This repository contains the designs for a Dragon 32/64 multipak interface based closely on the TRS-80 Color Computer multipak system.
The board allows up to four expansion cartridges to be connected instead of the normal single slot.
The original CoCo MultiPak is a poor fit with the Dragon, this design slims down the interface to ensure it will work with the Dragon cartridge port.
The CoCo also includes a -5V rail connection which the Dragon substitutes with an additional +12V rail. Both cartridge pins are unconnected in this design as a precaution
For casual use the +5V supplied by the Dragon PSU should suffice but could become marginal under load. This board includes an independent power supply that can supplement the 5V current supply, or even run a modified Dragon board if additional voltages are not required.
The power board requires either a 12-15V AC input or a 15-18V DC input (polarity of the connector is not important). If 12V is not required (or critical) a lower rated DC power adapter can be used.
By default the 12V rail is rated at 0.5A but the DC-DC converter on the board can easily be swapped for a higher rated compatible component.
A comprehensive set of source definitions for the GAL 16V8 chip at IC13 are available on github: https://github.com/TheLittleEngineers/CoCoDragon-MultiPakInterface-CC-Multi-Pak_Version_1.2/tree/master/PAL_GAL
The GAL programs have been tested for use in a CoCo but not with a Dragon - memory mapping should be compatible so no issue is envisaged
Until testing is completed and the programming conirmed the GAL programs should be treated as untried in this context.