80-Bus News


January-March 1982, Volume 1, Issue 1

Page 31 of 55


Last summer I made a trip to my local friendly Nascom dealer to buy a copy of the source of SYS. Rather than PIP each file across by itself, the guy copied the entire disk, and then erased the files that I shouldn’t have. These files included DISKPEN. :

CP/M doesn’t erase the whole file when a file is deleted, all it does is change the first byte of the file’s directory entry from 00H to E5H, so when I got home, I just changed the byte on the erased files back to OOH using D-DOS. All I then had to do was find a way to stop the E and W commands from disappearing as soon I used “Insert”, because, of course the program hadn’t been initialized, and so didn’t work properly. It was an easy job, all I had to do was alter a couple of RETurn’s to CALL’s. Have a look at your disk with the source of SYS on it, if you haven’t recorded anything else onto it, you might be lucky too! (Oh know you won’t, they’re wise to that one, and the SYS source and DISKPEN are now on separate disks, anyway. Watch out, they’1l be round to collect the royalties! – Ed.)

A couple of criticisms of DISKPEN. It needs a ‘continuous change’ command, which is to ‘c” as “I’ is to ‘i’. The ‘change keyboard case’, U, needs to be duplicated by ‘u’. (Why, you lost the use of your shift key or something, or is it because it was ripped off and you haven’t got the documentation? – Ed.) It would be nice if the ‘find’ commands supported ‘wild’ characters, as CP/M’s CCP does, using ?? and *.

Incidently, just to save the editor’s blushes, I must admit that I don’t use DISKPEN. I use Michael Shrayer’s Electric Pencil II as a text editor, I find it far preferable to DISKPEN except for it’s lack of on-screen formatting, (It will only format what’s being sent to the printer), but then, it is three times the price of DISKPEN, and only works with a 64 x 16 character screen.


Wouldn’t it be nice if we could use the top line of the video display as if it were any other line. Some of that information that gets missed because it scrolls off the screen before we manage to hit 7S could be read, if we could see sixteen lines of text instead of just fifteen. (See earlier ‘Ed.’ – Ed.)

Having the screen handling part of the CBIOS in RAM makes it so easy to adapt. Instructions follow: First go to your local friendly dealer and purchase the source of SYS, well worth the tenner that it’1ll cost you, and using Electric Pencil, or whatever your favourite text editor is add the following code.



VL16 EQU VRAM+03CAH Amongst the video switches add

SCROLL16 EQU TRUE 316 lines scrolled Just after the beginning of the video routines, you’1ll find

;Copy down screen.

LD BC, VEND-VRAM-16-10-6 From this, remove the *-16’ A bit further on you’ll find:


CRT40: LD DE,VLI Between CRT40: and LD DE,VL1, add the following:




This is an OCR’d version of the scanned page and likely contains recognition errors.

Page 31 of 55