The Elka 103 calculator, manufactured in 1973 by ISOT in Bulgaria, features a bold design and stark coloring. It’s a product of the 1970s calculator price wars, utilizing cheaper labor zones to keep costs down. It’s a well-built calculator with a few quirks that make it an interesting piece of technology from that era.
The Elka 103 is compact, measuring approximately 70mm x 137mm x 30mm (width, height, depth), and lightweight at 120 grams, excluding batteries. It is powered by 6.0V DC, using four AA batteries, and also has an adapter socket on the top side for a 4.5-6V center positive adapter. The calculator features a solid red-backed case with a smooth rear and a matte black front. The top back of the calculator is raised by about 30 degrees, and the red display filter is raised even higher, featuring a “fine-line” design. However, this design lets in a lot of ambient light, which can reduce the contrast of the display. The brand and model number are printed in white on the lower front edge. The keys are described as squishy with medium travel but function effectively.
The display is an 8-digit red LED with a bubble lens, and there is a ninth digit for negative and memory indicators. The Elka 103 offers basic features, including four functions with percentages, square root, and a four-function memory.
The calculator’s components include a Rockwell A5502PB 7548 CPU, a nine red LED display with a bubble lens, six transistors, four diodes, 17 resistors, five capacitors, and a transformer TP024. The small CPU board, labeled E101M, sits loose above the main board/keyboard and is connected by a 23-way ribbon cable. The boards are secured using the case fixing screws. Disassembly is straightforward: remove the four screws on the back, two of which are hidden underneath the sticky “model number” label, and the case easily separates, hinging the back to the right.
Logic:
- (C) cancels an incorrect numerical entry; pressing (C) a second time clears the calculator.
- Input overflow is suppressed; keying in a ninth digit is ignored.
- It has automatic constant on all four functions.
- Overflow shows the result with all decimal points alight and is recoverable using (C).
- Divide by zero shows “0.0.0.0.0.0.0.0.” and is recoverable using (C).
- Negative numbers are shown with a “-“ in the far left (ninth) digit, allowing full eight-digit negative numbers.
- Square roots of negative numbers are allowed and result in a negative number.
- Memory storage is flagged by the decimal point of the far left (ninth) digit.
- Using the memory is a two-keystroke sequence: to add to the memory key in (M)(+), to recall (M)(=), etc.
- It suffers the pseudo fixed decimal bug: key in (1)(+)(.)(0)(0)(0)(=) to give “1.000,” which remains a fixed three-digit decimal number until more digits are required or you use multiply or divide.
The Elka 103 calculator is a robust device with a few notable quirks in its logic. It is a good example of the calculators produced during the price wars of the 1970s, utilizing cheaper labor zones to remain competitive. The calculator comes with a soft case and has a solid build, making it a reliable tool for basic calculations.
