RAM and ROM expansion for the Commodore VIC-20 computer.

If you have a factory machine and you\'ve ever encountered a program that wouldn\'t run because it required more memory, you won\'t take that cartridge out of your VIC-20 :)

Cartridge allows you to:

• Run any program written for the VIC-20.
• Reset the computer without power cycling.
• Embedding up to 4 cartridges with games or programs for instant loading.
• Emulating one cartridge in the RAM.
• No need to open the computer, you just insert the cartridge and configure it using labelled and easily accessible DIP switches.

Note: The cartridge is sold with an empty ROM socket, you need to supply your own ROM / EPROM chip.

Memory organisation

Cartridge is capable of expanding following memory areas:

• RAM1, RAM2, RAM3
• BLK1, BLK2, BLK3 and BLK5.

In total, you will get (up to) 35kB of RAM.

Jumper BLK5 selects how BLK5 block is used: it can be RAM (must be configured using DIP switches) or ROM (the DIP switch positions do not matter). If neither of the positions are selected, BLK5 will be unpopulated in VIC-20.

The DIP switches 1-3 can turn on/off the RAM1/RAM2/RAM3 expansion (1kB each). The DIP switches 4-7 can turn on/off the BLK1, BLK2, BLK3 and BLK5 RAM expansions (8kB each). In case ROM is selected with the jumper BLK5, then DIP switches 9 and 10 can select the 8kB ROM bank from the EEPROM. The DIP switch 8 is not used.

OPTIONAL

The module can also handle a EPROM / EEPROM (through the empty socket) containing cartridge images. You can insert a 28xxx or 27xxx compatible chip. Expansion operates up to four 8kB banks, each containing a cartridge image, which is mapped at $A000-$BFFF (BLK 5). Bank selection is made with two DIP switches as described above. You can use 2864 which will just be 1 bank, 28128 will give 2 banks or 28256 which will give 4 banks. You can also use 27512 with appropriate content layout that will emulate 28256. Please consult datasheets for pinout differences if you are using 27xxx series.