The Commodore SR9190R calculator, introduced in 1978, is a nice scientific calculator designed for durability and functionality. Manufactured by Commodore in Hong Kong, this calculator was built to cater to the needs of users requiring advanced mathematical capabilities.
The SR9190R features a sleek, two-piece stippled black plastic case with silver printed trim, giving it a professional yet understated appearance. The brand name is raised and printed in silver, adding a touch of elegance. The keys are a mix of light and dark grey, white, and black, with a black keyboard surround. Additional functions are highlighted by raised text, painted silver, making them easily identifiable. The keys are of the short travel, squishy type but are responsive and efficient. The display is heavily inset and tilted, featuring a red filter that enhances visibility, resulting in a large, bright display.
Powered by an internal rechargeable battery, the SR9190R accepts adapters DC-505, 707, 708, or 709, with the charging port located on the top side in the middle. The calculator also includes a power-save function that turns off the display to conserve energy.
The display is a 10+2 digit red LED with a bubble lens, including a 13th digit for negative, error indications, and an intervening digit for negative exponents, which are the same size as the mantissa digits. This setup ensures clear and precise readings.
In terms of features, the SR9190R offers a wide range of functionalities, including four basic functions, percentages, change sign, brackets, reciprocal, pi, register exchange, square root, squares, nth root, logs, trigonometric functions, statistics, polar coordinates, degree, radian, gradians, probability distributions, sexagesimal mode, integration, imaginary numbers, conversions, and a four-function multiple store memory.
The calculator’s dimensions are approximately 80mm x 147mm x 20-40mm (width, height, depth), and it weighs 152g excluding batteries, making it compact and portable.
The SR9190R is equipped with the following components:
- 1 x CPU: MOS MPS7201 3778 (week code 37 of 1978) 40 pin DIL, 0.6″ width black plastic.
- 2 x MOS MPS7001 039 2778 (and 040 2878) 16 pin DIL 0.3″ width black plastic.
- 2 x Mitsubishi MS4517P 7X77 16 pin DIL 0.3″ width black plastic (display drivers).
- 1 x 14 digit LED display module with bubble lens.
- 1 x diode.
- 2 x capacitors.
- 3 x resistors.
- 1 x voltage regulator Aztec AA4082.
The circuit boards include the keyboard assembly (GICO Japan GK412-1 K-1) (GICO 53.9.21 O-6), which sits clipped to the front by four plastic lugs. The main board (Commodore logo 201468 REV A) lays upright on top of it, separated by a piece of card. These are joined by a 22-way ribbon cable, with an equally long 22-way ribbon cable traveling underneath the batteries to the display module.
Disassembly is straightforward: remove the two long screws from the rear, and the back section lifts off easily, hinging from the bottom.
Logic:
- (C/CE) is used to cancel the last number entered and a second time to clear the whole calculator.
- Input overflow is suppressed, inputting a ninth digit is ignored.
- Negative numbers are shown with a “-” in the far left (ninth) digit thereby allowing full eight-digit negative numbers.
- The (F) or function key is used to select the operation in the upper label.
- The (XCHn) key is used to exchange the chosen memory register whilst the (X<>Y) key is used to exchange the calculator’s registers.
The Commodore SR9190R is a reliable scientific calculator with a comprehensive set of features. Its design, functionality, and durability made it a practical tool for various mathematical applications.
