UCSD Pascal

Created during the latter half of the 1970's, UCSD Pascal is an interpreted version of the Pascal programming language developed at the University of California, San Diego under the leadership of Kenneth Bowles and gets its name from the initials of the university.

The system could be run either as operating system that runs the microcomputer, as a layer that takes over the user interface of the computer but relies on a host OS for all I/O running of hardware, or as an ordinary task (i.e. any other program). The system uses a p-machine virtual machine runtime derived from the original ETH Pascal implementation.

History

The UCSD Pascal System is based on the ETH Pascal System and uses the same p-code interpreter/virtual machine. It was initially a straight port of the P2 Pascal system to the types of microcomputer systems that were prevalent at the time in the USA. Up until that time most Pascal implementations were on mainframe and minicomputers and it was believed that the system was too large to be used on micros. The French Micral microcomputer however was sold with a Pascal system port a few years earlier despite being based on a lowly 8008 microprocessor. That inspired educational users of the language, since it opened up the possibility to give individual students access to a fairly cheap personal computer to develop their software on.

The self booting version of UCSD Pascal was alongside PC DOS and CP/M, one of the three operating systems that were offered for sale for the IBM PC when it was introduced in 1981. That appears to have been more symbolic than anything else, as early as 1982 PC customers that had ordered UCSD Pascal when the PC was introduced, complained that they never got the system shipped to them. So that it appears the system existed in IBM catalogues but there was never any intention to ship them in any volume.

UCSD Pascal is often put forward as the first Pascal implementation for microcomputers, but in actuality Micral Pascal predates it by a considerable amount of time.

Implementations

OS/2 tools based on UCSD Pascal

• Cabot UCSD Pascal - Commercial
• Pecan UCSD Pascal - 16 bit only
• ucsd-psystem-xc - Open Source

OS/2 tools that offer some UCSD Pascal compatibility

• Free Pascal - Open source - Very limited compatibility in more recent versions.
• Extended Pascal - Commercial

While EP is more advanced than UCSD, some extensions present in the system originated in the UCSD system so porting to EP is not too difficult.

• Microsoft Pascal - Originally based on UCSD but the two diverged fairly soon, porting UCSD to MP is really easy though.

Operating systems based on, or compatible with UCSD Pascal

• Advanced Operating System (AOS)
• Apple Pascal - Commercial
• BOS - Commercial
• Cabot UCSD Pascal - Commercial
• Pascal MicroEngine - Special version of UCSD Pascal III
• Pecan UCSD Pascal - Commercial
• SofTech UCSD Pascal - Commercial

Publications

• K. Bowles: Beginners Guide for the USCD Pascal System - McGraw-Hill 1980, ISBN 0-07-006745-7
• Randy Clark; Stephen Koehler: The UCSD Pascal Handbook: A Reference and Guidebook for Programmers - 1982, ISBN 0-13-935511-1

Links

• The UCSD Pascal System
• The UCSD P-System Museum