Gmod2/Ocean/Magic Desk compatible cartridge for Commodore 64 (DIY kit)

A lot of Commodore software is still being written today and nowaday, often designed for cartridges. A bank switched cartridge offers a rather large amount of storage that is instantly available without loading, and directly adressable, which means the Commodore 64 can execute code directly from cartridge. Games can access large amounts of graphics data, which was a lot harder with floppy disks in the golden days of the Commodore 64, let alone tapes. As a result content rich C64 games are being made, which is a new chapter in the already rich software catalog of the Commodore 64.

Popular formats in mass produced C64 cartridges are Magic Desk, Ocean and nowadays, Gmod2. This item is a DIY it that allows you to build these cartridges, but unlike the mass-produced cartrdiges, this cartridge is not designed for mass production purposes, but is rather aimed at hobbyists and developers.

In order to do so, the cartridge has been fully designed from through-hole components, that make it a lot easier to solder at home, and all integrated circuits can be socketed. This includes the flash-ROM, which can be easily removed and programmed in an EPROM programmer and reinstalled. In addition programming in an EPROM programmer, you can program this cartridge inside the C64. Programming the cartridge is possible from any Commodore 64. (The original Gmod2 cartridge has a minimal programming circuit which only allows programming inside the assy 250469 mainboard.)

In order to make the life of developers easier, the cartridge has an on/off switch, which will inhibit the C64 from booting the cartridge. This switch is usefull if the cartridge has been previously programmed and you would like to reprogram it, or just want to get into BASIC for e.g. development or debugging.

This cartridge can be used to run games that are distributed via a digital download on real C64 hardware, but you need to get the files on C64 compatible storage media or use an EPROM programmer.

The actual cartridge formats supported are Gmod2, Magic desk up to 512KB, Ocean 128KB and 512KB. 256KB Ocean cartridges (which use the C64's 16K cart mode) are not supported and neither are 1MB Magic Desk cartridges.

The PCB is wired by default for Ocean and Gmod2 compatibility. An optional jumper J1 allows the user to easily rewire the cartridge in a Magic Desk mode.

A flash utility has been written in order to facilitate easy flashing of the cartridge from the C64. If you have a C64 storage medium that can carry 512KB files, this utility can flash the entire ROM in one sweep. If you happen to have storage media that are not large enough to carry 512KB files, the utility allows you to flash individual flash ROM sectors. For example you can split a 512KB image into 4 files of 128KB and store these on 4 1541 compatible floppy disks. Or you can use 2 256KB files and store these on 2 compatible floppy disks. The utility is flexible and leaves the choice upon you.

The flash utility will be pre-installed in the flash ROM.

The cartridge has two mounting holes, which makes it compatible with a range of available cartridge cases. The following C64 cartridge cases are compatible:

• Individual Computers
• The Future was 8-bit
• Protoparts

More information, including the flash utility and documentation can be found on the DIY Gmod2 cartridge's webpage.

You will receive:

• 1 * cartridge PCB
• 1 * 20 pin DIP socket
• 1 * 16 pin DIP socket
• 1 * 8 pin DIP socket
• 1 * 32 pin PLCC socket
• 1 * toggle switch
• 1 * PNP transistor
• 2 * 10 kΩ resistor
• 1 * diode in DO-35 form factor
  
• 2 * 0.1uF ceramic capacitor
• 1 * 74x273 logic chip
• 1 * 74x139 logic chip
• 1 * 93C86 EEPROM
• 1 * 512KB flash ROM
• 1 * Instruction manual

There is a Commodore 128 version of this cartridge available here.

You will not receive a cartridge case with this item. Would you like to buy the cartridge with a case included? I offer two different cartridge cases, that you can get here:

People interrested to release their games on Gmod2 for mass production should contact Individual Computers. I do not want to become their competitor for mass production cartridges.

The cartridge comes with the flash utility preprogrammed into the ROM. This means that after you solder the parts together, you can plug the cartridge into your Commodore 64 and immedeately start flashing it with the software of your choice.