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Thread: Guru on SCSI write (RAM help needed)

  1. #1
    Wallbraker's Avatar
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    Question Guru on SCSI write (RAM help needed) (SOLVED)

    Greetings fellow Amiga lowers! (Solution found, see bottom of this post).

    So I'm having some troubles with my Amiga 2000 Rev 6.2, in it I have a:


    The problem I'm having is that with everything enabled I get Guru 8000 0004 (IIRC) every time I try to write to the SCSI drive.
    Through some experimentation I have found this:
    • Removing the A2630 works!
    • Disable RAM auto-detection work!
    • Making the A2630 only have 2MB RAM does not help.
    • Removing the BigRAM does not help.
    • Removing the IOExpander does not help.
    • Disabling MC68030 caches does not help.
    • I have not tried to insert the card into the first slot Zorro slot.


    Possible solutions:
    • I found this thread (from 1994!) that talks about replacing one of the ICs on the board.
    • Lower the priority of the A2630 RAM so it's not used for DMA.
    • Disable the auto-detection of the A2630 and then add the BigRAM manually.


    The first is not guaranteed to work. The other two are more attractive, if I some how can get only the BigRAM
    to be found I could in buy another extra 4MB for the Impact so I could have a full 8MB in the 24bit DMA space.
    Problem is I do not know how to do either of these, or if it is possible. Which is why I am writing here for help,
    if any of you fellow wonderful Amiga lovers have any ideas, tips or solutions please reply, thanks in advance!

    Solution found:
    Using the Bigram utility that you can download from icomp's wiki, you can add the memory even if the A2360
    RAM auto-config is disabled. Disadvantage is that I'm now 4MB poorer if this had worked out of the box, but
    that is a very small price to pay considering that the Bigram adds about 112MB.

    Cheers, Jakob.
    Last edited by Wallbraker; 16th April 2018 at 18:10. Reason: Solution found! :D

  2. #2
    Dancing with bridgeboards Amibayer! BlindGerMan's Avatar
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    Replace the GVP SCSI with a non-DMA one...
    A2000 2/128/-MB-OS3.9-GVP TekMagic060-Picasso IV+Concierto+PabloII+Paloma-Deneb-Ariadne II-A2386@TI486SLC2
    A2500/30 2/112/6MB-OS3.1-A2630+BigRAM2630-A2091-A2410-A2065-A2286-A2320
    A1200 2/256/-MB-OS3.9-Blizzard 1230IV/SCSI-IDEfix Express-Indi AGA MkIIcr


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    While that might solve my problems, I was hoping for a more soft solution that would also allow me to keep the speed of DMA transfers.

    Cheers, Jakob.

  4. #4
    Dancing with bridgeboards Amibayer! BlindGerMan's Avatar
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    Try to get a GURU ROM for your GVP, maybe it solves your problem...

    But, all DMA controllers for Zorro II have some problems with Turbocards and RAM outside the Zorro II space...
    A2000 2/128/-MB-OS3.9-GVP TekMagic060-Picasso IV+Concierto+PabloII+Paloma-Deneb-Ariadne II-A2386@TI486SLC2
    A2500/30 2/112/6MB-OS3.1-A2630+BigRAM2630-A2091-A2410-A2065-A2286-A2320
    A1200 2/256/-MB-OS3.9-Blizzard 1230IV/SCSI-IDEfix Express-Indi AGA MkIIcr


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    It's a problem of the memory being on the Accelerator card within the 24bit ZorroII space. With or without BigRAM makes no difference.

  6. #6
    Dancing with bridgeboards Amibayer! BlindGerMan's Avatar
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    Defective ram on the A2630?
    A2000 2/128/-MB-OS3.9-GVP TekMagic060-Picasso IV+Concierto+PabloII+Paloma-Deneb-Ariadne II-A2386@TI486SLC2
    A2500/30 2/112/6MB-OS3.1-A2630+BigRAM2630-A2091-A2410-A2065-A2286-A2320
    A1200 2/256/-MB-OS3.9-Blizzard 1230IV/SCSI-IDEfix Express-Indi AGA MkIIcr


  7. #7
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    Solved with the help of icomp's bigram utility, see main post for more details.

  8. #8
    Dancing with bridgeboards Amibayer! BlindGerMan's Avatar
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    What is your hdd speed?
    A2000 2/128/-MB-OS3.9-GVP TekMagic060-Picasso IV+Concierto+PabloII+Paloma-Deneb-Ariadne II-A2386@TI486SLC2
    A2500/30 2/112/6MB-OS3.1-A2630+BigRAM2630-A2091-A2410-A2065-A2286-A2320
    A1200 2/256/-MB-OS3.9-Blizzard 1230IV/SCSI-IDEfix Express-Indi AGA MkIIcr


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    I get 0,7MB/s with the current setup according to Sysinfo, I have done no performance tuning.
    I did see 1MB/s at once point during my experiments, I think that was without any ram from the A2630.

  10. #10
    Jack of Many Trades, Semi-Master of Some thebajaguy's Avatar
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    The GVP FastROM and the GuruROM support DMA to any Zorro II space, and perform all needed copy-up to >24-bit address space. A reminder not to mess with DMA Mask values (should be 0xFFFFFFFE), as the driver handles all of that more efficiently, and internally. Only native C= ROMs in an A2091, and a Microbotics HardFrame (unless proven otherwise) will have problems with DMA >16MB space, and need the Mask hack. Leave MaxTransfer alone, too.

    You should make use of 'CPU Cache FastROM' during startup. However - you have a combination that has a logistical issue or two.

    One problem I will point out is this: You are a likely to have a trip to the Guru if the native OS is merging 16-bit and 32-bit FastRAM into one large block and a special case happens. In this case, the boundary of 005FFFFF/00600000 (assuming 4MB on each), is a bus error waiting to happen. If the 68030 doesn't cleanly longword read (or write) up to 0x005FFFFC->F, then start another longword access on 600000->3, the bus access across two different memory types will cause a hardware bus error to the 68030. You are safe as long as you don't end up using all of the other BigRAM memory, which I assume ends up 1st in the memory list, and don't ever get around to using that last ~4MB+ (16-bit).

    Second - regarding the CPU command. Don't run the FastROM option until the BigRAM is added to the the memory list and is highest priority. If you have a merged memory list like above, the 32-bit A3640 memory (00200000-005FFFFF) merges with the GVP memory (00600000-009FFFFF), and FastROM will end up locating the OS remap in - yes - 16-bit memory on the GVP card at the end of the memory block. It picks the end to have th ebest chance of a useful memory boundary (chunk) for the MMU and to not fragment memory.

    to fix that, you have a few options:

    1) Disable the GVP's 4MB. It's the last 4MB that you would ever want (16-bit) to use, speed wise. FastROM will then grab only 32-bit RAM when invoked (ideally, in this case, the 4MB on the A2630, so as to give you the largest amount later on the BigRAM)
    2) Ensure the BigRAM is in the memory list at a higher priority than the other FastRAM, then call the FastROM option. It will locate in 32-bit RAM there.
    3) Use another MMU-based remap tool (prior to BigRAM addition), and force the 'head' option. By this, going to the head of the memory list for remap memory. The A3640 memory, having merged with the GVP 4MB, will be at the front of that memory pool. Most MMU (like SetCPU and CPU) tools take from the back end of the first or largest memory pool, and that is not best.
    4) (a longshot, but I'll mention it) Get a retargetable graphics card (if this HW is on your shopping list) that sits between the A2630 and the GVP HC8 (and set for 2MB). It will allocate a 2MB chunk of Zorro II space between them, and the OS will never merge them.
    Last edited by thebajaguy; 18th April 2018 at 00:56.
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