Thanks to Zoltán Németh from Hungary I can provide a bit more info about this emulator :) I knew these emulators existed but I didn't expect them to be the same size as the EXDOS interface - I was expecting something to plug into the ROM socket!

Videoton are a massive company formed around 1945 who produced everything from rifles and bullets to car stereos, computers and bicycle motors, and apparently either sponsor or have their own football team these days! Over to Zoltán:

"The 'a' Studio is a sofware developer company in Hungary, they are writed many games for Enterprise, at this links, you can see screenshots
(sorry the game details only in hungarian)
Attores
Magicball
Enter_Stack
Enter_Ball
Fire
Eggs of Death
Permo Lift
Reversi Dama Awari

The 'a' Studio developed the software part of the emulator, and the Videoton is developed the hw. The Videoton is one of the largest electronical company in Hungary. It is still alive: http://www.videoton.hu"

With the bus extender and emulator plugged in the EP128 appears as a Speccy and will allow you to do pretty much everything a Speccy could do apart from the FLASH attribute. "'a' Studio" and "Sinclair" is the same length so patching the name from the original Spectrum ROM is easy.

Even the keyboard has been remapped, according to Zoltán: "But the most imported thing: how can find the Spectrum keys? :-) Is available in a help screens, just press Function keys 1-7 when you in Spectrum BASIC mode. You writed, the Sinclair text changed at the startup screen. When I developed the version 4.0 ROM, I changed back to the original text :-)"

There's also increased power consumption involved so if you get your paws on one of these and you're not using an Enterprise PSU remember you'll melt a standard Speccy PSU in about 20 minutes! You need the Speccy +2 PSU to run things properly. I didn't find that out the hard way, oh no. Not during this year's Classic Gaming Expo!

Zoltán has also scanned the original Hungarian manual for the emulator! In case you fancy trying to put your own emulator together here's a couple of scans of the circuit board: front and back. You'll need to provide yer own ROM obviously.