A port expander and ROM card reader for the ZX Spectrum computers.
This is a tested, working project. It is compatible with all 16K & 48K Spectrums (Rubberkey and Spectrum+), Spectrum+ 128K (Toastrack), and Amstrad made Spectrum 128K +2 (Grey). It is NOT compatible with later Amstrad made 128K models due to their expansion ports having a different layout.
There are many 3rd party accessories for the ZX Spectrum computer, both old and new, but the old Speccy has only one expansion port to plug them in. This becomes a problem especially if you are using a modern display adapter like the ZX-VGA-JOY I am using that does not provide a pass thru connector for other interfaces. This is the solution to the problem.
Features:
- One vertical, one horizontal full expansion ports.
- A ROM cartridge slot for all the game or utility cartridges that are designed to work with the Sinclair Interface 2 cartridge port. This port is 100% compatible with original Sinclair 16K game cartridges as well as modern IF2 type cartridges that can contain multiple games.
- Adds a much-needed reset switch if you have a Rubberkey Spectrum, no more unplugging the power jack to reset the computer.
- A power on indicator LED.
- The pin-out of the Spectrum Expansion Port is provided on the silkscreen, this can be very useful for scoping while doing repairs.
- Having a port expansion / replicator has an added benefit of protecting your Speccy's original expansion port contacts. Constant plugging and removing of accessory cards quickly wear down these contacts, sometimes even to the point of rendering it useless.
Parts needed:
- 1K resistor x1 (only needed for the power on LED)
- A LED of any color you choose x1
- 100n capacitor x1 (optional, it is used as a decoupler for the cartridge power pin, the cartriges I tried did not need it, but I provided a place to solder one in if needed)
- 6mm x 6mm SMD tactile switch x1
- 30 pin (2x15) 2.54mm pitch edge connector x1 (for ROM the cartridge)
- 56 pin (2x28) 2.54mm pitch edge connector x2 (one for the vertical expansion, one for the side which plugs into the Speccy)
Notes for assembly:
- All the SMD parts are 1206 package, but the pads can accommodate 0805 package as well. All the parts are clearly indicated on the PCB silkscreen, take care for the LED polarity, it is marked too.
- Get 60 pin (2x30) edge connectors and cut to size from both ends to make a 56 pin connector, the ends should be open to accept any size cards. Same goes for the 30 pin ROM cartridge connector too.
- You'll need to remove the pins (push them out from the soldering side) corresponding to the "orientation key" of all connectors and insert a suitable sized piece of hard plastic etc. to make the "key". Without the orientation key, you can easily destroy your Speccy by inserting cards in reverse or by causing shorts by not correctly aligning the pads. You have been warned!
- NEVER, EVER plug this port expander or anything that goes on it while the Spectrum is powered on. This is the most common mistake that kills the retro computers!
A port expander and ROM card reader for the ZX Spectrum computers.
*PCBWay community is a shared platform and we are not responsible for any design issues.
- Comments(11)
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- Engineer May 11,2024
- (DIY) C64iSTANBUL May 07,2024
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