I cant remember exact years but we had a 400 first,I think in '1982 probably when the XL's were about to be released because I remember them being mega expensive.
Later we upgraded the 400 to 32k.
I remember using the 400 with a 1050 before we upgraded to an 800XL.
The 1050 we had modded by a guy in a dodgy part of town with a lazer mod (probably a clone)
This was handy to run all the backups from the guys at Marconi Radar that my Dad knew 🏴☠️️
I had never heard of Percom, Astra,Indus etc until I joined up here many many years later.