The Atari 400 (1979). Note the membrane keyboard and single cartridge slot, located beneath the closed cover.

An Atari 800XL
The Atari 8-bit family is a series of 8-bit home computers manufactured from 1979 to 1992.
All are based on the MOS Technology 6502 CPU and were the first home computers designed with custom coprocessor chips.
Over the following decade several versions of the same basic design were released, including the original Atari 400 and 800 and their successors,
the XL and XE series of computers.