Editing Acorn Atom (section)

== Specifications ==

* [[Central processing unit|CPU]]: [[MOS Technology 6502]]
* Speed: 1&nbsp;MHz
* [[Random-access memory|RAM]]: 2&nbsp;KB, expandable to 12&nbsp;KB
* [[Read-only memory|ROM]]: 8&nbsp;KB, expandable to 12&nbsp;KB with various Acorn and 3rd party ROMs
* Sound: 1 channel, integral loudspeaker
* Size: 381×241×64&nbsp;mm
* I/O Ports: Computer Users' Tape Standard ([[Kansas City standard#CUTS|CUTS]]) interface, TV connector, [[Centronics]] parallel printer
* Storage: [[Kansas City standard]] audio cassette interface
* Power: standard 2.1&nbsp;mm power jack connector for 8 volts unregulated DC, providing 5 volts regulated inside the Atom

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 two internal LM7805 regulators (each regulating the +5V for a section of the digital logic independently) also got uncomfortably hot. Therefore, some Atom enthusiasts removed and bypassed the internal regulators and powered their Atoms from an external 5V regulated power supply.{{who|date=August 2020}} Three amps were typically needed for a fully populated Atom.

There has never been a ''de facto'' standard for external 5V connections, but using the same 7-pin [[DIN connector]]s as the Atari 800XL allowed an Atari 5V linear power supply to drive an Atom, so long as the current was less than the Atari PSU rating (1 or 1.5 amps, depending on the model). These are now uncommon, but 5V [[wall-wart]] switch-mode power supplies capable of supplying several amps are a readily and cheaply available alternative.