This page shows a selection of interesting portable calculators from some of the less-well-known manufacturers from the early to mid-1970s. Please refer to the separate brands listings for machines from Canon, Casio, Sanyo, Sharp, and others, or use the Full Index if seaching for a particular make or model.
Click on the photos for larger illustrations, or follow the links for further details.
Triumph from Nuremburg and Adler from Frankfurt were two long-established German companies that built (mainly) bicycles, cars, and typewriters from the 1890s. Both companies transitioned to office equipment after WWII, and were combined as Triumph-Adler in 1957. T-A has had several different owners, including Grundig, Volkswagen, Olivetti, and Litton Industries. It is curently part of Kyocera, and is still active in Europe in IT printing and services.
Adler 60
Adler Type EC-60, S/N 65050387
Functions: ASMD
Technology: MOS-LSI (Omron HD 32163P)
Display: 6 digits, vacuum fluorescent tube
Dimensions: 100W x 157D x 43H, weight 360g including batteries.
Manufactured: Made in Japan for T-A Vertriebs GmbH, Nürnberg,
Germany, 1973
The Adler EC-60 is a very basic four-function portable calculator from 1973. It was supplied with a soft slip case with a carrying strap, but is much too large to be called a "pocket" calculator.
The EC-60 uses a single-chip Hitachi HD-32163P processor (made by
Omron) and a single-ended 6-digit fluorescent display tube from ISE.
The display digits are only about 4.5mm high. Power consumption is
quite high at about 120mA (720mW) from four AA batteries or an
external AC adapter. The batteries and input socket are held in a
removable carrier which clips in to the end of the case, suggesting
that an alternative module with rechargeable NiCad batteries may have
been available.
EC-60 rear view with battery carrier.
EC-60 circuit board.
Adler Lady EC-20L
Adler "Lady", Type EC-20L, S/N 68.855.385.11
Functions: ASMD, percent
Technology: MOS-LSI (Sharp LI-2006)
Display: 8 digits, vacuum fluorescent tube
Dimensions: 63W x 93D x 23H, weight 125g including batteries.
Manufactured: Made in Japan for T-A Vertriebs GmbH, Nürnberg,
Germany, 1975.
The colourful EC-20L "Lady" is a compact 8-digit calculator designed to be carried in a lady's handbag. To avoid discrimination, a black-and-white "Sir" version was also made.
The single-chip LI-2006 processor is branded "Sharp", but is
probably a Rockwell chip packaged by Sharp. The floating-point
display uses a double-ended 9-digit fluorescent tube showing 8
calculation digits plus sign/error. Power consumption is about
55mA (250mW) from three AAA batteries.
Adler "Lady" internal view..
Adler 84F
Adler Financial Calculator, Model 84F, Type EC-27, S/N 68.828.401
Functions: ASMD, percent, financial calculations
Technology: MOS-LSI (Rockwell A4561PB)
Display: 8 digits, vacuum fluorescent module
Dimensions: 75W x 120D x 20H, weight 200g.
Manufactured: Made in Japan for T-A Vertriebs GmbH, Nürnberg,
Germany, 1975
The Adler 84F is a compact pocket calculator for business and financial applications. In Algebraic mode it performs only ASMD and percentage calculations, with all results rounded to 2 decimal places. In Business mode it performs pre-programmed financial calculations involving prices, payments, and interest, with assistance from the Enter and Compute keys.
The calculator has a black plastic casing with a wrap-around aluminium sleeve covering the sides and the back. The sleeve slides upwards to reveal the nameplate and the battery compartment. The processor is a single-chip Rockwell A4561PB dated April 1975, on a circuit board labelled "GICO Japan". The display is a 9-digit vacuum fluorescent panel, with the leftmost digit reserved for minus and error indicators. Power consumption is about 400mW from four AAA cells.
The Adler 84F is based on the range of Anita pocket calculators
developed in 1972 by Rockwell and the
Bell Punch Company and sold
under the Triumph, Adler, and Anita brands. The calculators appear
to have been made in Japan, to a British design, for sale by a
German company - but both the British and German companies were
owned by Americans. Triumph-Adler was owned by Litton Industries
from 1968, and Sumlock Anita was owned by Rockwell from 1973.
Further details of the connections between these companies can
be found on Nigel Tout's
Anita Calculators web site.
Adler 108T scientific calculator
Adler scientific calculator, Model 108T, Type EC-28, S/N 68.687.704
Functions: ASMD, scientific functions
Technology: MOS-LSI (Rockwell LA4802PA)
Display: 8+2 digits, 12-digit vacuum fluorescent module
Dimensions: 85W x 147D x 25H, weight 320g.
Manufactured: Made in Japan for T-A Vertriebs GmbH, Nürnberg,
Germany, 1975
The Adler 108T is a portable "scientific" calculator from 1975. It provides trig functions and their inverses in degrees or radians, powers and roots, natural and base-10 logarithms, and one memory register with direct memory artithmetic. The calculator uses algebraic entry with two levels of parentheses, but all of the scientific and memory functions require the use of an "F-key" prefix. An "inverse F-key" is provided for the trig functions. Results greater than 8 digits or less than 1 are displayed in scientific notation.
The calculator is built in the same style as the 84F above, but is
considerably larger. The processor is a single-chip Rockwell LA4802PA
dated October 1975, on a circuit board labelled "GICO Japan". The display
uses a 12-digit fluorescent panel (Itron FG125A2) to show results in
"8+2" format, with the remaining two positions reserved for signs and
memory/error indicators. Results from the scientific functions are
produced quickly (well under a second), but are only shown to six
figures. The circuitry draws 50-60mA (about 300-350mW) from four
disposable AA batteries or an external AC adaptor.
Adler 108T internal view.
Adler 108T circuit board detail.
Litronix Inc was established in the USA in 1970 to manufacture opto-electronic components based on the new light-emitting diodes (LEDs). The company established a manufacturing plant in Malaysia, and became a major supplier of LED components and displays. In the mid-1970s Litronix produced a range of calculators and LED watches under their own name, primarily to showcase their displays. Litronix has been part of Siemens since the 1980s.
Litronix 1100 LED calculator
Litronix LED calculator, Model 1100, S/N 337064
Functions: ASMD, fixed decimal point
Technology: MOS-LSI (single chip)
Display: 8 digits, miniature LED modules
Dimensions: 75W x 150D x 20H, weight 180g.
Manufactured: Assembled in Malaysia by Litronix Inc,
Cupertino, CA, 1974
The Model 1100 is a revised version of Litronix's first "Checkmate" calculator, which was part of the 1970s craze for "check-book balancing" applications. Like its predecessor, the Model 1100 is a very basic four-function calculator with a fixed-decimal system. Inputs and results are restricted to either 6.2 or 4.4 format (ie, nnnnnn.dd or nnnn.dddd), according to the setting of the Decimals switch. However, the calculator always operates internally to 12 figures. If the result exceeds the capacity of the selected format, the calculator shows the least significant digits and lights an overflow indicator. The result can then be divided manually by 1000 (or other convenient factor) to retrieve the higher digits. If the result exceeds 12 figures the display shows all zeros, and the caclulator must be cleared in order to continue.
The circuit board carries a 40-pin processor chip identified only by a hand-written paper label. (There are no markings under the label). There are two 16-pin chips adjacent to the keyboard and display, also unidentified. The LED display uses three miniature 3-digit 7-segment modules, with a single overflow LED at the left-hand side. The display modules have built-in magnifying lenses, and have a fairly limited viewing angle. The keyboard is a "click" module from Texas Instruments, with two small slider switches for power and decimal selection. The main circuit board is hand-soldered, and the calculator is assembled with clips, glue, and heat-staked plastic pins.
The calculator draws 40 to 60mA (270mW max) from three AA
batteries. A small encapsulated power supply (top, in PCB view)
provides the additional voltages needed for the MOS processor.
Litronix 1100 circuit board.
Rockwell was founded in the USA in 1919 as a manufacturing company, and eventually became a major industrial conglomerate with very wide interests. Its micro-electronics division purchased several smaller calculator companies (including Unicom and Anita), and played a large part in driving the "calculator wars" of the early 1970s. Rockwell abandoned the calculator business only a few years later in favour of new Space Shuttle and military contracts.
Rockwell Model 203
Rockwell Metric Conversion Calculator, Model 203, S/N 318644
Functions: ASMD, metric conversions, 2 memory registers
Technology: MOS-LSI (Rockwell A4004PC)
Display: 8 digits, VFD module (ISE DP89A)
Dimensions: 85W x 155D x 40H, weight 200g (300g with alkaline batery)
Manufactured: Unicom Systems, Sunnyvale, CA, 1974.
The Rockwell 203 is one of a series of calculators made by Unicom Systems in California in the early 70s. Unicom was purchased by Rockwell, and the calculators were sold under the Rockwell name. (Both names appear on the nameplate). The 203 has the appearance of a large "pocket" calculator, although the fold-out stand and angled keytops make it equally suitable for desktop use. It was supplied with a soft carrying case and a 36-page instruction booklet (which does not fit in the case).
The keyboard is arranged with 20 keys (in 4 rows and 5 columns) and 4 slider switches. All the keys have dual functions. The calculator performs normal ASMD calculations to 8 digits, with a choice of 2 decimal places or a floating-point display. There are two memory registers selected with M 1 or M 2. The M key also acts as a prefix to select the memory "second functions" marked beside the +, -, =, and C keys.
The conversion functions use pre-programmed constants and the CONV key to convert distance, volume, weight, and temperature between the Imperial and metric systems. (Switches select US volumes or nautical miles). Operation is very simple: enter a number, press CONV, press the "From" unit and then the "To" unit. There is provision to enter a user-defined conversion factor using the CONV/K key, and to enter Imperial fractions (eg 4-5/16 inches) using the A/O key. In this case, entering 4 A/O 5 A/O 16 A/O CONV Inch MM shows the reult as 109.5375mm.
The circuit board
uses a Rockwell A4004PC processor dated September 1974, with an 8-digit
vacuum fluorescent display panel from ISE (Japan). The DP89A VFD panel
is an early metal-backed version, from before the all-glass construction
was developed. Two 5mm red LEDs provide overflow and minus indications.
The calculator has an internal plastic chassis to support the keyboard
and the CPU board, but the boards are only attached to the chassis with
painter's masking tape. A forest of hand-soldered wires runs from the
CPU board to the keyboard and the four slider switches. The calculator
draws about 70mA (420mW max) from four AA cells, and has provision for
rechargeable batteries with an external charger.
Rockwell 203 keyboard and display.
Rockwell 203 circuit board.
Rockwell Model 18R
Rockwell LED Calculator, Model 18R, S/N 354123
Functions: ASMD, percent, 1 memory
Technology: MOS-LSI (Rockwell B5000CC)
Display: 8 digits, NS LED module
Dimensions: 75W x 155D x 22H, weight 160g.
Manufactured: Assembled in Mexico for Rockwell International,
Anaheim, CA, 1976
The 18R is typical of a family of LED-display calculators (8R, 10R, 20R, 30R, etc) produced by Rockwell under their own name in the mid-1970s, shortly before they abandoned the calculator business. The machine illustrated was assembled in Mexico using "US and foreign parts". Others are known to have been assembled in England at the former Sumlock Anita factory (purchased by Rockwell in 1973).
The circuit board
uses a Rockwell B5000CC processor and an 8-digit LED display panel
from National Semiconductor. One digit position is sacrificed if a minus
sign is required - zero minus 12345678 gives an error (all decimal points
lit) as there is nowhere to show the minus sign. The modular keyboard
plugs into the connectors around the right and bottom edges of the
circuit board. The calculator draws only 7 to 30mA (270mW max) from a
standard 9V battery mounted in the area above the display.
Rockwell 18R circuit board.
The National Semiconductor Corporation (usually abbreviated to NatSemi or NS) was a major developer and manufacturer of analog, digital, and microprocessor integrated circuits from the 1960s onwards. It advanced the "calculator wars" for a brief period in the mid-70s with a range of low-cost LED-display calculators. NS continued until 2011, when it was purchased by Texas Instruments.
Novus Mathematician Model 4510
Novus Mathematician, Model 4510, S/N 179491
Functions: ASMD, scientific functions
Technology: MOS-LSI (National MM5760N)
Display: 8 digits, LED module
Dimensions: 75W x 150D x 32H, weight 170g.
Manufactured: National Semiconductor, USA, 1975
The Model 4510 "Mathematician" is one of a family of popular low-cost calculators manufactured under the Novus brand by National Semiconductor Corporation (NS) in the mid-1970s.
The Mathematician provides trig, log, and power functions, and a single memory register. The "mathematician" label possibly comes from a function to accumulate squares for statistical calculations. Data entry uses the postfix (reverse Polish) system, but the calculator does not use scientific notation. Numbers larger than 8 figures result in overflow, which lights all the zeroes and decimal points. Function calculations are slow, with a busy display and significant errors in the 7th (or sometimes even the 6th) figure. The calculator was no match for the Hewlett-Packard 35, but it was only a fraction of the price, and was still a hundred times more accurate than the slide rule.
The circuitry of the Novus 4510 uses only three components - a
MM5760N processor, a DM8864 LED driver, and a 9-digit LED display
module, all made by NS themselves. The calculator draws 20-65mA
(600mW max) from a standard 9V battery. A power-saving mode changes
the display to all decimal points after about 30 seconds of
inactivity.
Novus 4510 circuit board.
National Semiconductor, Model 200
National Semiconductor, Model 200, S/N 0889-077
Functions: ASMD, percent, square root, 1 memory
Technology: MOS-LSI (National MM57134)
Display: 8 digits, vacuum fluorescent module
Dimensions: 70W x 135D x 15H, weight 160g.
Manufactured: Made in Taiwan for National Semiconductor, USA, 1976
The Model 200 is a basic four-function calculator with percent and square root functions and a single memory register. The casing is only 15mm thick, or 20mm when enclosed in its imitation-leather wallet. The calculator uses a fluorescent rather than LED display, and carries National Semiconductor's own name rather than the "Novus" brand of their consumer division.
The circuitry consists only of a MM57134 processor, and a modular power supply to drive the Futaba 9-ST-10 display. The calculator draws about 110-130mA (600mW max) from three AAA batteries or an external AC adaptor.
The calculators in this section were most likely all made in the same factory, but they carry a variety of brand names. They all use the same plastic case, the same "Best Choice 4055" modular power supply, and very similar circuit board designs. The only clue as to their origin is a "Made in Taiwan" on one of the nameplates.
Qualitron 1438 Conversion Calculator
Qualitron Conversion Calculator, Model 1438, S/N 539155
Functions: ASMD, metric conversions, 2 memory registers
Technology: MOS-LSI (Rockwell A4004PC)
Display: 8 digits, vacuum fluorescent module
Dimensions: 75W x 145D x 35H, weight 250g.
Manufactured: Qualitron, Taiwan, 1975
The Qualitron 1438 is a basic four-function calculator with a range of pre-programmed conversion factors for distance, weight, volume, and temperature. It uses the same processor as the Rockwell 203 above, and operates in exactly the same manner (except that there is no fixed/floating decimal switch - all results are shown in floating point).
The Qualitron is smaller than the Rockwell, but has a clearer 5-row 4-column keyboard layout. The A/O key is marked /, but the memory "second functions" on +, -, =, and C (which are obvious after explanation) are not marked at all. The CONV-K key (for entering a custom conversion) is labelled CONV-ENT.
The circuit board shows the Rockwell A4004PC processor (dated January 1975), an Itron FG95A 9-digit all-glass fluorescent display panel, and a "Best Choice" modular power supply, with only about a dozen discrete components. The leftmost digit of the display is reserved for overflow and error indications, replacing the separate LED indicators in the Rockwell. Power consumption is the same 70mA (420mW) from four disposable AA batteries or an external 6V adaptor.
The same machine with different nameplates was also sold as the
"Castle Model 1438 Conversion Calculator".
Castle 1438 conversion calculator.
Qualitron and Castle rear nameplates.
Qualitron 1438 circuit board.
Prinztronic SC4001M scientific calculator
Prinztronic Scientific Calculator, Model SC4001M , S/N 928647
Functions: ASMD, scientific functions
Technology: MOS-LSI (GI CF-596)
Display: 8 digits, vacuum fluorescent module
Dimensions: 75W x 145D x 35H, weight 250g.
Manufactured: Made in Taiwan, 1975
Prinztronic was the house brand of a British company which sold re-branded calculators from a variety of manufacturers. This Model SC4001M scientific calculator is obviously from the same factory as the Qualitron/Castle shown above.
The scientific functions include exponential notaion, trig
functions and their inverses in degrees or radians, natural logs,
square roots and reciprocals. There is a single memory register.
The calculator operates to 8 significant figures, but displays only
5+2 digits in scientific notation. The trig and log functions are
quite slow, and are only accurate to 5 figures. The
circuit board
is similar to the Qualitron above, but with a General Instruments
CF596 processor and a Futaba 9-ST-12 display module.
Prinztronic SC4001M circuit board.
Qualitron 1450 scientific calculator
Qualitron Scientific Calculator, Model 1450, S/N 1001516
Functions: ASMD, scientific functions
Technology: MOS-LSI (Rockwell A6500CA)
Display: 8 digits, vacuum fluorescent module
Dimensions: 75W x 145D x 35H, weight 250g.
Manufactured: Qualitron, 1976
The Qualitron 1450 from 1976 appears to be a later and more capable version of the Prinztronic machine above. The 5 memory keys have been reduced to just Store and Recall, and replaced with base-10 logs, powers, and two levels of parentheses.
The
circuit board is similar to the two machines above, but with a
Rockwell A6500CA processor and a Futaba 9-ST-10 display module.
A ribbon cable has been added for the keyboard connection, but there
are still plenty of loose flying leads to the switches and power
connector.
Qualitron 1450 circuit board.
