The Speccy used 4116s and 4164s (and later 4464s in the Amstrad versions, except the "+2"). The 4116 was used for lower RAM in 48k version, or all the RAM if yo

The Speccy used 4116s and 4164s (and later 4464s in the Amstrad versions, except the "+2"). The 4116 was used for lower RAM in 48k version, or all the RAM if you had a 16k version. The 4164 was used for upper RAM, and they were the ones that were binned for working upper and lower, and you set a jumper to select the good half to use. In the 128k "toastrack" and grey "+2" it used good versions of the 4164 for all its memory. A neat and typical Sinclair solution to saving a few bob on each unit. --edit to clarify the chips the +2 used