I was too completely taken by it - not least the chance it was a rare Alps mechanical keyboard. Sadly it’s a nasty feeling membrane (at least as far as I can tell).
But it’s an odd one. It came with a PS/2 to 5 pin (?) converter and a floppy disc! The guy who was selling it clearly kept everything together.
The three buttons on the left hand side switch the buttons above it in terms of their function. From function keys to apps and so on - all colour coded icons. The four at the bottom must be media keys. I can’t tell because when I plug it in the 4 key keeps repeating.
I haven’t tried the big blue button at the top - maybe it releases the sodding 4 key…