HP 9830A

The Hewlett-Packard 9830A is a rather interesting desktop "calculator" from 1972 (it is actually a computer, but was marketed as a calculator to make it easier to buy for large companies that have been taken over by bureaucrats, as buying a computer at that time was seen as a big deal).

It has a 32-character red alphanumeric LED display, a full keyboard with 10 programmable function keys, and a digital cassette tape drive, which takes standard audio cassettes and holds about 35000 words of data (~70kB) per cassette. Audio cassettes that are specified at up to 60 minutes in length and have a white or transparent case are most reliable (these case colors make it easier for the tape drive to detect the transparent bits of tape that are at the ends of the tape). CrO₂ magnetic tape material works well.

Its processor architecture is based on the 16-bit HP 2100-series minicomputers, but implemented in a bit-serial way (the processor's ALU only processes 1 bit at a time instead of 16, which makes it slower, but requires fewer transistors to implement and is therefore cheaper). The processor's frequency is 8MHz and can execute about 75kIPS.

The machine runs a pretty featureful version of BASIC, which can be additionally expanded with plug-in ROM modules (to add e.g. matrix operations, plotter control, etc.).

The 9830A was usually paired with a 9866A thermal printer, which could only print characters (upper-case, 5x7 dot matrix, 80 characters per line), but at 240 lines per minute. You can use standard fax machine paper rolls in this printer.

The calculator itself weighs 20kg and the thermal printer 17kg. Not only is it built like a tank, it also weighs like one!

As for the power consumption, the calculator on its own uses about 90-105W when idling, the printer on its own 80-95W, and both together about 170-225W. The power factor is pretty decent — a steady 0.76.

My HP 9830A has 7904 words of memory (maximum possible, ~16kB), a 9866A thermal printer, a 9862A plotter, and a 9865A external cassette tape drive. It's still fully functional after more than 45 years!