I've been given one of these old fella's which dosen't work and I wont to get it operational (it's a hobbie).
On the bottom of the unit theres a small square door held in place with a screw, Inside it looks like there's supposed to be a chip of some kind can some please tell me what it is for and if you can still buy them or not?

I've been given one of these old fella's which dosen't work and I wont to get it operational (it's a hobbie).
On the bottom of the unit theres a small square door held in place with a screw, Inside it looks like there's supposed to be a chip of some kind can some please tell me what it is for and if you can still buy them or not?

Most likely it's for adding additional RAM (memory chips).. or some other optional device.

The slot IS for additional RAM. For older machines, it's hard to find, but I find alot of older stuff on eBay, if you're into that.