Keyboard with F1–F4 and HELP
The 1200XL had 64 KB RAM and a keyboard with additional F1–F4 and HELP keys. System functions include locking the keyboard and switching character sets, with status shown by L1 and L2 indicators. The computer has two controller ports. Its single cartridge slot is on the left side of the case.
Startup screen and BASIC
Without boot software, the computer displays a colourful Atari logo. ROM contains memory, display, sound and keyboard tests, but no BASIC interpreter. As with the 400 and 800, Atari BASIC requires a cartridge.
A new operating system, without PBI
Changes to the 1200XL operating system caused problems with older programs that called internal ROM routines directly. More RAM did not resolve these incompatibilities.
The rear has SIO, RF and monitor outputs, and a power socket. It lacks the PBI bus found on the later 600XL and 800XL. External disk drives and cassette recorders connect through SIO.