A1240 freezes during boot

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    I am using A1200 with ACA1234 many years without problems. Now I try to connect ACA1240 / 33 MHz, but no success.


    My amiga allways hangs with black or corrupted screen. I never booted to system.

    I tried with installed CF card ( with 68040 libs ), tried with Gotek + installation floppy, and tried without media.

    Amiga allways hangs with black screen, or with picture like this:

    BootErr1

    BootErr2

    BootErr3

    Sometimes picture flashes:

    VideoFlashing

    And even once I received Guru:

    Guru


    I tried to reseat the card many times to different positions

    I measured voltage on floppy connector on ACA1240: 13.63 V, 0, 0, 5.5 V

    led blinks normally : one short flash on beginning, than off

    I tried set jumper to safe position: only difference is that led is continuously blinking


    Original configuration: A1200 rev.2B, ACA1234 + FPU / 50MHz, iComp CF card interface, ROM 3.2.1, AmigaOS 3.2.3, Indivision AGA mk.3, iComp power supply

    Configuration with ACA1240 was the same, only sometimes without CFcard interface and without Gotek


    Now I am run out of ideas, can somebody help?

    One idea more:

    I have installed FPU on motherboard. Can be here some conflict? There is nothing mentioned about it in ACA1240/1260 wiki, but I have to ask...

    Quote from sailor

    I have installed FPU on motherboard. Can be here some conflict?

    Yes, this might be a contributing factor.


    Quote from sailor

    There is nothing mentioned about it in ACA1240/1260 wiki, but I have to ask...

    If you're successful fixing this problem by removing the FPU, we will of course mention it in the Wiki.


    Jens

    Quote from Jens

    If you're successful fixing this problem by removing the FPU, we will of course mention it in the Wiki.


    Jens

    Yesterday I ordered removing tool for FPU. I will post the result during few days.

    Quote from sailor

    And please, can somebody explain me why onboard FPU make such problems?

    The on-board FPU is a peripheral that occupies address space. Upon startup, Kickstart is executing some FPU code to see if there is a bus error - this is a detection method that will also be executed when an accelerator is connected. We may be able to fix this in the FPGA code of the ACA1240/1260, simply by generating the bus error and not accessing the main board for that specific CPU-space access (it's a special access that's indicated by all FCn lines being high).


    Having an FPU on the main board is pretty rare. I'd have to build myself a test case, as I have never seen a use for an FPU - it's mostly been a "for having it"-thing, but didn't speed up any of my use cases.


    Anyway, thanks for reporting back. Yet another thing on the long list of things that we can add to the ACA1240/1260...


    Jens

    Thank you for explanation.
    I think that is not needed to fix this in FPGA code. Too much work for small benefit. For users will be enough to know that there must not be onboard FPU. So please, if you can write this info into ACA1260/1240 Wiki...

    As you said, onboard FPU is very rare. I purchased my A1200 several years ago from Retropassion, and there will be cheap FPU upgrade option ;-)

    It will probably be an easy fix - I have just checked the source code of my 68030 accelerators, and they all don't even route a CPU-access to the main board, which is the most likely reason why your ACA1234 works with the FPU on the main board installed. We should be able to achieve that same behavior in the ACA1240/1260.


    Quote from sailor

    So please, if you can write this info into ACA1260/1240 Wiki...

    While this would be an easy solution, the better way (IMHO) is to not make reading the documentation a requirement. It's always better to "just make it work". We'll look into this and get back to you in this thread, possibly with a test-FPGA core. Here's hope that you have a socket on your A1200 for the FPU, so you can create a test bed easier than I can (not sure if I even have a PLCC-FPU in my collection!).


    Jens

    Quote from Jens

    Here's hope that you have a socket on your A1200 for the FPU, so you can create a test bed easier than I can (not sure if I even have a PLCC-FPU in my collection!).

    Yes of course, I have socket and I will test it.
    Also I prefer to have FPU placed inside A1200 than have it in the box somewhere in basement ;-)

    Will the on-board fpu be usable with ACAs that don't have an fpu of their own? Or will the A1200 fpu just be disabled as well as the 68020 with an ACA123X?

    On-board FPU is just disabled with an accelerator installed. I really don't want to make an address translation for a 50MHz 68030 to access a 14MHz FPU that's wired up to be used by a 68020 (the addresses are slightly different).


    Jens