The 9830 and its successors were true computers in the modern sense of the term, complete with a powerful BASIC language interpreter.

The HP9825 was selected because it was portable – the only alternatives were phone access to time sharing computers which was not reliable from these locations.

They could draw a mesh of a 3D SIN(X)/X function with no hidden lines over the course of several minutes, a technological breakthrough for the time.

Instead, another register was created to keep track of return locations on a separate stack area, like more modern processors.

Some models (e.g. 9835B) used a 32-character 1 line uppercase LED display, which on the one hand might seem limiting, but on the other hand had the same effect as one-line window into a full screen editor which did not become common until the 1980s, with controls to go up or down a line, and cursor left and right, inserting or deleting characters.

They powered on ready to do math in "immediate mode", where you would type in an expression such as PRINT 2 + 3, and you would get an answer when you hit enter, without the complication of logging in, or the overhead of maintaining a big computer room and operator.

Arrow cursor keys were provided which could scroll up and down lines, and interactively insert or delete characters which was unheard of with most CRT or printing terminals until the advent of the screen editor in the late 1970s, and the programmer could single-step or check values of variables.

It was programmable in BASIC, which could be extended with ROMs to do graphics plotting, matrix math and string variables.

HP also produced a series of handheld pocket computers with a one-line display such as the HP-75, although such devices were not popular for long.

In 1979 the 85, the first machine in the HP Series 80 line of personal desktop scientific computers, was produced.

That division evolved to produce UNIX HP 9000 series workstations, also acquiring the Apollo Computer Company.