HP 9800 SERIES DESKTOP COMPUTERS

The HP 9800 series was family of programmable calculators (later called desktop computers) which replaced the HP 9100 calculator. The HP 9810 was a keystroke programmable computer with magnetic cards, while the HP 9820 featured HPL, where instead of variables such as A1 and J2, it used numbered registers r1, r2, up to r199999 and so on.
This HPL program for the HP 9825 generates a list of prime numbers:
0: fxd 0
1: prt 1
2: prt 2
3: 1->P
4: for C=2 to 1000000
5: P+2->P
6: for N=3 to P/3
7: if int(P/N)
★ N = P; gto 4
8: next N
9: prt P
10: next C
The Hewlett-Packard 'HP 9830A' was the top of the line of the 9800 series programmable calculators, later called desktop computers, introduced in 1972, similar in capability in many ways to the later IBM PC which had BASIC in ROM.

The success of the HP9830 led to a next generation with faster logic, the HP 9815 keystroke programmable, HP 9825 HPL, HP 9831 (BASIC) and HP 9835 (BASIC) which used mini cartridges rather than cassette tapes.
The HP 9845 introduced first a monochrome, and then a color CRT to replace the small 1 line LED display which was becoming obsolete. These came out of the Fort Collins calculator, and later named Desktop Computer division. The HP 85 and HP 87 were smaller BASIC language computers out of Corvallis, Oregon with small CRT displays.

Contents

HP 9830 Description

Programming

Uses

Other BASIC computers

An ancestor of modern personal computers

Notes

External links

HP 9830 Description

They were built with a processor similar in architecture to the HP 1000/2100 series minicomputer with 16-bit memory address, and an AX and BX general register. They ran at a speed comparable to the first IBM PCs. They could draw a mesh of a ''3D SIN(X)/X'' function with no hidden lines over the course of several minutes, which a modern Pentium 4 can do in a blink of an eye.
Because programs were designed to run from ROM (read only memory) the call subroutine instruction had to be changed because in the HP211x the return location was written in the first location of the subroutine. Instead, another register was created to keep track of return locations on a separate stack area, like more modern processors. ^[1]
It 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.
A computer controlled cassette drive using audio cassettes with clear leaders was used for storage, with random access to file by number, but a hard drive could also be attached.
The matching line thermal printer was quite fast, printing one horizontal line of dots at once. The speed of a page was faster than later dot matrix printers, and not much worse than modern ink jet printers. HP would incorporate thermal printers across many plotting and terminal products later.

Programming

Compared with modern computers which typically require programmers to define calculations by means of complicated programming languages, these were designed for direct algebraic entry, so as to not distract the intended users (scientists and engineers) from the task at hand. BASIC was similar to FORTRAN used by engineers on the