Looking for info on memory

[Nigel Johnson Ham]

I am trying to bring up an 11/23 system in a BA23 box, and the only
memory i have is an obscure Plessey one. The only identification is the
p/n 705920 with dash-100 in white ink. By counting the chips I make it
4MB, but it does not respond. Since it takes the full 22-bit memory
space I can't see how any jumpers would change its accessibility. Does
anybody have a manual?

any help appreciated,

Nigel Johnson