80-Bus News


January–March 1982, Volume 1, Issue 1

Page 14 of 55


This is a program that runs on a Nascom 2 under CP/M, and pretends to be an improved version of Nas-Sys. The improvements consist of additional routines to move sections of the memory to disk, and read them back. The details of how to do this have appeared in the second issue of Micropower, a magazine that says quite kind things about this magazine. As quite a lot of typing is needed, I will repeat here the offer I made in the Micropower article. Anyone who wants a copy of MONITOR.COM should send a disk, initialised for their system, plus a pound for postage, packing and not a lot of profit! Frankly, if you have no desire to use all the programs you wrote before you had your disk drive/s, or have a hardware way of switching to Nas-Sys, you don’t need this, so there! As an aside, I should mention that the rather primitive disk read and write routines I have written for the program don’t work for files longer than 16K. There, saved you the effort of writing to tell me!

For those who have lost INMC80-3, my name and address is: Chris Blackmore, __ _____ ____, Ilminster, Somerset, ____ ___


I just converted my EPROM Naspen to use the somewhat altered screen addressing of my system, in a RAM version loaded from disk by MONITOR.COM, and am rather pleased with myself! I wanted Diskpen, but there was no more cash to hand, so that was that, for a while. See later in the episode for details of another editor.

Of course, the files produced by my rather clumsy modifications are not quite CP/M compatible, having only Carriage Returns where there should also be Line Feeds. I get round this slight problem by using another program, whose function is to grab the Naspen file left in memory by the converted Naspen, add line feeds to it and store it as a CP/M file on disk. They can then be edited again with CP/M compatible editors, if necessary, though I keep my working copy on tape, ready to send in for publication.

Meanwhile, here for your interest, if any, are the changes to Naspen needed if the VDU RAM in your system is at F800H:

AddressChange thisTo this
B86911 D0 0B11 D0 FB
B8A211 09 0811 09 F8
B9IC11 EA 0B11 EA FB
B94D21 8A 0B21 8A FB
B95311 4A 0B11 4A FB
BB9821 80 0A21 80 FA
BBD321 8A 0B21 8A FB
BBE111 8A 0B11 8A FB
BBF521 8B 0B21 8B FB
BC0221 90 0B21 90 FB
BEB611 E3 0B11 E3 FB

One slightly unexpected problem I had during the conversion of Naspen was that the board I was reading it from, a Merseyside Nascom Users Group EPROM board, doesn’t seem to send out a RAMDIS signal. Filling the RAM addresses concerned with FF’s enabled me to copy the program to an area that wasn’t duplicated by more than one board. You may well ask how much RAM there is on the new system... I hardly like to go on about this, but it is a certain manufacturer’s 64K page mode job, and what was memory plague, anyway? I should know better than to write that, as I am proposing to reassemble the venerable Marvin soon, so that I can play at Nascom 1/2 system games.

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