@richard.faulkner Had a quick trawl in the garage & found the packaging for it (but not the item itself)...richard.faulkner wrote: Sat May 02, 2020 9:56 am That would be great! Even if I know what it was called so I could put a watch on eBay that would be great. The midex has a few extra ports which will come in handy.
It's from Best Electronics & is labelled as "ST/MEGA 40 PIN CARTRIDGE PORT EXTENSION CABLE PRINTED CIRCUIT BOARD SET" - it comprises a small PCB to plug into the cartridge port & a heard & the other board was the PCB with the equivalent cartridge port on the ST.
If I get chance to dig a bit deeper for the actual boards I will & will post some more info.
Of course, it's entirely possible that they may still have some stock of these...if you can get an answer from Brad - I'm pretty sure I got it from him at one of the shows around 20 years ago