HPR4506: The UCSD P-System Operating System

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01 Overview

This episode is about the UCSD p-System operating system.

UCSD p-System is an operating system from the late 1970s which carried on into the 1980s.

It ran on a variety of different micro and mini computers.

The notable thing about it is that it ran programs on a portable virtual machine rather than directly on the native hardware.

This podcast episode overview will give a very brief overview of the operating system, its features, and its history.

This episode is for people who are interested in some of the more obscure history of the early microcomputer era. Don't expect to find something here that you can put to use in a practical way.

02 Pascal and UCSD

03 Commercialization

04 UCSD p-System Versions

05 Hosted Versions

06 Basic Concepts

07 File System

08 Virtual Memory and Multitasking

09 Architecture Independence with P-Code

10 Programming languages

11 The Fading Away of the p-System and its Demise

12 A Quick Tour of the p-System - Running it on Modern Hardware

13 A Quick Tour of the p-System - the User Interface

14 A Quick Tour of the p-System - OS Level Menu

15 A Quick Tour of the p-System - ASE Editor

16 A Quick Tour of the p-System - Filer

17 A Quick Tour of the p-System - Xecute

18 A Quick Tour of the p-System - DOS Filer

19 Conclusion

The UCSD p-System is an example of an operating system from the early days of microcomputers that did not follow the conventions that we are used to today.

It had features that were in many ways ahead of its time.

Here are some examples of this.

It was almost entirely written in a high level language, Pascal.

Programs compiled to p-code (or Pascal code) that ran on an architecture indepedent virtual machine.

Performance critical parts of the p-code could be compiled to native code.

The user interface did not use a command line, indeed there was none. Instead it used a menu driven user interface.

On the other hand it remained stuck on 8 bit limitations in a 16 bit world.

It was closed source proprietary product, and when the vendor lost interest, the product died.

It's an interesting bit of history, but I can't really recommend that anyone should expect to do anything useful with it today.

I still have a copy that I bought when it was a current product, but it has been many years since I even looked at it, and I only resusitated it for the sake of making an HPR episode.

20 Adendum - Performance Benchmarks

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