CPU: MOS Technology 6502
Speed: 1 MHz
RAM: 2 kB, expandable to 12 kB
ROM: 8 kB, expandable to 12kB with various Acorn and 3rd party ROMs
Sound: 1 channel, integral loudspeaker
Size: 381 x 241 x 64 mm
I/O Ports: Computer Users Tape Standard (CUTS) interface, TV connector, Centronics parallel printer
Storage: Kansas City standard audio cassette interface
Power: 8 volts unregulated DC, providing 5 volts regulated inside the Atom
Note: the Acorn 8V power supply was only rated to 1.5 amps, which was not enough for an atom with fully-populated RAM sockets. The Atom's internal regulators also got uncomfortably hot. Therefore most Atom enthusiasts removed and by-passed the internal regulators and powered their Atoms from an external 5V regulated power supply. 3 amps were typically needed for a fully-populated Atom.
There was no de-facto standard for external 5V connection, but using the same 7-pin DIN connectors as the Atari 800XL allowed the Atari power supply to drive low-power (up to 1.5A) Atoms.
This article is derived from http://en.wikipedia.org/wiki/Acorn_Atom