TwinPort Jr.: Cartridge port doubler for PCjr.

Not enough ports? Make two ports out of one using this!

  •  TwinPort JR (assembled)
  •  TwinPort JR (assembled)
  •  TwinPort JR (assembled)
  •  Example use
  •  Example use
  •  DIY Kit version
  •  DIY Kit version


The PCjr has two cartridge ports, but in some cases it is not enough!

For instance, our resetJR module uses one port. But then, what if you also wish to use our SDCart JR card reader and an accelerator cartridge?

Another use case is for software development, for instance to use a ZIF socket on an EPROM cartridge. Or even hardware development. For instance, when you need to probe a signals on your custom cartridge-based peripheral it is much easier with the board fully outside the PCjr slot.

If one of the above situations apply to you, or for any other reason why you need more than two ports, consider the TwinPort Jr.! It should be functionally equivalent to the Synectics Siamese Adapter.

  • Beveled card edge connector
  • Dual 36-pin card slots wired in parallel.
  • Available in ready-to use (assembled) and DIY versions (not assembled)

When using multiple cartridges, make sure there are no bus conflicts by reviewing which address range/chip selects are used by your cartridges before use!

We recommend turning the power off before inserting/removing cartridges.

Be careful not to short the exposed pins with anything (rings, etc) when in use.



在庫あり : 通常3日以内発送
品名TwinPort Jr., DIY Kit version (non-assembled)
product picture
品名TwinPort Jr., pre-assembled version (ready to use)
product picture




Insert this small module into one of the cartridge slots to easily add a power led and reset button to your system.



This cartridge PCB lets you use MMC/SD cards as a removable storage medium for your PCjr and can even replace a hard drive!



PCB for making your own IBM PCjr computer cartridge.