Just to be REALLY pedantic...
Atari 600XL
Atari 800XL
They were fairly different form factor than the Atari 400/800 and came early/mid 80's, rather than late 70's.
One of the main reasons I bought my first Amiga is because it's a spiritual successor to my beloved Atari 800XL; in my very humble opinion a rather marvellous computer, which for me only had 2 major issues - games were more prevelant for the C64 than the 800XL and the main tape-drive units loaded programs VERY slowly (no 'turbo' load like C64) so games like Gauntlet would take over 20 minutes to load.
Still play "Rescue on Fractalus!" and "Mercenary Escape From Targ" on Atari 800XL emulator every now and then.
