27 January 2010, 01:23 | #41 |
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TNT, if you manage to get the 5V I/O interface up and running, could you please leave a message about what level shifters you are using? I'm prepping for something a bit more... complex than my last project, tentatively looking at the Cyclone EP3C16 (although I'm working with an EP2C20 dev kit), and I'd like to hear about your experience dealing with the 5V/3.3V conversions, especially the latencies you are seeing.
I think it's a bit over-the-top to do this on a board without a ground plane, good luck, you'll definitely need it. Last edited by Shadowfire; 27 January 2010 at 01:35. |
27 January 2010, 07:59 | #42 |
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27 January 2010, 10:00 | #43 | |
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http://www.idt.com/?genId=QS3245 From the datasheet, its data propagation delay is 0.25ns max. I think I also saw Quickswitch series mentioned in some Altera appnotes regarding PCI bus and 5v/3.3v tolerance. I wish I could use a dedicated ground plane, but four layer PCB would be far too expensive for test project like this I am trying to compensate this with copper power/ground polygons wherever possible. |
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27 January 2010, 11:09 | #44 | ||
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(beware: I could have said "graphics+audio card on FPGA". Now, what's worse? ) FPGA Megadrive seems the natural evolution to me too. Good! |
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28 January 2010, 01:20 | #45 |
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Thanks for the link! The quickswitches look very promising.
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04 February 2010, 09:40 | #46 |
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To sum Z3 timings up, this gives ~95ns minimum for simple read cycle. Provided data are read in 32-bits, this results in ~40 Megabytes per second throughput. (And then there are Multiple Transfer Cycles). What happens in real word? Does someone have any Z3 memory board, like this DKB, to benchmark?
Also, what is this 'caching' mentioned in the specification? Does it mean that even if reading byte or word, the card should always present full 32-bit word? |
04 February 2010, 10:25 | #47 |
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04 February 2010, 10:32 | #48 | |
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Can you give the abovementioned test programs a try? The one named 'bustest' probably is able to test selected memory region. |
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04 February 2010, 19:29 | #49 |
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ville9 has published those benchmarks on a1k
http://www.a1k.org/forum/showpost.ph...3&postcount=88 i think pretty understandable also without german knowledge. also there is a whole discussion about a possible zorro ram extention somewhere. |
05 February 2010, 00:18 | #50 |
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Hijacking thread a bit: I noticed people used a Radeon card as memory expansion with some grade of success. A bit faster than chip mem, but hey! It is for free!
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05 February 2010, 00:32 | #51 |
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Hardly free as you need a PCI->Zorro III bridge.
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05 February 2010, 08:21 | #52 | |
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06 February 2010, 04:54 | #53 |
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i think it is that:
http://www.a1k.org/forum/showthread.php?t=15503 i am not able to reread it all atm, the conclusion was afair, it is possible to build such a mem expansion, but it wouldnt be faster than about 10mb/s the forum has english/international section where you might get some help. also in this thread you can find some memory testing software developed and used by hardies on a1k. try the latest versions. you will have probably to replace *.pdf with *.lha or maybe they are just exe's. never used these myself. http://www.a1k.org/forum/showthread....memtest&page=6 |
06 February 2010, 09:24 | #54 | ||
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Well, for timing the maximum theoretical speeds for Zorro III full and multiple cycles, I simply pulled out "The Zorro III Bus Specification by Dave Haynie", flip to "Chapter 5: Timing", and add up the various lengths of different cycle events for each type of cycle. That figure sets the minimum possible cycle time on the bus, in nanoseconds in this case. A cycle transfers 4 bytes, so if you know ns/byte, it's easy to find bytes/ns, and ultimately, megabytes/second. Again, actual Zorro III cycle time is based on the efficiency of the Zorro III bus master and Zorro III bus slave acting together. A 68030 isn't a perfect Zorro III bus master, so you'll find that, for a given memory chip speed, a 68030 will talk to a 68030 memory design faster than a Zorro III memory design. It'll be harder or more expensive to build a Zorro III memory board that'll go 20MB/s with a 68030 (I built one, but it uses expensive SRAM) than it would be to build a native 68030 memory board that'll go 20MB/s with a 68030. That's rather common on I/O buses, and a well designed I/O bus master will be able to drive the Zorro III bus significantly faster than the 68030, or most any CPU, can. -- Dave Haynie Commodore-Amiga (Amiga 3000) Perhaps it will be possible to use higher speed SDRAM (133MHz) or even a DDR /DDR2 memories to achieve minimum access times possible on the bus. Still, even 10mb/s for a Z3 memory seem better than nothing. Quote:
(Psst! Have anyone seen Zetr0 lately?) |
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07 February 2010, 02:32 | #55 |
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ím not quite sure im getting it. zorro ram board made by haynie? ive never heard of a device transferring 20mb/s on zorro3, busmaster or not. not even elbox claims that much for their ide controller, even if it was any close to reality anyway.
but good luck though. the pcb looks shiny indeed! |
07 February 2010, 05:17 | #56 |
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Wasn't Zorro III stillborn?
It seems to me that either replicating the latest Super Buster as a 5V 84-PLCC CPLD would be necessary, given the lack of availability of Zorro III chips these days.
Given that, I've considered putting my time into a replacement Buster that replaces the Zorro bus with PCI. Last edited by aperez; 07 February 2010 at 07:49. Reason: fixed typo |
07 February 2010, 09:44 | #57 | |
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Multiple transfer cycles seem quite promising. I believe most, if not all, designs of the time were based on DRAM with its typical access times of 60-70ns. If you take SRAM with 10-20ns access that'd speed things dramatically. Besides, Zorro RAM board in theory could master the bus by itself. Don't know if it would be able to DMA local (motherboard) memory though, and it most likely would require a software driver of some sort. |
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07 February 2010, 10:37 | #58 | |
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07 February 2010, 11:11 | #59 |
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There are plenty of them around. Commodore reportedly manufactured significantly more Rev9+Rev11 busters than there are A3000/A4000 computers. I think you'd be amazed how may Amiga owners have a Rev9 buster sitting in their drawers cos they upgraded.
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07 February 2010, 17:57 | #60 | |
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