80-Bus News

  

September–October 1984, Volume 3, Issue 5











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Letters to the Editor

Pertec Mods.

IT am a Nascom 2, Gemini 64K RAM card, GM829 FDC and Gemini IVC user. [I am running CP/M 2.2 with Pertec FD250 drives.

I purchased surplus Pertec drives from the USA and had lots of problems. All the problems were a result of leaky decoupling capacitors. For those of you who intend to purchase surplus FD250, I suggest that all the decoupling capacitors should be replaced. Other than this, the drives are great.

There is a simple hardware and software modification to get these drives reading and writing 40 tracks instead of 35 tracks. Though I have done this independently, I understand "Henry’s" is offering this modification. For those of you who are interested, please write and I will send full details.

Those of you who intend to make the printer-buffer as published in the June 1984 issue of BYTE, please note that the PIO output of the Nascom 2 or Gemini should be buffered and properly oriented with pull up resistors before it will work. I assume that the readers will have taken care of the other errors in the buffer hardware and software as published by BYTE

All correspondence on the above and other Nascom/Gemini subjects welcomed.

Yours truly, Hiten Patel, 4 Navyug Sagar, 183 Walkeshwar Road, BOMBAY 400 006, India.

Further thoughts on Hisoft Pascal

Following on from the random musings of Dr. Dark in the issue of July-August 1984, I am writing to tell of some procedures developed for just this need. The CP/M manual describes a file control block (FCB) which is used for random access, but this is not allowed for in the standard Hisoft Pascal file handler – the Pascal one is three bytes too short. So we want a definition of a FCB which can be used for random access, like this –

TYPE charll = ARRAY[1..11] OF CHAR;

{ charll is for the use of routines manipulating filenames unlike the Hisoft filename it coes not contain the : or . which are displayed in the directory listing so that a file will be filenameext and not filename.ext }

febtype.= RECORD

DRIVE CHAR; NAME : charll; EX : CHAR;

$123 : ARRAY[1..3] OF CHAR; DIRECTY : ARRAY[1..16] OF CHAR; CREC : CHAR; RNDREC : INTEGER; RNDOVF : CHAR END; VAR { whilst we are about it we can create three (or more) of the FCB’s so that we can use more than one random file at a time } HEADER : ARRAY{1..3] OF fcbtype;

The other definitions of types and variables must be placed in the program as needed. The most important of these is a buffer area to store the record read from the file or about to be written to it. The simplest of


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