Computer Museum - Acorn Atom  
Images in the
Computer Museum
are not to scale.
Top of the Page
Top of the Page
Top of the Page
Top of the Page
Top of the Page
In 1979 Acorn produced boards for computer enthusiasts. The following year the company offered the Atom in kit form or ready built.
The Atom came with 2KB of RAM (expandable to 12KB) and a rather individual version of BASIC which unusually but usefully gave the ability to include machine code in a BASIC program. One oddity is the need to tell the Atom if you want a carriage return. On most computers PRINT"HELLO" followed by PRINT"GOODBYE" would place the two words on separate lines.
On the Atom, they appear as HELLOGOODBYE with the cursor at the end of the word. Adding PRINTCHR$13 positions the cursor at the beginning of the same line. Instead, you have to type an apostrophe ' to indicate that you want to start a new line. Failing to finish with an END instruction causes an error message.
The character set is upper-case letters, numbers and punctuation. In common with many computers of the time, there were no lower case letters but the SHIFT key produces letters in inverse video. Block graphics are available, but not from the keyboard. The basic Atom has only one screen resolution (mode 0) but eight others are available when fully expanded.
The power supply at 8 volts and 1.2 amps was only sufficient for the basic computer and even then the two onboard 5 volt regulators became hot. An expanded Atom required a power supply rated at 2.5A or 3A. It was common for people to use a 5 volt psu with the Atom's regulators removed and two links installed. Having done this, the 8 volt power supply would have caused damage to the computer and could not be used.
No serial number. The board is issue 5 with full expansion and floating point.
Atomic Theory and Practice (manual). David Johnson-Davies / Acorn Computers. 10201
Rear connections. Left: Bus, VIA and printer. Right: Video out, DC in, Tape I/O, UHF output.
There are connections for a cassette recorder and a television. It could also be modified to give output to a monitor.
Original Acorn power supply. 8v 1.8A. Computer has been modified with links to bypass 5v regulators.
Substitute power supply. 5v 3A. Tip 5.0 x 2.5 centre positive.
Tape recorder cable (thought to be original). 7-pin DIN to Ear, Mic and Control (do not connect control).
Tape recorder cable (additional). 7-pin DIN to Ear, Mic and Control (do not connect control).
RF (TV) cable. Black.
RF (TV) cable. Grey.
This Atom has a video lead to provide AV or SCART output. It attaches to two pins at PL4 with the black wire at the rear (edge).
On my main pc monitor, the SCART image wobbles but is steady if the aerial lead is also plugged in.
A cassette with INDEX (listing the games and checking loading and display).
BREAKOUT How many bricks can you knock out of the wall before losing the ball? If you destroy one wall, another one will replace it.
HECTIC Catch the bricks before they build themselves up to the same height as your paddle. The more bricks you catch, the higher your score.
MASTERMIND Can you guess the computer's four-digit code in ten attempts? The computer marks each try that you make with a number in each of the B and W columns. The B column indicates the number of correct digits in the correct place, and the W column indicates that number of correct digits wrongly placed.
SKI Ski down the mountain, avoiding the trees, and arrive home safely. If you succeed, you will be given more trees to avoid next time.
SNAKE Guide your snake towards the food. If you eat it, then your snake will grow, along with your score, but if you miss the food, your score will decrease. The game ends when the snake hits itself or the sides.
TRACK Drive your car along a race-track, avoiding the road-sides and oil spills.
SIMON How good is your memory? The computer will assign you a sequence of characters to remember, and will then give them to you one by one, until you either finish the sequence correctly, or make a mistake. The sequence gets longer at each go.
SQUASH Keep the squash ball in play by hitting it with the bat. A point is scored for each bounce, and the game is over after 15 balls have been missed.
MOON Land your Lunar Module safely in the bottom of the crater. If you hit the sides or land with a velocity greater than 20, you will explode!
BOMBS-AWAY The two players have bunkers on opposite sides of the mountain, and take turns in firing shells to destroy each other. The angle and speed for each shell must be carefully chosen for a direct hit on the opponent's bunker, taking into account the height of the mountain and wind velocity.
The original invoice
  Top of the Page