The **Casio Memory B-1**, also known as the H-816, is a handheld calculator manufactured by Casio Computer Company Ltd. in Japan. Estimated to have been produced around 1978, this calculator features a sleek, two-piece plastic case in white and dark brown, with brushed aluminum panels adorning the front. Despite its age, the calculator has a quality feel, thanks to Casio’s signature miniature escutcheons on the bouncy keys.

Measuring approximately 77mm x 136mm x 19.7mm (W x H x D) and weighing 108g without batteries, the Memory B-1 is a compact and lightweight device. It runs on two AA batteries or an optional AD-2S adapter (center negative) and consumes a modest 0.2W of power.

The calculator boasts an 8-digit blue VFD display with no ninth digit, providing clear visibility through a slightly tilted neutral display filter. Its capabilities include four basic arithmetic functions, square root, percentages, delta percent, and a switched floating/2 decimal point mode. Additionally, it features a three-function memory and a manual constant function.

Under the hood, the Memory B-1 is powered by a NEC D1877C E87346 28-pin DIL CPU and a flat-faced glass VFD display unit (NEC FIP LD8225/FIP8A5 No. 8J). The main CPU board (ref F8X-1A) sits loosely on top of the keyboard assembly, connected by 16 sturdy copper wires.

Logic:

- The (C) key cancels an incorrect numerical entry, and (AC) clears the calculator
- Manual constant is available for all four functions by hitting the function key twice
- Input overflow is suppressed, and inputting a ninth digit is ignored
- Negative sign is shown in the immediate left-hand digit, limiting negative numbers to seven digits
- Divide by zero shows an unrecoverable “E” error
- Overflow is indicated by an “E” in the final (right-hand) digit and is not recoverable
- Memory store is not indicated, requiring the user to remember it
- The (AC) function clears the memory, potentially causing loss of stored values
- Negative square roots are allowed and result in negative numbers
- A switch on the front toggles between floating decimal point, “round down,” and fixed two decimal places
- The calculator suffers from the “divide to negative zero” bug, where dividing 1 by 0 repeatedly results in “-0” before eventually displaying 0

The Casio Memory B-1 is a well-constructed and compact calculator from the late 1970s, offering standard arithmetic functions, memory capabilities, and a convenient display. While its logic has some limitations and quirks, it remains a notable addition to Casio’s lineup of handheld calculators from that era.