• C64 Motherboard Refresh

    From Daniel@1:340/7 to All on Thu May 7 08:42:00 2020
    Adrian's digital basement released a video today showing off a number of things including newly manufactured C64 motherboard pcb's.

    I looked it up and found the site. Sold out of the UK. I'm ordering one.

    https://www.tindie.com/products/bobsbits/sixtyclone-commodore-64-replica-pcbs/

    Features below are from the website. Impressive that they even sell teh cap kits and provide sources for replacement chips.

    These are replica Printed Circuit Boards (PCBs) derived from the Commodore 64 8-bit computer.

    The boards were created to allow Commodore 64 computers that had damaged or faulty PCBs to be successfully repaired. This can be achieved by moving all components from an original board to the replica board, or even replace some parts with more modern alternatives.

    We currently have 3 x replica board models available:

    Assembly #250407
    Assembly #250466
    Assembly #250469

    Assembly #250407

    This board design was one of the earliest used by Commodore. It requires 8 x 8KB RAM ICs and many logic ICs as well as the commodore custom ICs:

    6526 CIAs (2)
    Basic, Kernal and Char ROMs
    6510 Processor
    PLA
    6581 SID
    VIC II Video Controller

    Assembly #250466

    This board was the last to be produced by Commodore that used the original set of custom ICs:

    6526 CIAs (2)
    Basic, Kernal and Char ROMs
    6510 Processor
    PLA
    6581 SID
    VIC II Video Controller

    This board tends to be more reliable due to requiring fewer logic ICs, but some parts can be harder or more expensive to obtain (e.g MOS 8701 IC). The board also uses 2 x 32KB RAM ICs as opposed to more common 8 x 8KB ICs.
    Assembly #250469 "Short Board"

    This board was one the last to be produced by Commodore and was quite a change from the 2 earlier boards above. The entire board is a lot more narrow, giving it the "Short Board" nickname. The custom ICs used in this board are:

    6526 CIAs (2)
    Basic ROM
    Combined Kernal & Char ROM
    8500 (6510 compatible) Processor
    Custom 64-Pin PLA
    SID (Later 8580 version!)
    VIC II Video Controller (Later 8565 version!)

    Some parts can be harder or more expensive to obtain (e.g MOS 8701, Custom PLA etc.). The board also uses 2 x 32KB RAM ICs.
    Other Information

    Over the past 30+ years, there have been many boards that have become damaged for various reasons such as poor storage conditions etc.

    The replica boards are of the same dimensions of the originals and can therefore be used as a direct replacement to the original PCBs.

    Some improvements/modifications were made:

    Improved silkscreen, adding more descriptive connector labels, IC names and better placed component labels
    Manufactured using modern PCB manufacturing techniques and materials.
    Separate holes for R38 and it's accompanying capacitor so they no longer need to be stacked on the 250407 board.

    Prototype boards were tested with diagnostic software and harnesses to ensure no issues were encountered.

    A "Bill of Materials" community editable spreadsheet has been created to help locating replacements parts: Click here to access.
    Optional Extras

    Some replacement components can be purchased along with the boards:

    Resistor Packs, containing all required resistors for the specific model of board selected. All resistors are high quality metal film resistors. Electrolytic Capacitor Packs, containing all required Electrolytic capacitors for the specific model of board selected. All Electrolytic Capacitors are high quality branded products.
    Resistor Networks, containing the resistor network components for the specific model of board selected.
    Other available component packs will be added as they become available.

    Daniel Traechin
    ... Visit me at gopher://gcpp.world
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