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Singer/Friden 1203 Desktop Calculator

Updated 1/12/2020

The Singer/Friden 1203 shows that in the years between 1970 and early 1974 (when this particular machine was made), Singer had quite an impact on changing the "feel" of traditional Friden calculator design practices. The 1203 is a somewhat strange exercise in styling -- very angular, space-age looking compared to its earlier predecessors which had strong signs of the much more conservative Friden style. The 1203 also has much more plastic in its construction versus the use of metal internal structures, keyboard bezels, and keyboard assemblies of the earlier Friden and Singer/Friden calculators. The 1203 had a stable-mate machine, the 1202, which was electronically identical, but did not have keyboard keys for the second memory register, or the switch enabling automatic accumulation of the first factors in multiplication and division calculations. The 1202/1203, along with the earlier and less capable 1201, were made in the USA, as opposed to the previous-generation 111x-series calculators, which were made in Japan by Hitachi for Singer/Friden.

Inside the Singer/Friden 1203

The 1203 uses a single Rockwell-made Large-Scale Integration IC (A4540) to provide the calculating intelligence of the machine.

The 1203's Panaplex Display in Operation

The 1203 is a pretty standard office-style four-function desk calculator, with 14-digit capacity. The display is a Burroughs Panaplex II display, with 16 elements. The display is driven by a combination of discrete transistor drivers for the segment lines (9 lines, 7 for the seven segments of each digit, one for decimal point, and one for the comma indicator), and three Sprague UHP 491 high voltage driver ICs for digit drivers. The left-most display element, while it contains a fully-formed digit, is never used. The right-most element, again a fully-formed digit, is used to indicate a number of status conditions. The upper horizontal bar of the 7-segment digit in this status location indicates that memory register one contains a non-zero number. The middle horizontal bar indicates if the number in the display is negative, and the bottom horizontal bar indicates that memory register two has non-zero content. In the event of an overflow condition, this digit position lights up as "E". When the "E" indication is given, a single press of the [CLEAR] key clears the overflow condition, but leaves the display intact, allowing further calculation. Pressing the [CLEAR] key twice clears the whole machine (except for the memory registers). The display also shows commas at every third digit in front of the decimal point to make reading large numbers easier.

The Singer/Friden 1203 has two memory registers, with [M+] and [M-] keys to add or subtract the content of the display to/from the memory register. There are two keys for each memory register related to recalling the content of the memory register to the display. The [MS] key recalls the memory register to the display, leaving the memory register intact, while the [MT] key recalls the register to the display and clears the memory register. A three-position switch on the keyboard panel controls summing modes for the memory registers. In the "OFF" position, no memory summing occurs. When set to the "Σ 1" position, the result of any multiply or divide operation is automatically added into memory register 1 when the result is calculated (by pressing another function key ([X], [÷], or [%]), or by pressing [=]). When the switch is set to the "Σ 1,2" position, the first operand of a multiply or divide operation (multiplicand or dividend) is added to memory register 2 as soon as the multiply or divide key is pressed, then the resultant answer is added into memory register 1 when the result is calculated.

The 1203 also has a [%] key, used in conjunction with the multiply or divide keys to calculate percentages. An example would be doing a mark-up calculation; let's say an item at a store currently costs $1.89, and the store manager has been informed that the item has had an 8% price increase. The manager wants to know what the new price should be. On the 1203, it's a simple matter: 1.89 X 8 % (which displays .1512, which is 8% of 1.89), then press the [+] key to perform the mark-up, resulting in 2.0412, or $2.04 for the final price. The same operation, but with pressing the [-] key, performs a mark down operation. The machine also has a [Change Sign] key which toggles the sign of the number in the display, and an [R] key which swaps the arguments of multiply or divide operations. The calculator provides automatic constant for all four functions.

The 1203 has a rotary switch on the keyboard panel which selects the method of decimal point handling the machine uses. Fixed-point operation can be set at any position from zero to seven digits behind the decimal point. An "F" position selects full-floating point operation, and a "+" position selects a dollars and cents mode with 2 digits behind the decimal point. An "N" position works the same as floating decimal mode, but activates the special Item Count register which is incremented each time the [+] or [-] key is pressed, accumulating a count of the numbers added or subtracted; useful for averaging and other calculations. When the switch is in the "N" position, pressing either of the [MT] or [MS] keys recalls the item count register to the display. The keyboard is of surprisingly high quality, using magnet-activated micro-switches for long life and reliability.

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

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