Jim Brains: Vic-20 Memory expansion / MIDI interface

Es gibt 1 Antwort in diesem Thema, welches 807 mal aufgerufen wurde. Der letzte Beitrag (25. Februar 2023 um 18:50) ist von Mike.

  • Im sure most of you know of Jim Brain in the USA about 5 or more years ago Jim Brain made his own memory expansion cartridge for the Vic-20

    I t hink its called MMC Jim made this available in the USA and its more readily availalble more than 5 years ago and this also contains a Maplin Midi interface

    it just needs a Vic-20 Midi Sequencer. Jims website: Bitte melde dich an, um diesen Link zu sehen.

    This REU uses the onboard 5k up to 34K very nice for the ole Vic-20

    Mainly with the MMC memory expander I dont understand the I guess hex addresses it starts wtih a $xxxxxx would this be just hex for the memory blocks?

    So would I just translate the HEX to decimal, but in the very little documentation on the MMC as far as memory blocks its printed as $XXXXX so I surmize this is HEX and that is the address

    I guess that goes after the POKE statement, then after the comma (in the POKE statement) that has something to do with the memory block.

    This is all I could think of , sorry to say the documentation on this is not easy for a dummy like me to understand, dear me. :/

    I have an old Compute Book that has ML tables and for number conversion for HEX, decimal etc helps some.

    I was really hoping someone else mght have one of these and explain if Im on the right track. :)

  • controlport2 22. Februar 2023 um 06:50

    Hat das Thema freigeschaltet.
  • Mainly with the MMC memory expander I dont understand the I guess hex addresses it starts wtih a $xxxxxx would this be just hex for the memory blocks?

    You might want to check out this thread presumably you yourself started in Denial some years ago: Bitte melde dich an, um diesen Link zu sehen.

    [The cartridge] just needs a Vic-20 Midi Sequencer.

    On go4retro.com, you find the official firmware for VICMIDI at this place:

    Bitte melde dich an, um diesen Link zu sehen.

    You need the two files 'flash4file.prg' and 'ultimem512k.prg'. Assuming you have a SD2IEC-type device handy, put them into the root directory of a SD card, start up your VIC-20, load 'flash4file.prg' and specify 'ultimem512k.prg' as file to flash. This takes some time (on the order of half an hour), so set aside a pot of coffee and watch.


    Both Ultimem and VICMIDI share similar hardware regarding RAM and Flash ROM expansions. There are registers in the cartridge I/O area to specify which parts of that external memory should appear where in the address space of the VIC-20 CPU. RAM expansions of standard size can be activated with a few POKEs (see the list in DenialWIKI). Any advanced use of the registers requires innate knowledge of the VIC-20 hardware which to convey is far beyond the scope of this thread here.