EAI Model 180

YEAR: 1970
ITEM: Analog Computer
COMPANY: Electronic Associated Incorporated
COUNTRY: USA
IN OUR COLLECTION: Yes

Manufactured in 1970, the EAI 180 is a hybrid computer, combining analog and digital computation in a single system. Its digital logic is built from first-generation integrated circuits using DTL (diode-transistor logic) technology -- an early step in the transition from discrete transistor computers to modern chip-based electronics.

Problems are programmed on the analog side by physically wiring the calculation circuit with patch cables on the front panel, rather than writing code -- each cable arrangement represents a different mathematical equation. The analog computation runs in a repetitive cycle, or "iterative loop," which can be set to under 10 milliseconds. At that speed, the machine solves its programmed equation more than 100 times per second, fast enough that the changing solution can be displayed as a continuous, flicker-free waveform on an ordinary oscilloscope.

There were several configurations of this computer. Most seem to have been housed in a nice wooden cabinet that had a small drawer at the bottom to store your notes and programming patchcords. However, the wooden cabinets came in at least two versions...one was three units high and a fancier model was five units high. There was a metal cabinet version that was likely a later version.

Some of the variation can be attributed to that fact that these computers were manufactured in at least two places: the US version(s) in EAI at Longbranch, NJ and the Australian version(s) made by EAI's subsidiary, EAI Electronic Associates Pty Ltd in Sydney. The Australian subsidiary evidently subcontracted out the manufacturing to Hawker Siddeley.

Get Our Newsletter