80-Bus News

The extension file is a chance to add some extra facilities to NASPEN. I have included a printer driver for a centronics driven RX80. The main reason for this was that I found I had three program modules fighting over the print format if I used the built-in Polydos routines. It also gave the opportunity to invent a way of putting control sequences to printer. The main problem is that Naspen will not store an “escape” character, because this code is used to terminate a Naspen command. I have used a “Control D” which can be stored in with the text, to replace the “escape”. This means that most if not all of the print-modes of the EPSON RX80 can be switched on and off, at will, by embedded “escape” strings. A further addition of the extension file is that the system can be restarted by a NAS-SYS “EB000” command which warm-starts NASPEN. The overlay file will have been lost, because the “Exec” overlay will have been loaded by the return to Polydos but it is not required once the main Naspen programs have been loaded and cold-started the first time. The warm start proved most necessary with the disk system, because it is easy to call a wrong file-name, or one that already exists. Either of these errors will blast you back into Polydos command level. (Rather like a touch of the snakes and ladders.) Obviously a rather more sophisicated file handling routine would allow for default file extensions and would automatically overwrite an existing file, renaming the existing version as a “.BK” backup version. The fun of getting that going is all yours!! An even more useful addition would be to toggle the screen with some unused memory and allow the operator to view the disk directories whilst in Naspen.

Some further minor changes were made to Naspen to indicate differences from the original prom version, the title was changed to read “NASPEN PDOS4”. The initialisation routine was changed to give 32000 bytes free instead of the original 11000. Although this is supposed to slow down the operation of some commands, I have not found it as big a disadvantage as the space restriction.

There are a few points to take note of before committing your epic novel, or autobiography to “Polypen”. DON’T use the “NP” extension for any other files. I use the extension “nt” for my Naspen text files. Remember to patch the printer reflection on your files before you submit them to “Polypen”. The disk save routines save all memory from 1000H.

To avoid compromising copyright on the PolyDos listing I have not included the comments. If you have bought PolyDos you will have a manual which explains all. I was amazed by the ease with which I managed to effect these changes, and it speaks volumes for the quality of the manual that the first successful assembly of the file-writing routine worked first time. (For a comparison note how many non-Digital Research textbooks are recommended for CP/M tinkerers ).

Next issue

Subject to probable change the following items should appear in the next issue of 80-BUS News, a special ‘back-from-holiday’ issue !