The Casio Memory-8R, also known as the Y-811, was a handheld calculator produced by Casio Computer Company Ltd. in 1975. This horizontal format calculator had a two-piece case made of dark brown and light beige smooth plastic, with a slightly wedge-shaped design. The raised display area was tilted, featuring a neutral display filter that provided a clean, bright image of the numbers, along with two raised white ridges.
Measuring approximately 148mm x 72mm x 23.8mm (w,h,d) and weighing 114g excluding batteries, the Memory-8R was powered by 3V DC from two AA batteries. It also had the option of using an AD-2S adapter (0.2W) through a socket on the top left side. The quoted battery life was 9.5 hours for manganese dry batteries and 21 hours for alkaline batteries.
The calculator featured an 8-digit blue VFD display without a ninth digit for additional display. It was a basic four-function calculator with percentages and a one-function memory. The keyboard had a brushed aluminum surround with typical Casio key frames and medium travel, squishy-feel keys.
Under the Logic heading, the information provided can be summarized in the following list format:
- The (C) button cleared the last entry of a number, while the (AC) button cleared the entire calculator.
- Overflow on number input was suppressed, ignoring the ninth digit when typing a nine-digit number.
- An overflow error was flagged with the “E.” displayed in the first (right most) digit and was not recoverable.
- Divide by zero resulted in “E.” being displayed in the first (right most) digit and was also not recoverable.
- Selectable constant was available for multiplication and division only by double-pressing the function; e.g., (5)(X)(X)(4)(=) gave “20”, and (=) gave “100”.
- Negative numbers were shown with a “-” in the immediate left digit, but were limited to seven digits due to the lack of a ninth digit.
- The memory was an automatic accumulation memory, adding the result to memory every time (=) was pressed. (MR) recalled the memory, and (AC) cleared it.
- The calculator suffered from the negative zero bug, where (1)(-)(2)(=) gave “-1”, and then (+)(1) gave “-0”.
The Casio Memory-8R was a solidly built, early horizontal calculator with a basic four-function and percentage capability, along with a one-function memory. While it had sound logic, it lacked overflow recovery and had the negative zero bug, which were common limitations of calculators from that era.
