INMC 80 News


October–December 1981 · Issue 5

Page 66 of 71



by R. O’Farrell


Due to a prolonged stay in hospital, Christmas, and the pressures of business, progress on the Pascal front has not been as quick as desired.

It is hoped to obtain a major subset of Pascal in the near future, which will be compiled for the Nascom under Nas-Sys. Watch this space for details. There is also available from the program library an implementation of the Chung and Yuen Tiny Pascal, which uses a Basic program to compile to P-code, and then runs the P-codes in a machine language interpreter. The whole can fit in a 32K machine! (using ROM BASIC). Xtal Basic will require more memory, or alternately to write the P-codes to tape and reload with the interpreter. Remember that P-codes are not position sensitive within the memory map of the machine. They cannot, of course, be moved around relative to each other within a block, but can be put anywhere in the memory map as a block, provided the Interpreter knows about it. Rewriting the Tiny Pascal in terms of itself, so that the first level bootstrap has been made, is under consideration, but such a project is marking time pending the arrival of the major Pascal subset.

It is hoped shortly to have a language called BASEX (BYTE Books) implemented for the Nascom, and there has been a suggestion that there may be a Tiny C available. This latter is dependent on permission from the authors, which is being sought.

The UNIX operating system for the PDP11 is written in the C language. The book Software Tools (reviewed elsewhere in this issue) is written on machines running under this system, and admits its debt to that system. Reading that book and what else has been written about the UNIX operating system would lead one to believe that it is a most interesting system. There have been some look-alikes published for microcomputers. In particular, one called OMNIX, which has been temporarily withdrawn for delousing, and CROMIX for Cromemco machines.

Interesting Points.

If one has a Nascom IMP, and suffers an occasional stutter or repetition of the character being transmitted when the handshake occurs, or other garbage being printed at about that time, then the cure may well be to pull the handshake line to +5V with a 200-300 ohm resistor, which may be connected from pin 8 of SKT 1 on an N1, or from TP3 on an N2 to a suitable connection point. According to our beloved chairman, D.R.Hunt (please can I stop banging my head on the ground and grovelling on my knees? It’s very difficult to type accurately like this.), according to our b.c., D.R.H., the hand shake line inside the Imp is pulled up with a 1k resistor, which he says is wrong, Wrong, WRONG for an o.c. output. He says that it should be maybe as low as 150 ohm (grovel, grovel – he’ll say I’m wrong – grovel, grovel). Anyway, the mod. most certainly does work, and cuts out all duplicated and otherwise erroneous characters. Thanks, David (grovel, grovel).

Those using the Nascom 1 power supply, which has three three-legged device heatsinks in a row (current say two to three years ago) may experience intermittent system shut downs, bars on the T.V. screen, and other undesirable happenings. Try putting a heatsink on the little square bridge rectifier. If

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