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Image Courtesy Serge Devidts

IME 86 Electronic Calculator

The Old Calculator Web Museum is happy to announce that it has acquired an IME (Industria Macchine Elettroniche, S.p.A.) Model 86 calculator and associated peripherals for eventual exposition in the museum. Sincere thanks to Serge Devidts for picking up the machine in Germany and arranging for it's shipment to the museum's home in the state of Oregon in the U.S.A.

IME was an Italian company based in Rome. They produced a line of early, yet very capable electronic calculators that were quite competitive in the calculator marketplace, especially in Europe, in the late part of the mid-1960's. Their initial machine, the IME-84, was quite sophisticated as first-generation transistorized calculators go, and the 86, a follow-on design, continued IME's tradition of excellence.

An IME KB-6 Remote Keyboard/Display Unit

The IME-86 calculator was designed to be the centerpiece of a multi-component calculating system. The machine was designed with expansion capabilities in mind. A fairly wide range of options were available for the machine, including remote keyboard/display units (Model KB-6) which could connect to the main calculator through a "hub" that allows up to sixteen remote keyboard/display units to be connected, although only one unit at a time can access the calculator (unlike the Wang 300-series "SE"-model calculators, which could serve four simultaneous users). Also available were external printers, keyboard-only units, external core memory expansion units (MS-306), and programmer units, including the Model DG-308 and DG-408 "Digicorder" devices that transform the IME 86 into a learn-mode programmable calculator.

The IME Model DG-308 Digicorder
Image Courtesy Serge Devidts

The IME 86 is an all-transistor (mostly Germanium PNP) machine, with Nixie tube display. Magnetic core memory provides working memory register storage. The machine carries out the basic four math functions along with automatic square root (which uses memory register four as a scratch register during the calculation). Four accumulator-style memory registers are provided, making the machine particularly useful for more complex operations involving multiple intermediate results. With a capacity of 16 digits, the machine provides plenty of capacity for financial or scientific calculating. The 86 is a fixed-decimal point machine, with two keys ".->" and "<-." which are used to set the decimal point position at any position.

UPDATE 5/9/02

I am happy to report that the IME 86S calculator, DG-308 Digicorder programmer, MS-306 memory expansion unit, and a KB-1 keyboard unit (part of the MS-306 memory expansion unit) have safely made their way from Germany, to Belgium, and then on to the museum. (Thanks again, Serge!)

Upon arrival, it was found that the calculator unit had a fault surrounding digit entry. The symptom was that digit entry would cause the numeral pressed to briefly flicker into existence in the least-significant digit of the display, then the digit would revert back to '0'. It seemed like perhaps the core memory was not 'remembering' the digit properly. After reverse-engineering part of the core memory subsystem, the problem was traced to two faulty transistors in the core memory drivers. These were replaced, and the machine is now fully functional. The DG-308 programmer was later connected up, and seems to be functional. I have been successful in loading simple programs and running them, though it is clear there are features of this device (including its built-in punched card reader) that need further investigation. The MS-306 memory expansion unit powers up, but at this point it isn't clear how to operate it. The KB-1 unit which connects to the MS-306 causes digits to be entered into the calculator when numeral keys are pressed, but that's about all I can get it to do. I am hoping that over time I will be able to figure out how it is supposed to operate, or better yet, perhaps I will find some documentation.

UPDATE 9/22/03

Time constraints, issues relating to moving, some electronic problems with the machine, and waiting for historical information on IME have all contributed to limiting progress on documenting the machine for the museum. An exhibit will be delayed until some of the issues can be worked out.