Disks

Disk Systems

It had to happen, three competing disk systems for Nascoms. Two from the States, one via our old friends at Barnett, one via Airamco in Scotland, and the third is a British designed one available from a consortium of Nascom dealers, and originating from the nether depths of Farnborough, Harrow and Kingston. Now, at this stage, we know very little about the Comp system, nothing about the Airamco, and an awful lot about the Henelec/​Gemini system. In fact the non appearance of the October – November issue of the INMC80 News is directly attributable to the Gemini Disk System. You see, the two main editor/​typists involved with the INMC have been up to their eyeballs getting the thing ready for production. No excuses, but the laws of nature still only allow for 24 hours in a day (I’m afraid we’re still working on that one, very tricky !!).

We don’t intend to review the systems here, as that would be a trifle biassed, but by Christmas there will be some 200 Gemini systems around (and who knows how many of the others), some points about disk systems ought to get a look in. We haven’t heard from a single member owning either Comp or Airameo systems, and at the time of writing Gemini systems are only just going on stream, so we haven’t had any user feedback on that either. But as we know a lot about the Gemini, and the majority seem to be going to INMC80 members, a few hints and tips won’t go amiss.

Now the EBASIC supplied with the system works on ASCII disk files, so how do you get some of your nicer Nascom Basic programs onto disk without the tedium of typing them all out again. Easy. First LIST the Basic program to tape. How? Load the program under Nascom Basic, go into the Monitor, type X0, and warm start Basic. Zap a cassette into the recorder, start it up, set the Basic WIDTH to 80, set the LINES to 32000, and then LIST. Your Basic program goes to tape as an ASCII file. If there are a number of programs to be transferred, copy them to tape at the same time, as changing from NAS-SYS to CP/M gets a bit tedious if repeated too often. Ok, so now we have a tape of the Basic program(s) saved as ASCII strings, how to get it onto disk.

Because the inimitable RB had more than a passing influence on the design of the software for the Gemini system, there is a routine hidden in it which scans both the keyboard and the serial input. Does that ring any bells? If not, you haven’t understood how NAS-SYS and Nasbug work. Anyway, Under CP/M, PIP.COM is really quite clever. It’s not just a disk copying program !!! In effect, it can copy anything from anywhere, and put it someplace else. We want the tape (which because of the scanning of the serial input), comes from the keyboard routine to end up as a disk file. In CP/M, the keyboard and video are refered to collectively as CONSOL so we want to PIP from CONSOL to disk. Snag, the stuff is coming in as a continual bit stream, so there will be no time for the disk system to stop and shovel that data away whilst the data is coming in. So effectively we must load it all into a buffer first. PIP has just such a command.

A>PIP FILENAME.BAS=CON:[B]

The [B] is a PIP option to buffer the input in RAM before sending it to disk. Give the disk system that command, wait until a prompt appears and start the tape. The ASCII strings on tape will be gobbled up into RAM, and when the data is finished, type ‘ctrl/S’ to tell it to write it to disk and “ctrl/Z’ to tell it it’s finished. If you only have 16K of RAM and the program is a long one, you won’t be able to load it all at once. Load about 8Ks worth, stop the tape, type ‘ctrl/S’ to write the first bit to disk, rewind the tape a bit, and having written the first half away, restart the cassette. The file will be a little screwed up in the middle, but having got it on to disk you will have to edit it a bit using ED anyway, so it shouldn’t be too difficult to unscramble the overlap in the middle. Don’t expect to be able to run a Nascom Basic program under EBASIC, they’re syntactically different, and EBASIC is particularly fussy about spaces between reserved words. Unless it is the simplest program