SEGA Mega CD Multi-Bios / Which Switchless Code?

Discussion in 'Modding and Hacking - Consoles and Electronics' started by Damn-Deal-Done, Oct 26, 2018.

  1. Bad_Ad84

    Bad_Ad84 The Tick

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    Good response and eases my concerns. Thanks for being mature about it.
     
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  2. Damn-Deal-Done

    Damn-Deal-Done Spirited Member

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    Sega Mega CD BIOS Repair
    Customer's attempt at BIOS swap.
    IMG_7888.JPG
    Customer broke Pins 1, 17, 27, 28, 29, 31, 36, 38, 39.
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    I installed a fresh Japanese Region Free BIOS and jumped the broken pins to vias.
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    Sega Mega CD 2 Fixed.

    PlayStation 1 PSIO Switchboard Installs
    SCPH-5502 PU-18 (My own inc Mayumi 4 install)
    IMG_7979.JPG

    SCPH-1002 PU-8 (Customer)
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    SCPH-5552 PU-18 (Customer. Mod-chip was already installed)
    IMG_8100.JPG

    Sega Game Gear Capacitor Replacements
    #1 My Own (Had no sound and faint image)
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    #2 Customer (No sound and faint image)
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    #3 Customer (No sound and did not switch on)
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    And as a bit of fun. My Sega Mega Drive Switchless Region Mod PCB (Through Hole).
    D'force3000 code. Vishay Capacitor and Resistors and Kingbright LED.
    IMG_7807.JPG
     
    Last edited: Jan 11, 2019
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  3. Damn-Deal-Done

    Damn-Deal-Done Spirited Member

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    Sega Mega CD 2 Region Free BIOS Install
    Original BIOS removed with a desoldering gun, socket and the Japanese region free BIOS installed. I will be moving to hot air removal (with appropriate cover to other components) of original BIOS chips in the not too distant future.

    IMG_8319.JPG

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    I also fixed this customer's drive spindle stop switch which was causing the cogs to grind. I added about 1mm of extra plastic to the switch after which the drive was loading discs in record time. Lens cleaned with 99.9% IPA and an appropriate amount of fresh lithium grease added to the cogs and spindle in appropriate places.

    Sega Mega Drive 2 Switchless Region Mod

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    All trace cuts are done with precision and are a single, straight line. Solder mask is removed from traces under magnification with a scalpel tip. I am thinking whether it is viable to start covering future trace cuts with an overcoat pen.

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    I now use water clear LED's in all consoles with a diffuser (diffusing LED's twice doesn't seem right).

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    Stripboard is stuck down with non corrosive 2mm foam tape. The tape I use has enough tack to hold the board indefinitely but not so strong that it will rip up traces in the event the mod needs removing in the future.

    Nintendo GameCube XenoGC Mod-Chip Install
    Wired install method and a drive pot tweak with a multimeter to read genuine Taiyo Yuden DVD-R media. Upgrading to using an oscilloscope to do real drive calibrations in the not too distant future.

    IMG_8341.JPG

    Mod Kits
    This example SuperCIC kit has Vishay Metal Film Resistors, a SNES appropriate 5mm Water Clear Kingbright LED, and a Vishay Ceramic Capacitor. All components are high quality and from large electronics distributors.
    IMG_8520.JPG
    Chips are kept in their original ESD safe containers, only removed for programming whilst using an ESD strap, and then pushed into ESD safe foam before being placed back into an ESD bag with the other components. These are posted in genuine Jiffy Airkraft padded mailers either same day or within one day.
     
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  4. segasonicfan

    segasonicfan Robust Member

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    Would anyone be so kind as to upload the .bin with all 3 bios files ready for the install (usa default)? Or explain how to modify the bios contents for bank switching?
     
  5. Bad_Ad84

    Bad_Ad84 The Tick

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    Literally just merge them together in the order you want that suits the way you are controlling the address lines.

    Copy /B
     
  6. Damn-Deal-Done

    Damn-Deal-Done Spirited Member

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    Hi. No problem.

    I just updated my reference table.

    The bottom two tables will give you the BIOS order depending on which switchless code you are using. Inverted one is untested but it looks logically sound.

    MultiBIOS-Tables.png

    Borti4938's code has a lot of benefits. It will only change the MultiBIOS during reset but still allows 50hz/60hz switching for the system during play as well as having inverted video and language outputs.

    Creating the MultiBIOS file

    1 - You need to first have the region free BIOS pack.

    2 - Byte swap the three BIOS files. I use GadgetUK164's ByteSwap program.

    3 - Put the three BIOS files you want into a folder and name them in a way that is easy to work with such as.
    jpn.bin
    eur.bin
    usa.bin​

    4 - Copy 1 BIOS file and rename it
    blank.bin​

    5 - Now in this same folder bring up command prompt by typing in the address bar
    cmd​

    6 - In command prompt you can type

    **For Borti4938 and Seb code**
    copy /B usa.bin + eur.bin + jpn.bin + blank.bin multibios.bin​

    **For D'force3000 code**
    copy /B blank.bin + jpn.bin + eur.bin + usa.bin multibios.bin
    7 - Then hit enter.

    multibios.bin will be created into the same folder.

    8 - Check that this is 512Kb in size. If not, redo the command prompt process.
     
    Last edited: Apr 3, 2019
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  7. segasonicfan

    segasonicfan Robust Member

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    dude, i love you
     

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