Page "Acorn Electron" Paragraph 34
from
Wikipedia
The Advanced Plus 3 was very similar to the Acorn Plus 3 but packaged as an ADFS ROM cartridge for the Plus 1 with a disc drive connector at the head.
This made it possible to connect a 5¼ ” floppy disc drive as used by BBC Micro owners or a more common 3½ ” drive.
Page 1 of 1.
1.997 seconds.