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  • Re: Reconfiguring C1's FPGAs as CPU?

    From =?ISO-8859-15?Q?Michael_J=2E_Sch=FClke?=@news0306@mjschuelke.de to comp.sys.cbm on Tuesday, July 01, 2003 15:04:47
    From Newsgroup: comp.sys.cbm

    Lorenzo J. Lucchini wrote:

    I was wondering if it could be possible to configure one or both the Commodore One's FPGAs so that they act as the main CPU.

    AFAIK, yes, that's possible. It is certainly possible with the smaller
    FPGA as...

    1) There might not be nearly enough space on them for that

    ... the 6502 that controls the start-up actually runs on that, so there
    is more than enough space.

    2) They might not have access to the buses a CPU requires (RAM,
    namely)

    They have.

    3) I've read someone that the smaller FPGA is reprogrammable, which
    seemed to imply that the other is not

    No, they are both reprogrammable, and are in fact programmed at every start-up. However, they can only be reprogrammed as a whole, and as
    (AFAIK) the larger FPGA acts as a memory, video and sound controller in
    what is planned to be the "C-1 native mode", reprogramming it on the fly
    could be a bit tricky.

    Regards,
    Michael
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  • From White Flame \(aka David Holz\)@whiteflame52@y.a.h.o.o.com to comp.sys.cbm on Tuesday, July 01, 2003 06:59:45
    From Newsgroup: comp.sys.cbm

    "Lorenzo J. Lucchini" <ljlbox@tiscalinet.it> wrote in message news:1f24a1b2.0307010443.7bae7000@posting.google.com...
    I was wondering if it could be possible to configure one or both the Commodore One's FPGAs so that they act as the main CPU.
    The problems I can see with this are:
    1) There might not be nearly enough space on them for that

    The little 30k FPGA has a modified 6502, plus IDE, plus the video driver,
    plus a bunch of other stuff in it, so I'd think you could stuff a fairly featureful CPU into the 100k. :)

    2) They might not have access to the buses a CPU requires (RAM,
    namely)

    AFAIR, both do.

    3) I've read someone that the smaller FPGA is reprogrammable, which
    seemed to imply that the other is not

    The 30k has a default config from a ROM on the motherboard. This then loads
    up your custom 100k config from the boot device. After boot, you can
    reprogram the 30k at will, so both can have custom code on it. As far as hot-programming the 100k during runtime, I think you need to defer that
    through the 30k, though it's quite doable.

    --
    White Flame (aka David Holz)
    http://www.white-flame.com/
    (spamblock in effect)



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  • From ljlbox@ljlbox@tiscalinet.it (Lorenzo J. Lucchini) to comp.sys.cbm on Tuesday, July 01, 2003 15:36:28
    From Newsgroup: comp.sys.cbm

    Michael J. Schülke <news0306@mjschuelke.de> wrote in message news:<MPG.196ba545a9915fc798973d@News.CIS.DFN.DE>...
    Lorenzo J. Lucchini wrote:

    [snip]

    No, they are both reprogrammable, and are in fact programmed at every start-up. However, they can only be reprogrammed as a whole, and as
    (AFAIK) the larger FPGA acts as a memory, video and sound controller in
    what is planned to be the "C-1 native mode", reprogramming it on the fly could be a bit tricky.

    First, thank you and David Holz for your replies.

    What I was thinking of is about doing the closest thing to "designing
    my own computer" without messing with actual hardware.
    So I don't really care much about losing the built-in memory access,
    video and audio functionalities, as long as I can design my own
    instead (which are probably going to be much simpler, like no audio
    and simplicistic video).

    But I wonder: I've read in more than one place that the C1 has a CPU
    slot where you'll be able to plug various CPU modules (6502, Z80,
    etc.). Why do it this way if you can just write the bitstream on an
    FPGA?
    Or have I got it all wrong?

    Lastly, how big of a CPU do you think you could squeeze in the FPGAs
    while mantaining basic (video, memory) I/O capabilities?

    by LjL
    ljlbox@tiscalinet.it
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  • From White Flame \(aka David Holz\)@whiteflame52@y.a.h.o.o.com to comp.sys.cbm on Wednesday, July 02, 2003 00:46:35
    From Newsgroup: comp.sys.cbm

    "Lorenzo J. Lucchini" <ljlbox@tiscalinet.it> wrote in message news:1f24a1b2.0307011436.3ce93053@posting.google.com...
    What I was thinking of is about doing the closest thing to "designing
    my own computer" without messing with actual hardware.
    So I don't really care much about losing the built-in memory access,
    video and audio functionalities, as long as I can design my own
    instead (which are probably going to be much simpler, like no audio
    and simplicistic video).

    I think a lot of us want it for that purpose, too. :)

    But I wonder: I've read in more than one place that the C1 has a CPU
    slot where you'll be able to plug various CPU modules (6502, Z80,
    etc.). Why do it this way if you can just write the bitstream on an
    FPGA?

    Because then you have a lot more room on the FPGAs to do other fun stuff.
    And you don't have to design your own CPU.

    Lastly, how big of a CPU do you think you could squeeze in the FPGAs
    while mantaining basic (video, memory) I/O capabilities?

    No idea. You'd just have to start designing the VHDL and see how many gates
    it compiles into. Things like non-iterative multiplies and divides would probably take up a large portion of the CPU.

    --
    White Flame (aka David Holz)
    http://www.white-flame.com/
    (spamblock in effect)


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  • From wildstar@wildstar128@hotmail.com to comp.sys.cbm on Tuesday, July 08, 2003 04:18:39
    From Newsgroup: comp.sys.cbm

    ljlbox@tiscalinet.it (Lorenzo J. Lucchini) wrote in news:1f24a1b2.0307010443.7bae7000@posting.google.com:

    I was wondering if it could be possible to configure one or both the Commodore One's FPGAs so that they act as the main CPU.
    The problems I can see with this are:
    1) There might not be nearly enough space on them for that
    2) They might not have access to the buses a CPU requires (RAM,
    namely)
    3) I've read someone that the smaller FPGA is reprogrammable, which
    seemed to imply that the other is not

    Is any of these correct? And, am I missing other possible problems?
    As far as point 1 is concerned, I'm not thinking about a *big* CPU.

    by LjL
    ljlbox@tiscalinet.it


    Yes, actually during the early startup process and mode selection. The
    BootROM written by MV is apparently written to the 6502 variant developed
    by Jeri Ellsworth. (Nicknamed the 65JE02 or 65J02 aka Drive CPU). This is loaded into the 30K LE FPGA chip. From my understanding, it also operates
    the IDE drives and the Sound. This CPU is the master CPU until selections
    are made and then the 65c816 ("factory" socketed) or whatever CPU is in
    the CPU slot via a CPU card (if the 65c816 is unsocketed from the 44 pin socket) will become the main CPU. This is a CPU switch over process.

    I would assume both FPGAs can be the main CPU whenever it has control
    over the bus. In theory, it may be possible but I doubt in parellel in
    anyway.

    I can not answer with 100% confidence whether the 100K LE FPGA is
    configured to be reprogrammable but I think it is.

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  • From wildstar@wildstar128@hotmail.com to comp.sys.cbm on Tuesday, July 08, 2003 04:31:28
    From Newsgroup: comp.sys.cbm

    "White Flame \(aka David Holz\)" <whiteflame52@y.a.h.o.o.com> wrote in news:bdu233$n1a$1@barad-dur.nas.com:


    I think a lot of us want it for that purpose, too. :)


    Because then you have a lot more room on the FPGAs to do other fun
    stuff. And you don't have to design your own CPU.


    No idea. You'd just have to start designing the VHDL and see how many
    gates it compiles into. Things like non-iterative multiplies and
    divides would probably take up a large portion of the CPU.

    Without video, depends on design but the CPU slot can also have an FPGA
    on a card designed for the bus. If I recall correctly, if you had the
    money, you can purchase yourself a 1M LEs FPGA chip and solder it to a
    PCB board designed for the CPU slot. If you did that, you can save
    yourself alot of LEs on the onboard FPGAs to do other fun video and sound stuff and leave the CPU stuff to a dedicated FPGA chip. This way, you can
    be free to do alot of other fun stuff as well. Depending on design, one
    may even have a local bus of some sort for some really fun stuff. I'll
    leave it that.

    FPGAs can be had for $30-40. The more LEs, the higher the price. So if
    you want to build your own CPUs on an FPGA, check out Altera (for
    example) and you can get your very own and design yourself a PCB board.

    I think it will be fun. Anyway guys, have fun.


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