The HP 9825 was introduced in 1976 as a replacement for the earlier 9800 series of calculators, particularly the Model 20 (9820) calculator. It had a full QWERTY keyboard and used a 32-digit LED alphanumeric display.

They were very popular as instrument controllers.

The hardware was also used as a base for the HP 9831A BASIC-language computer.

This is identified as a ET-8355, a "HP 9825 Monitor." Behind the front you see here is a power supply and six plug-in slots. There are also two DIP plug-ins and a larger multi-way connector.

From a couple of former HP engineers who used the Monitor:

This is essentially a front panel control for an HP 9825 processor. It gave the processor a minicomputer-like front-panel interface that allowed you to examine and change data in individual memory locations, single step and run programs, and basically watch and control the processor's operation by hand. It was used to troubleshoot processors and computers. It was needed because the HP 9825 booted directly into the HPL interpreter, so it wasn't designed to give you access to the bare-metal hardware from the 9825's keyboard and display.


This is a hand-coded state machine that was used to debug the BPC hybrid processor used in the development of the 9825, there is a 40 pin (20 pin double sided) connector that plugs onto the processor board that provides access to the multiplexed address/data bus and bus control (request/grant). It was possible to halt, step and run the processor as well as examine the contents of memory.

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The slots accept three cards: MNTR-66501 (display), MNTR-66502 (logic) and MNT-66503 (logic).

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The 9825 introduced a programming language called HPL ("High Performance Language"). It supported strings, arrays, looping and even interrupts.

Here is an example program to generate 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

I recently got an HP 9825A calculator from about 1982. I still have tape cartridges with some HPL programs that I would like to transfer to a PC. So, now I am searching an emulator to run HPL on a standard PC. Does there exist anything like that ?


Answer 1:
Back in the late 80's or early 90's, a company called Oswego Software marketed a series of translation utilities to convert from various proprietary and/or obsolete languages to more readily available platforms. They had, among other things, an HPL to HP Series 200/300 BASIC converter, described in their literature as a "four pass translator." They claimed it would translate about 90% of an HPL program. I figure they were implying that the remaining 10% had to be hand coded. It also included a utility to send HPL code from a 9825 to a Series 200/300 machine over the HP-IB interface. I would imagine that one could also use HT BASIC or HP BASIC for Windows on a PC to run the resulting Series 200/300 program (more or less) directly.

Alas, I do not have this utility, so I cannot tell you any more about it.


Answer 2:
A company in Salt Lake was once going to create a version of HPL that ran on a personal computer (before IBM introduced the PC). They advertised the product. As one of the later developers of the HPL language, I flew from Colorado to Salt Lake to investigate. Turns out the ad was a tickler to see if there was a demand for such a product. They never even started work on the project. To my knowledge, that was the only third party to ever even consider moving HPL to a different computer.

Steve Leibson

This advertisement appeared in the March 1976 issue of Scientific American.

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Updated June 14, 2016