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Thread: MR-BIOS implementation in a 128KB BIOS image for a Packard Bell PB450 motherboard

  1. #11
    Join Date
    Oct 2017
    Location
    SE Michigan, USA
    Posts
    380

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    Also, the video BIOS is 32KB in size, which is surprising.
    Current retro systems:
    2x Commodore 64 Breadbin 250407 Rev. B and C
    Packard Bell Pack-Mate 28 Plus, aka, the Ultimate Sound Card machine
    iMac G3/600 Graphite, Mac OS X 10.4.11 Tiger, Lubuntu 16.04.3 LTS
    iMac G4/800 Lampshade, Mac OS X 10.4.11 Tiger
    YouTube channel: https://www.youtube.com/c/RetroPCUser

  2. #12

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    There seems to be some kind of unpacking mechanism or at least 1 bit altered. Both images are not directly 1:1 in that big image. This would have been easy...

    I am going to prepare a empty 128k image with the MR-BIOS in it, where usually system BIOSes are located, F000 segment. Do you have a VGA-disable jumper and in best case an extra ISA VGA card?

    Disable the onboard card, as the test-rom has no video bios. Without video card testing also should work. If you have one, burn the ROM, plug in, disabled onboard vga. Turn on. Keyboard lights flash if working BIOS. Either boots without video and without error or beeps for missing video.

    If you have a video card, the rom without video bios works you should be able to boot it and use it. But I doubt everything is that easy...
    If it works, I place the C000.ROM at beginning of image.

    Comes a bit later, short in time now.

    32k is very common for video bioses, also for later ones. I just analysed over 100 video bios fonts from 30-40 video roms in different ages. Most of them are 32k.
    My commodore 386 also has a 128k chip and uses only 96k.

  3. #13
    Join Date
    Oct 2017
    Location
    SE Michigan, USA
    Posts
    380

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    Unfortunately, I don't have any spare ISA video cards in my collection or in my house.

    Also, my network card is able to read the ROM address at C0000, but, I have no idea if I can put the video BIOS programmed to the EEPROM onto the network card itself.
    Current retro systems:
    2x Commodore 64 Breadbin 250407 Rev. B and C
    Packard Bell Pack-Mate 28 Plus, aka, the Ultimate Sound Card machine
    iMac G3/600 Graphite, Mac OS X 10.4.11 Tiger, Lubuntu 16.04.3 LTS
    iMac G4/800 Lampshade, Mac OS X 10.4.11 Tiger
    YouTube channel: https://www.youtube.com/c/RetroPCUser

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