Demonstrating PROLOG on APPLE II

ABSTRACT

The purpose of this demonstration is to prove that the implementation on a micro computer of a complete version of an A.I. language, PROLOG in our case , is a to day reality.

We present the Apple II version of a complete, portable, Prolog system [1]. The system is imple­ mented in Candide. a language specially designed to write the Prolog interpreter. This language pro­ duces code for a virtual machine Micromegas. It i s important to notice that such a system could not be implemented on a micro computer without using a floppy-disk virtual memory. We have demonstra­ ted in a previous paper that this approach yields reasonable performance with good reliability.

CARACTERISTICS OF THE IMPLEMENTATION

The system is im~lemented on an APPLE II,

with

- 'liiK uf memory

- t.wo 1'10 Kll flOJ1PY disk~;

• ilrHf tho 1,1neuaeo card ( + 16 Kb, and UCSD Pasca 1 l for u price of about ~2500.

The Micromegas emulator has been embedded into the UCSD Pascal system and consists in 10 pages of Pascal code (initialisations and I/0) plus 15 pages of 6502 machine language code (per­ forming the instructions of the Micromegas machine). The Prolog interpreter occupies 12Kb of Microme­ gas code. The virtual memory system is implemented on the two floppy disks and the main memory paging area occupies 40 pages (of 256 bytes).

A complete version of the system was opera­ tional on May 81. Despite of some slown&ss it re­ mains very usable, thanks to its improved interac­ tivity. First experiments with the system show that having Prolog available on a micro computer is very stimulating. A lot of programs have been written with this new version. In particular, already exis ting Prolog programs have been trans ­ lated such as a natural language communication systlm. ·

This version allows to develop Prolog pro­ gram in nice conditions (with two floppies. you cdn have up to 50 pages Prolog programs). It is alsn very suitable for teaching.

DEMONSTRATING PROLOG ON APPLE II

A. Colmeraue r , H. Kanoui, M. Van Caneghem

Groupe d'Intelligence Artificielle Faculte des Sciences de Luminy Universite d'Aix-Marseille II 13288 Marseille Cedex 9, France

THE DEMONSTRATION

The capabilities of the system are illustra­ ted by a collection of small Prolog programs deve­ loped in our laboratory, particularly a Natura l Language data base query system. We will try to run every Prolog program suggested by the participants, at the conference.

During the demonstration, we will be pleased to discuss the transportation of the system to other machines (large or micro) with interested poeple.

A fully documented version of the Apple II Prolog system will be delivered next September. A Micromegas implementation manual will be also available and, on January 1982, a Fortran or Pascal Micromegas'emulator will allow to run the system on (almost) all computers.

1. Last steps towards on ultimate Prolog (in the same proceedings).