80-Bus News


January–February 1984, Volume 3, Issue 1

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Lucas Logic apparently have lost their commitment to Nascom Microcomputers and products. Their relationship with Dealers is appalling.

The sooner Nascom is bought by a decent company the better. In my opinion in their hands Nascom is dead.

Yours in extreme anger and disappointment,

Dr D Plews, MB ChB, Keighley, W Yorks

Rory a Sadist?

Whilst reading Rory O’Farrell’s article “Happy Talk”, I got the impression that he is some sort of sadist. The time taken to load a file into a disassembler, save it into 4K blocks as a hex file, then finally to transfer the file, must be a least 10 minutes per block.

For some time now, I have been working on a quick and cheap data transfer program for the home enthusiast. The transmitting of data is done via a BASIC program which reads any file type and transmits via the serial port. For reasons mentioned in Rory O’Farrell’s article, the program cannot transmit pure binary object code, it is therefore necessary to convert the file to some form that may be recognised by PIP and not to send it Control Zs. The file is received on the second machine via the RDR: into a file. A small BASIC program is then required to convert the program back into its binary form.

Finally, a little tip for NAS­COM CP/M users using the AVC board. When most people boot-up CP/M they type AVCTXT straight away to give an 80 column screen, or modify the BIOS via the config program to execute a file AUTO.SUB. You then create the file AUTO.SUB and enter the command AVCTXT.

Have you ever wondered why it takes 15-20 seconds to execute AVCTXT after boot-up? The reason is simple, when Auto load is specified, it sets a jump in the BIOS, the address jumped to is to load SUBMIT.COM, it is then the job of SUBMIT.COM to load AVCTXT and execute it, therefore, taking time loading two files to achieve one goal.

Pondering on this, I decided to delve into MOVCPM. I found the bytes which loaded SUBMIT.COM and changed these to AVCTXT and resaved MOVCPM. CP/M now boots-up AND executes AVCTXT in less than 5 seconds. The trick is:

– D 0A00
            Notice that locations 0A08 – 0A17 contain SUBMIT AUTO.
            Change these locations to the following:–

     0A07            – This is the length of the command to be executed
     0A08 41 A
     0A09 56 V
     0A0A 43 C
     0A0B 54 T
     0A0C 58 X
     0A0D 54 T
     0A0E 2E

MOVE 55 *
SOURCE (press enter)

Yours faithfully, P.A. Dutton, Northfield, Birmingham.

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