After having the PCBs laying around for a long time, and with a little help, I have finally got the Shadow of the Unicorn Interface to work. The problem was right in front of me all the time and it took a conversation with my friend Russ to realise what was going on.

For those who don’t already know, the Shadow Of The Unicorn interface was meant to revolutionise the ZX Spectrum’s software catalogue by using the 16K of memory space usually inhabited by the Spectrum’s own BASIC Rom allowing larger, better games. Unfortunately, the end product was rather high priced and became the deathknell of it’s publisher, Mikro-Gen (who had earlier success with titles such as Pajamarama and Everyone’s a Wally).

The interface is wired for convenience to enable the original designer to create a one sided PCB. This means that the Address and Data lines were scrambled on the board. This, as I realised, required an obfuscated (Scrambled) ROM image to work correctly. It didn’t help that the ROM images that were available online had been previously unscrambled for use with emulators.

With a little help from the Spectrum community on Facebook and my friend Russ, I obtained a scrambled ROM and the interface sprang to life!

So, after languishing on my shelves for a while, the interface is now working and I have published both the design files and the scrambled ROM image on the Projects page for anyone to make thier own and enjoy the game.