HPR4506: The UCSD P-System Operating System

Hacker Public Radio

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