus" Mac when it comes to sheer video oomph despite having to rely on its main CPU in leu of acceleration.

Obviously if you need a NuBus "video card" with specialized hardware to do video editing/capture/whatever that's a different kettle of fish entirely. (EDIT: Also, there were those cards that had DSPs/"Photoshop Accelerators"; that's another gray area and the improvement from such devices isn't likely to show on regular benchmarks, but likewise they're not going to do a thing for programs that don't know how to use them. So... yeah. Whether a NuBus card will *ever* help you is almost completely dependent on what you want to run on it. The only *generic* recommendation you can make really is that if you *don't* have a specific application in mind the Macs with high-speed VRAM-based built-in/PDS video solutions will probably provide the best all-around performance. In other words, if you want a fast NuBus Mac to do "whatever" with, get a high-end Quadra or a 7/8100 with HPV, it'll *probably* be fine.)

Last edited by Eudimorphodon (2014-09-24 16:12:03)


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#6 2014-09-24 16:59:19

jt
Member
From: Bermuda Triangle, NC USA
Registered: 2014-05-21
Posts: 1,470

Re: The MoBo Video vs. PDS vs. NuBus Video Card debate thread.

'OORAH!!!!! Now we're talkin'  .  .  .  wink


.  .  .  doing benchmarking is not something with which I'm not at all familiar, but it's something I'd love to begin doing for this thread.

I've got one of almost every VidCard Radius ever produced, their BiggestBaddestBoard, two of the 24AC they did for Apple, the HPV/2/4, HPV/4/8 and the radius 81/100 in which to test them  .  .  .


.  .  .  with & w/o NewerTech G3 Accelerator in betwixt. smile

I've also got teh Q700, Q950 and a Centris 650 that's badly in need of a Quadra 650 sleeper mod, not to mention a bus-mastering Rocket for testing in the IIcx.






<  .  .  .  entertains thoughts of outing himself as a closet radius Clone & Card collector and Macs in which to play with them, not Macs alone on their own merits  .  .  .  which is probably why he can't say he's got the 8*24*GC for said benchmarking.  hmm >



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Last edited by jt (2014-09-24 17:09:44)

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