Nascom News­let­ter

cheap.

Incidently, if you read the May 1981 copy of Personal Computer World there is a very good description of implementing a Mini-DCR on a Nascom, which led, I believe, to the C.I.E.L. system. One of the reasons why this system is so dear is the use of an S.I.O. and an 8″x8″ P.C.B. with 2k RAM.

On initialisation a pointer to the system’s command table is written to 0C80H, 0C81H (a slightly inconvenient address, I’ve moved mine to immediately below the tape system buffer), which means that you can set up your own command table and expand the “HOBBIT” monitor to a full system monitor. The manual explains how to set up your own command table, and this feature, together with the information on the addresses and routines within “HOBBIT” make the system extremely flexible and easy to expand. Of course it would be a lot easier if that source code was available…

As mentioned earlier I have found the system very reliable. However, the price of the mini-cassettes is a bit off-putting at about £3 each for the Philips certified tapes, so I’ve tried lots of different makes of dictating tapes, all with complete success. The cheapest, so far, from Dixons is £1-23. One drawback is that they are longer than the Philips tapes. This does not increase the amount of storage but does increase the time it can take to Mount a tape as considered earlier. Another is that the tapes require a “write-enable” plug, and these are not supplied with dictation tapes.

So far I have said nothing about the file-handling facility in BASIC. The “HOBBIT” system itself does not support this, but IKON sell, for an extra £10, a “Microsoft BASIC Upgrade Kit”, which is a cassette (for the Mini-DCR)​(not forgetting the cassette itself is worth £3) containing 4 different versions of a routine to add full file handling routines. One routine each for Nas-Sys 1 with either tape or ROM BASIC, and repeated again for Nas-Sys 3. In this case the old monitors are not supported (is there anyone still using them?). Also, generously, the source code is included, (in ZEAP format), for it to be individually adapted.

The facilities provided are (from the command made of BASIC, or within a program):– Select a drive (ie. supporting a 2-drive system), Open a named file for writing to, Writing a string of Up to 80 characters to a file, Closing a file, Open a named file for reading and finally Getting a line of text from a file. Error trapping includes an “X” legend to denote a different error from the ones described above, which are also supported. The error code is followed by the program line number where the error occurs.

This program also works quite well, its only restrictions