80-Bus News

Pilot Feedback

Quite a while ago, I had a letter from R.B.Poate, who said, “I would suggest that you use Naspen or something similar for your line numberless editor.” This is in fact, very near to what I actually intended to do. My plan was to say something along the lines of “Right, here is the specification for each of the parts of the Pilot interpreter, now let’s each write a bit…” Nasty, isn’t it? The specification for the editor only has to state the way the program is stored, and where in memory it actually is, and the task of adding your (or somebody else’s) editor is left to you. Do I hear howls of “Cop out!"?” Probably, but you see I don’t want to write two or more versions of the same thing, and my one is to run under CP/M, not Nas-Sys. That is why all the monitor calls in the code so far printed go to vectors.

Without Further ADO…

The editor will be any code you care to write that enables you to manipulate the stored program to your own satisfaction. It fits into the free code from the earlier episode where lines 1490 to 1500 currently are. Yes, Heloise, I do know I forgot to resequence that bit. The program storage area starts at location RAM, and the first two bytes hold the address of the last byte of the program [low byte first, of course.] Having tried more than once to write a decent editor program, I am copping out yet again; I shall be using an editor written by the genius at Hi-Soft. See next section… In order that the programs we all produce will be compatible, we will all separate lines with the combination of characters, CR LF [in other words, 0D 0A]. This will cause howls of apathy, or possibly anger I shouldn’t wonder, from those of you without CP/M and disks, who would have preferred to use 0D on its own. Why aren’t you writing this?

The Load module, which replaces lines 1450 to 1460 of the listing, reads from tape, disk, Tibetan prayer wheel, or other mass storage unit into the memory, at location RAM. Users of any Nascom monitor, it is your turn to be smug, because the monitor will do this for you with very little extra code of your own.

The Save module, lines 1470 to 1480, it will hardly surprise you to learn, transfers the program to the storage medium from the memory. Now do you see why RAM and RAM+1 hold the address of the end of the program? [If you don’t, why are you reading hard core computer magazines?]

A Soft­ware Review.

This review concerns the “Z80 development package” currently being sold by Hisoft. The package consists of an editor, an assembler, a debugger [*** semantics error ***] and another program whose use I have not yet discovered. The package sells for 50.00, a price which compares extremely favourably with the amount you would need to lash out to buy Diskpen and Macro 80, [about 150.00, I think.] The assembler works very well, also fast. It can handle source files far larger than your computer’s memory, as can the editor. The editor is a joy to use (I know!! – Ed.), especially after you have become used to the horrors of ED.COM. An especially nice feature is the way it copes with very long lines, by scrolling the whole screen across, instead of wrapping round to the next line, or crashing, or any of the weird things some editors do when you ask more of them than their authors intended. The debugger takes a while to get used to, but is very useful, I have found it very good indeed at finding the silly errors in my early attempts at converting the skeletal Pilot to a CP/M form. If this package does not seriously dent sales of both Diskpen and the grossly overpriced Macro 80, I shall be very surprised indeed. So that you will not think I am being paid by Hi-Soft to say these nice things about their product, I will just mention in passing that I was very annoyed to have to wait over a fortnight for delivery. It was worth waiting for, but why was it necessary to wait?

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