Yea, the 1530 C2N was probably most common
Think the VIC20 had one aswell, alot of machines of the era did
The one and only Commodore machine I owned... the Vic 20.
Switched to an Atari 400 after that and then the Atari ST (still like playing some of the games - emulated though).
And @Massive1 , Grange Hill... The earliest are the best, with Tucker and Co.