an 6809 system with expansion bus

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This is the successor of the Scrumpel8b. It has more RAM and I/O in unused part of the ROM.
In stead of glue logic a gal22v10 is used. All software for Scrumpel8a/b could be used for this Scrumpel with a small modification of the PPORT and ACIA addresses. These need to be changed into $CF20 (PPORT) and $CF00.(ACIA) The gerbers and schematic diagram can be found at github.

This version is expandable and has the following specs:

  1. 48 Kbytes RAM $0000-$BFFF
  2. 16 Kbytes ROM $C000-$FFFF *
  3. 256 Bytes I/O
  4. One serial port 115200 Baud 8N1
  5. On  board 8 bits Parallel I/O port

On the bus two extra addresses for I/O are predecoded.

On board I/O

  • Serial ACIA 68B50 $CF00
  • Paralllel I/O $CF20

*IOSEL is active from $CF00-$CFFF


  • CSAUX $CF60
  • CSPIA $CF40

For other info look at Scrumpel8a/8b project.

  • 1 × CPU 68B09E CPU
  • 1 × 74HCT73 Logic ICs / Flip-Flops, Latches, Registers
  • 1 × ATF22V10 6809addresdecoder
  • 2 × 74HCT32 Electronic Components / Misc. Electronic Components
  • 1 × 74HCT574 Electronic Components / Misc. Electronic Components

View all 23 components

  • 1
    Positioning of the LEDS POWER,RESET,TXD,RXD and RUN

    The square pad on the PCB indicates the Cathode side of the LED. Long leg of LED is the Anode.

View all instructions

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