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Old 12 December 2018, 09:53   #1
Overmann
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Real-world difference between bus speeds

Hi there,

I've been wondering what are the actual difference in performance between the different zorro buses (inkluding fast Zorro II, which is supposedly ZorroIIx2). I've never had a machine with Zorro III but I understand it's bandwith is about the same as VLB, while Zorro II's bandwith is a little less then ISA (which I find surprising).

Does anyone know, or have measured, how the difference in bandwith effect the performance of cards (such as Cybervision 64/3D)? It might be difficult to create an "all-things-being-equal" situation when going from one bus to another as a Zorro II and Zorro III machine will be so different in so many ways, but lets say an A1200/60 with a Zorro II busboard, then in fast-zorro II mode, then an A4000/60 on the Zorro III bus.

Does a Cybervision saturate the Zorro II bus? Would it saturate it in fast-mode as well? Is there really any point in buying an RTG-card for the zorro bus in a machine that could potentially work with a PCI card?

That's just for graphics. I understand that few SCSI cards were made for Zorro III and that the PCI SCSI cards that work with mediator busboards are for some reason capped at about 4mb transfer-rates, but what about other expansion cards like sound/music, videoediting and ethernet?
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Old 12 December 2018, 10:02   #2
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It is noticeable for example when swapping around between more large/colourful RTG screens than can fit into your video card's memory.

There is only one Zorro III network card, it doesn't give much improvement over Zorro III.

The best speed improvements can be had with CPU card local expansions.

Last edited by Jope; 12 December 2018 at 10:09.
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Old 12 December 2018, 10:31   #3
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Wasn't "real life" Zorro II throughput more like 3.5MB/s rather than 5.3MB/s said in that page? At least in practise chunky demos ran more smoothly over AGA than on CV64/3D in Zorro II on my 060 setup.

And the Zorro II bandwidth limitation really shows with games and demos that push raw chunky data on screen and don't use any 2D accelerated functions. For example, playing Napalm in 640x512 mode is quite impossible with Zorro II graphics card, but it flies without any problems over Zorro III or PCI.

Zorro II is somehow acceptable when you use system friendly utilities, and definitely better than AGA for that use, but generally Zorro III or PCI are so much more enjoyable setups.

Sound cards are fine in Zorro II and you get DSP options which is really nice compared to PCI ones.

I guess network cards should be in theory too. Although I don't know if it was Zorro II or just old crappy network card designs, but for me it was like day and night when going from Hydra AmigaNet in Zorro II to Realtek cards in Mediator. Hydra was always a bit unreliable and max transfer speeds were 600kB/s in good weather. 10Mpbs PCI NIC gave steady 1MB/s, and 100Mbps card went over that (but was restricted by CPU then soon). So, in my experience PCI has been much better solution for networking.
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Old 12 December 2018, 12:23   #4
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That's interesting, so for Zorro II graphics are really just productivity-enhancers, and not much use for gaming? Do any of you have any experience with fast-zorroII? I interested to learn if it really results in twice the performance.
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Old 12 December 2018, 13:51   #5
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That's interesting, so for Zorro II graphics are really just productivity-enhancers, and not much use for gaming? Do any of you have any experience with fast-zorroII? I interested to learn if it really results in twice the performance.
Yep, not much use for gaming. Except if you have CV64/3D and want to play about the two 3D accelerated games available :P Descent was OK as 3D accelerated... and some FPS game which never got out of the demo state, have forgotten its name. Can't remember how Payback did... I think I stuck with 2D mode with it for some reason...

I have ZorroIV board (with MediatorZIV), so I'd basically have those double speed Zorro II slots, but I only have the standard CV64/3D which can't take advantage of the better speed. But if it'd work at all how it was advertised, I guess 2x speed for Zorro II would make it noticeably better experience... because the raw speed is what it lacks and if it'd really be close to double speed, I guess I could be quite happy with it. CV64/3D in Zorro II was mostly "if this could be even sligthly faster it wouldn't annoy me that much" experience... it was all the time at the worse side, but wouldn't have needed that much to get on the acceptable side
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Old 12 December 2018, 14:34   #6
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Old 12 December 2018, 16:05   #7
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Quote:
Originally Posted by Overmann View Post
That's interesting, so for Zorro II graphics are really just productivity-enhancers, and not much use for gaming? Do any of you have any experience with fast-zorroII? I interested to learn if it really results in twice the performance.
Even on AGA machines they are near worthless for gaming. You can get a few things like Doom to run on them, but in general it is for productivity apps. That being said, I would never go back to straight AGA Workbench unless I had no choice. My A4000 with a Cybergraphx 64 3D card in incredible - WOrkbench even at 800x600 is fantastic, and it can go much higher than that at blazing speeds.

I had a Picasso 2 in my A2000 (when it was alive), and it worked fine for day to day use. RTG is worth it 100%, just plan on using the standard RBG port for gaming,
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Old 13 December 2018, 10:12   #8
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The thing is, most of the OS-friendly drawing commands are accelerated by passing the instruction directly to the graphics card itself. This takes far less bandwidth than transferring image data, so the limited bandwidth of Zorro-II isn't quite as big an issue as the numbers might make it appear. Using a Picasso-IV in an Amiga 2000 is a far, far better OS experience than AGA, despite AGA having higher bandwidth, purely because the actual pixel generation in many cases doesn't have to traverse the bus at all.

If a game uses the OS routines to draw its graphics (and doesn't simply use it as a frame buffer), then it will still benefit greatly from a Zorro-II RTG card compared to the native chipset.
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Old 13 December 2018, 11:25   #9
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If a game uses the OS routines to draw its graphics (and doesn't simply use it as a frame buffer), then it will still benefit greatly from a Zorro-II RTG card compared to the native chipset.
But can you name any games doing that? I can't... or maybe some small freeware ones running in an OS window... but "real" commercial games are just using it as a dummy frame buffer, and they are affected big time.
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Old 13 December 2018, 11:32   #10
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Yep, true. I'm not familiar with the specific mechanisms of most games. Anything 3D that's not using Warp3D will of course be software rendered, but perhaps there are some 2D games that use the OS blitting routines... Foundation, maybe? I might install that on my 2000 the next time I have some spare time.
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Old 13 December 2018, 19:08   #11
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But can you name any games doing that? I can't... or maybe some small freeware ones running in an OS window... but "real" commercial games are just using it as a dummy frame buffer, and they are affected big time.

I would guess colonization. It surely looks like it is 100% system routines.
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Old 16 December 2018, 20:29   #12
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I've bought a CV3D, so I'll test to see what the benefits of the fastZII mode is at least. I'll post my findings here. I'll also see about overclocking, just for fun, to see if there are benefits also in ZII/fastZII-modes.
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Old 17 December 2018, 07:35   #13
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I've bought a CV3D, so I'll test to see what the benefits of the fastZII mode is at least. I'll post my findings here. I'll also see about overclocking, just for fun, to see if there are benefits also in ZII/fastZII-modes.
But is it a standard CV64/3D or the rare "Z4" version? AFAIK the standard one can't take advantage of the double speed slots found in Z4 boards. Manual tells "This speed will only work with cards that were designed for Fast Z2!". But if you prove me wrong, and you notice speed difference between normal and double speed slots, let us know!

I also have overclocked my CV64/3D to work marginally faster on a Zorro II bus...
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Old 17 December 2018, 07:38   #14
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I would guess colonization. It surely looks like it is 100% system routines.
But does it force on a PAL/NTSC screen? Maybe could be tried with a mode promotor, but I'm little sceptical until someone tries
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Old 17 December 2018, 13:13   #15
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But is it a standard CV64/3D or the rare "Z4" version? AFAIK the standard one can't take advantage of the double speed slots found in Z4 boards. Manual tells "This speed will only work with cards that were designed for Fast Z2!". But if you prove me wrong, and you notice speed difference between normal and double speed slots, let us know!

I also have overclocked my CV64/3D to work marginally faster on a Zorro II bus...
Yes, it is of course the DCE version, that supports fast ZII, so I'll be set to go
How much did you overclock it? Do you know how fast your ram is? I understand 70ns is normal for Phase5 cards, but DCE-cards often have 50ns ram it seems. Do you cool the card?

I'll try colonization while I'm at it, but it will be difficult to gauge any speed improvement as it already runs VERY fast on a stock A1200. WHen I first asked about game-performance I was thinking about RTG-games. I had a PicassoIV back in the day but quickly upgraded to a Voodoo3, and the PIV was left doing scandoubling. :P I don't remember how well it performed on the ZII bus, and how great the improvement was over stock AGA.

What I wanted to know was: Will SCUMMVM, Doom, Shapeshifter etc. run noticably faster on an RTG card on the ZII bus then on AGA, or will the ZII bottleneck be so dramatic that it's niglectible? My guess would be that even on ZII RTG will be dramatically faster.

Correct me if I'm wrong, but mode promotion doesn't result in improved performance. 15 years ago I spent many days trying to get the best possible performance in Sim City 2000. One of the things i tried was mode promotion, but there was no performance increase. I tried it both with my Voodoo 3 and with my Picasso IV.
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Old 17 December 2018, 13:44   #16
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What I wanted to know was: Will SCUMMVM, Doom, Shapeshifter etc. run noticably faster on an RTG card on the ZII bus then on AGA, or will the ZII bottleneck be so dramatic that it's niglectible?
Except for systems with very low CPU power ZII will be slower than properly programmed AGA software for programs working with a chunky buffer.
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Old 17 December 2018, 13:58   #17
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Except for systems with very low CPU power ZII will be slower than properly programmed AGA software for programs working with a chunky buffer.
That is very interesting, and more then a little surprising, but does explain why I get no performance increase when modepro-ing AGA to RTG on my ZII-machine.

EDIT: It will be interesting to see if that is true for Fast ZII as well.

Last edited by Overmann; 17 December 2018 at 14:14.
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Old 17 December 2018, 14:49   #18
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Well, it is an oversimplification because some programs may have a stupid approach and set pixels individually which may lead to working directly with planar graphics which would be very slow. This would be faster with ZII than AGA. However, the important factors here are that AGA has twice the bus speed as ZII due to the 32 bit bus (if I'm not very much mistaken) and that chunky2planar conversion can be hidden pretty much in the copying of the buffer to chip memory (even more so if AGA had as slow a bandwidth as ZII).
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Old 17 December 2018, 15:19   #19
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Yes, it is of course the DCE version, that supports fast ZII, so I'll be set to go
Ok, cool

Quote:
How much did you overclock it? Do you know how fast your ram is? I understand 70ns is normal for Phase5 cards, but DCE-cards often have 50ns ram it seems. Do you cool the card?
I don't remember the details anymore, it was 90s afterall... but when looking at a pic of my card now, I seem to have 66.667 MHz crystal there. Can't remember what it was originally, but I have the phase5 card in any case. Memory chips are MT4C16257DJ-6, so it seems to be 60ns. I don't have any cooling on it.

Quote:
What I wanted to know was: Will SCUMMVM, Doom, Shapeshifter etc. run noticably faster on an RTG card on the ZII bus then on AGA, or will the ZII bottleneck be so dramatic that it's niglectible? My guess would be that even on ZII RTG will be dramatically faster.
As discussed earlier, ZII RTG is slower in these cases, but your double speed ZII will probably be faster.
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Old 31 January 2020, 14:09   #20
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I've done some tests now. I have my A1200 set up with a DCE Cybervision 64/3D and have run sysspeed graphics tests with both ZII and fast ZIII, I have also compared the results to my A3000 030@25 with a Phase5 CV63/3D and the results are a little surprising. ZII and fastZII test exactly the same. So there must be something wrong somewhere, but my ZIV busboard was recently recapped and appears to be working perfectly.
The card in my A1200 test about 5 times faster then the CV64/3D in my A3000. I expect the CPU is bottlenecking the A3000 scores.
My A1200 also test significantly slower then the A2k_060 module in sysspeed (about half the performance), which is strange..

Any thoughts ? :P

EDIT:
I am using the previous version of P96 on both my machines. Is it possible that I need to use a specific driver to use the CV64/3D in fast-ZII mode?

Last edited by Overmann; 31 January 2020 at 14:31.
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