We had the wobbly RAM packs with the ZX80, only they were white.

A sharp quote about the ZX80: With an unusable keyboard and a quirky BASIC, this machine discouraged millions of people from ever buying another computer.

http://computermuseum.50megs.com/brands/zx80.htm

I loved that machine. Most memorable was that as you used up nearly all of the memory, the number of rows displayed on screen started to reduce.