Now for the interesting bit!

This is an Acorn 6502 board, one of the component parts of the Acorn System range. On the board is, unsurprisingly, a 6502 processor, a couple of 2114 RAM chips, some other logic chips and a connector on the right hand side for plugging into the rack.

There is a reset switch in the bottom left-hand corner and another connector in the top left-hand corner.

There are two small empty sockets, presumably for more RAM, and two 40-pin sockets, which I can only guess are for VIA chips or suchlike.