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More on ISA cards / Flashlite 186 SBC

Discussion in 'Embedded' started by Lewin A.R.W. Edwards, Jul 23, 2003.

  1. The discussions here about ISA cards have brought to mind a possible
    solution to a problem I have; how to make a little board that can do
    [email protected]/16bpp video on analog VGA, with a build cost of <=$100.
    Production volumes would be low - 10pc order runs, and probably no
    more than 200-300 total production.

    Specifically, what I'm wondering about is taking a board like the
    Flashlite 186 (www.jkmicro.com/technicalinfo/ti_flashlite186.html) and
    putting an ISA-esque interface on the processor bus port, and using an
    old ISA SVGA card. The reason for picking an x86 is so that I can
    install the card's int 10h BIOS hook and use VESA VBE calls to set the
    desired graphics mode.

    Does this sound feasible? Any obvious, truly stupid thing I've
    forgotten?

    -- Lewin A.R.W. Edwards http://www.zws.com/
    Learn how to build high-performance embedded systems on a budget!
    http://www.amazon.com/exec/obidos/ASIN/0750676094/zws-20
     
    Lewin A.R.W. Edwards, Jul 23, 2003
    #1
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  2. In my time at Arcom Control Systems, we did a lot of work with PC
    peripherals connected to 80186/80188 boards, and we created a product
    (SourceGraph) to drive specific VGA cards.

    You could strike it lucky with a random VGA card, or you could find it
    impossible to get working. It is amazing how much PC-specific stuff is in a
    VGA BIOS - as a board manufacturer, we were able to get access to some BIOS
    source code, so we knew eaxctly how PC-dependant they were. The 80186 is
    PC-code compatible, but key peripherals (timers & interrupt controller) have
    different addresses and functionality, and the memory map probably isn't the
    same as a PC.

    To give one trivial example, we had a VGA board that worked fine in text
    mode, except that all numeric characters 0-9 were corrupt. It turned out
    that it was loading the numeric font (but not the text font!) from the old
    MDA font located in the motherboard BIOS, so we had to fake this at the same
    address in the 80188 memory space.

    I think the reduced production costs could be overwhelmed by increased
    development costs - and who's to say that the ISA card you buy today will
    still be available tomorrow?

    Jeremy Bentham
    Iosoft Ltd.
     
    Jeremy Bentham, Jul 25, 2003
    #2
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  3. Specifically, what I'm wondering about is taking a board like the
    Then you're the gentleman to whom I need to speak :)
    I didn't think of issues like that. Hmm. Well, I still don't think
    this precludes my approach. I don't actually want any of the card's
    BIOS functions - not even text output. I have my own engine for all
    that. The ONLY use for the card's BIOS would be to set the video mode
    to a 640x480x15/16bpp mode. I am assuming that any ISA card I can find
    has its aperture control registers well-enough documented in XFree86's
    sourcecode for me to be able to write my own bank select code (see
    below)

    I've reverse-engineered VGA BIOSes and my experience is that it takes
    1-2 weeks to turn a 32K BIOS into a quality, commented,
    re-assemble-able piece of sourcecode. I don't want to do that.
    Well, I'm sure it won't be. Let me elaborate on my fiendish master
    plan: I want to use the ISA bodge job for market-test purposes. The
    product in question is experimental; we don't know how it will go
    across with consumers. I wouldn't anticipate making more than 25-50 of
    these devices with that bodge. I would think I can source that number
    of fairly similar cards. I was thinking of using, say, Trident
    8900-series cards, which are *largely* intra-family code-compatible
    (certainly the stuff I'd need to program is the same amongst the
    8900C/CL/CX/CXi).

    The EVB for the SED1354 is also an ISA card. So once I have the
    hacked-up version working and shipping, I can get the SED1354's EVB
    working using the same hardware. Once THAT is working, I can make a
    small custom PCB with a 1354 on it, to stick on top of the Flashlite.
    That custom board would be [reasonably] producible, and it also gives
    us a couple of other benefits.
     
    Lewin A.R.W. Edwards, Jul 25, 2003
    #3
  4. Wonder if the VGA related emulator code in the Bochs project would be of any
    use?
     
    DM McGowan II, Jul 26, 2003
    #4
  5. Wonder if the VGA related emulator code in the Bochs project would be of any
    Not sure exactly what use it would be... because whatever chipset I
    use will have special hidden registers required to set those SVGA
    modes. But anyway, I've decided to give this project a try. I'm
    sitting on my hands waiting for the Powers that Be to call JK with the
    company credit card so I can get the EVB.

    It also kind of hinges on how long the "186-ish" CPU on the board will
    take to run my code. I need hands-on testing.
     
    Lewin A.R.W. Edwards, Jul 27, 2003
    #5
  6. Lewin A.R.W. Edwards

    Chris Keegan

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    Trident had chips that are as close as you will get to VGA on a chip. I tore apart a video out (to a monitor) PCMCIA card intended for an HP Jornada. Low and behold there was the Trident chip and very little else. I haven't looked real hard at the Flashlight 186, but if it has any facilities resembling bus signals, interfacing such a chip would be the way to go.
     
    Chris Keegan, Mar 2, 2015
    #6
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