The **Casio Biolator H-801** is a vintage handheld calculator from 1975. It measures approximately 74mm x 125mm x 23mm and weighs 104g without batteries. Power comes from two AA batteries, though it can also run off an AC adapter plugged into a socket on the top left side. Battery life is estimated at 13 hours with manganese batteries or 34 hours with alkaline.

The Biolator has a sleek, rounded plastic case in three sections – black on the back, off-white in the middle, and black on the front. The top holds a colorful metallic panel, the middle has a neutral display filter, and the bottom has a brushed aluminum keyboard surround. The keys are typical squishy Casio style. An on/off switch sits on the left edge.

It uses an 8-digit vacuum fluorescent display in blue. There is no ninth digit. Features are basic – the four standard math functions but no percentages or memory. The Biolator functions provide some additional utility.

Logic notes:

- The C key clears the last entry, AC clears the whole calculator
- Extra digits beyond 8 are ignored
- Auto constant on all four math functions
- Seven digit negative numbers due to lack of ninth digit
- Overflow shows E in the first digit, not recoverable
- Divide by zero gives E, not recoverable
- Suffers from negative zero and divide to negative zero bugs
- Biolator functions only work 1900-1999, not Y2K compliant
- Day calculation shows day of week for a date
- Can calculate number of days between dates
- Biorhythm shows peak/caution/ebb days for physical, emotional, intellectual cycles

The Biolator H-801 is a fairly basic 1970s calculator with some novelty functions like biorhythms. Its sleek styling and rounded case make it pleasing to handle, but capacity is limited to eight digits. The biorhythm features are fun yet limited due to the lack of Y2K compliance. An interesting piece of vintage calculator history.