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StarDOS Screenshot
StarDOS Screenshot
Technical Info
ROM 16 kbyte
RAM None
Hardware features 1 Button Freeze
Manual PDF: StarDOS Manual
PDF: StarDOS Installation

StarDOS sold by StarPoint Software who also distributed ISEPIC is actually a Kernal ROM replacement in cartridge format. StarDOS was designed by Bryce Nesbitt, Bruce Q.Hammond and Scott M. Blum and became more or less well known. It was however for a long time not on the net or emulated. As a special convenience the customer was asked for the powerup message and his preferred color setup when ordering the cartridge. Wether StarDOS cartridges with personalised ROM were actually shipped is not sure.

The cartridge comes with a clip that must be connected to the PLA of the C64 so it can correctly replace the kernal ROM.

The manual states a copyright of 1986 while adverts from 1985 might hint for several ROM or at least manual versions.

StarDOS Advert
StarDOS Advert


  • Fast serial I/O for all disk operations
  • DOS wedge
  • Function key setup
  • Monitor
  • Disk and file copier
  • Texteditor


Cartridge and 1541 emulation in VICE are working. Some day there will be 1571 support likely :)

stardos.c at the VICE project page explains the StarDOS registers:

    the stardos hardware is kindof perverted. it has two "registers", which
    are nothing more than the IO1 and/or IO2 line connected to a capacitor.
    the caps are then connected to a flipflop. now multiple reads of one of
    the "registers" charges a capacitor, which then when its charged enough
    causes the flipflop to switch. the output of the flipflop then controls
    the GAME line, ie it switches a rom bank at $8000 on or off.

    the original stardos code reads either $de61 or $dfa1 256 times in a loop
    to succesfully switch.

    the second rom bank contains a kernal replacement. the necessary select
    signal comes from a clip that has to be installed inside of the c64.

    the original EPROM has D1 and D2 swapped around.

stardos-exp.c at the VICE project page explains the StarDOS usage with enabled drive component:

    the original EPROM has A10 and A11 swapped around.

    the EPROM contains 16k:

    - 8k additional ROM at $A000-$Bfff
    - 8k patched upper DOS ROM ($E000-$FFFF)

    to test use:

    x64sc -default -drive8type 1541 \
        -cartstar StarDosCartRomV1-4-decoded.bin \
        -dos1541 stardosdriverom.bin \
        -stardos stardos1541romv1-4-a000-decoded.bin \

    stardosdriverom.bin should combine the lower half of the original DOS plus the upper half of the stardos ROM
... adding that as a script to avoid such cmdline creepiness :)

Binaries contains: