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Facit 1111 Portable Electronic Calculator

Updated 1/13/2023

The Facit 1111, other than cabinet and color-scheme differences, is an OEM (Original Equipment Manufacturer) version of the Sharp EL-8. The EL-8, introduced in January, 1971, was the first easily portable battery-powered electronic calculator with a truly usable runtime on battery power. Noted Swedish mechanical calculator manufacturer Facit AB, along with its wholly-owned subsidiary, Addo-X, had an OEM relationship with Sharp Corporation. This agreement provided Facit with right to purchase the electronics from Sharp and package it in their own cabinetry and keyboard key caps, marketing the resulting calculators under the Facit and Addo-X brand-names. The Addo-X machine was designated the model 9364, and was packaged in the same cabinet as the Facit 1111.

Profile View of Facit 1111

The exhibited Facit 1111 was manufactured in February of 1971, making it a very early production version of any of the Sharp, Facit or Addo machines. The exhibited calculator was given to me as a birthday gift by my parents (who had to save for some time to be able to purchase this machine from a local business-machine store) on my 13th birthday in late 1972. At a retail price of $345 1972 dollars (roughly equivalent to $2350 in 2022), it was a rather extravagant birthday gift, but my parents were willing to make such a sacrifice because I was very interested in math, and this was a way that they could support my interest. I was the only kid in school to have a calculator at that time. The batteries lasted long enough to make it through an entire math class without a recharge! Some kids even offered to give me their lunch money to borrow it to help with their math homework. Some of the teachers at school were quite threatened by me bringing the calculator to school. In those days calculators were thought to be tools only to be used by adults who already knew their basic math skills, and use of a calculator by children would cause them to not learn how to do math themselves. At one point I was summoned to the office and asked by the principal to leave the calculator at home. The reason given was that the presence of the calculator in the classroom was too disruptive, and even though the principal knew I was skilled in performing the math by hand, the other children in the classroom were too distracted by the calculator. Fortunately, the attitudes about such things have have changed, such that calculators are an now an important part of the math and science curriculums in schools, and are considered a valuable learning tool.

Unique Itron display tube used in the Facit 1111

The Facit 1111 is a basic four function, eight digit floating point calculator. It operates exactly the same as the Sharp EL-8. It uses individual tube-type vacuum fluorescent displays, with a unique eight-segment pattern, causing the digits to look more hand written. The most unique digit is the 0, which is half-height, and takes some getting used to, but, in lieu of leading zero suppression, does make it easier for the user to ignore insignificant leading zeroes.

The Autonetics/Rockwell-fabricated LSI IC chip set in the Facit 1111

The insides of the Facit 1111 are identical to the Sharp EL-8. The brain of the calculator utilizes four Metal-Oxide Semiconductor (MOS) Large Scale Integration (LSI) integrated circuits in ceramic 42-pin zig-zag pin layout packages, which were actually made by Sharp in Japan. The SHARP marking on the chips is indicatative of the chips being manufactured by Sharp. Initially, the LSI ICs and the special clock driver chip were fabricated and packaged entirely by the Autonetics division of North American Rockwell in the US, as at the time, Sharp did not have the capability to produced such advanced integrated circuits. As part of the agreement Sharp had with Autonetics, Sharp would receive training, documentation and assistance in building out the production capabilities to make these advanced ICs, with the goal being that Sharp would be able to produce its own LSI chips without having to import them from the US. Later versions of the EL-8/EL-8M/Facit 1111 and Addo 9364 transitioned to using chips manufactured in Japan by Sharp.

The LSI chips are mounted on a high quality phenolic, solder-masked & silkscreened, double-sided printed circuit board that appears as if was a stretch for the printed circuit board technology of the time, with tightly- packed, narrow circuit traces that can sneak between the closely spaced pins of the LSI chips. It is clear that Sharp's circuit board technology was stretched to make this circuit board, but it was executed very nicely. The board also contains two capacitors (one electrolytic, one ceramic disc), one discrete resistor (56K Ohm), and a hybrid module that contains sixteeen 250K Ohm resistors. The resistor pack has a date code of the 8th week 1971 (71.08, the last full week in February, 1971), and the circuit board has a date stamp of 46.7.20. The circuit board date code is represented in what is called a Showa date. Showa dates use a form of YY.MM.DD, with YY indicating the year of Japanese Emperor Hirohito's reign over Japan (with year one being 1926), MM indicating the month of the year, and DD indicating the day of the month. Therefore, the code indicates year 46 of Emperor Hirohito's Reign (1926+46-1=1971), month of 7 (July), and day of 20. It appears that this date stamp was the date when the assembled circuit board passed its final quality assurance testing/inspection, which was Tuesday, July 20, 1971. That date might seem out of place to a shrewd reader of this exhibit, but more on that later. It seems at that point, the circuit board was placed into production inventory for eventual placement in a calculator.

A few months after receiving the calculator, it failed, with the machine displaying random segments on the display and no response to the keyboard. I was devastated. The calculator had to be sent to a service depot in Burlingame, Califoria. It was determined that the the main calculator board was faulty, and it was replaced under warranty. It took three weeks for the calculator to come back, and I felt lost without it. This explains why the dating on the calculator circuit board is later than the manufacturing date of the calculator, with the replacement board produced in the latter part of 1971.

The LSI chip set used in the EL-8 and it's OEM copies are the same in function as the chips used in Sharp's breakthrough QT-8D, the first successful mass-market calculator to utilize MOS/LSI integrated circuit technology. In order to provide for a more useful amount of runtime on battery power, some redesign of the chips was done to cut the power consumption of the chip set by nearly half from the chips used in the QT-8B, which was a follow-on to the Sharp QT-8D that added a sizable rechargeable battery pack to the QT-8D, and provided a docking station that the QT-8B snapped into for charging as well as providing a way to run the calculator on AC power.

Though the QT-8B was portable and could operate on battery power, it was rather large and a bit heavy for easy portability, especially since the charger dock usually needed to be carried with it as a means to charge up depleted batteries. Along with that, the battery-powered runtime of the QT-8B was rather short, limiting its effectiveness for field use.

In fact, Sharp was disappointed with the sales of the QT-8D and QT-8B calculators, feeling that their smaller size and use of space-age LSI circuitry would be a huge draw for customers, but the bulkiness and weight of the machines, along wih the limited battery runtime of the QT-8B did not seem to favorable to potential buyers, who in many cases opted to buy portable calculators from other manufacturers, such as SCM's Marchant I, Sanyo's ICC-0081 and ICC-82D, Canon's Pocketronic portable printing calculator, Nippon Calculating Machine Company's Busicom LE-120A "Handy LE" (first LED, 4xAA Battery-Power), and Brother's Pro-Cal 408. These and a few others came to market at around the same time or not long after the Sharp QT-8B was introduced, and certainly did dilute the market for Sharp's machines to a degree, as many of them were smaller, lighter, and would run on battery power for longer. Some models also did not require an external charger module to charge or run on AC power, providing a detachable cord could be connected to the calculator to charge it as well as to operated it on mains power. The Sharp EL-8 was the result of an intense engineering effort by Sharp and Autonetics to reduce the power consumption of the LSI chipset to by half.

The display and display driving circuitry reside on another circuit board that plugs into the edge-connector-based backplane. The keyboard unit also connects into the backplane. The Facit uses an easily-replaceable Nickel Cadmium (NiCd) 7.2V battery pack. Beneath the battery pack is another circuit board that contains the power supply circuitry that generates the -25V power supply for the chips and display system from the battery pack. The 1111 has an external AC power supply/charger module (indentical to that provided with the Sharp EL-8) that plugs into the calculator for operation from AC power, or for charging the NiCd battery pack.

View with back cover removed

The calculator minimizes real-estate on the keyboard by having a dual-function multiply/divide key. To multiply, the multiplicand is entered, followed by pressing the [X÷] key, then the multiplier is entered. To complete the calculator, the [+=] key is pressed. To divide, the dividend is entered, the [X÷] key depressed, then the divisor is entered and [-=] key is pressed to perform the division.

Text and images Copyright ©1997-2023, Rick Bensene.

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