26 Jun
2005
26 Jun
'05
9:53 a.m.
On Sat, 2005-06-11 at 00:35 +0100, Tony Duell wrote:
I *still* haven't looked at this (car stuff took precedence over futzing
around with the Nascom!)
I have, however, found a few useful odds and ends relating to the Nascom
floppy drive board.
A3 schematic of the controller board (it uses an FD1793 or 1797 IC).
"Nascom floppy disc drive instructions" containing basic installation
routines. It mentions NASDOS, which was a 4K ROM-based DOS for the
Nascom 2 or 3 which provided disk utilities and program hooks. It also
says that DR CP/M 2.2 was available for the Nascom.
"Nascom floppy disc controller hardware manual" gives details of all the
links / pin assignments / IO ports for the controller board.
26 page overview of the NASDOS ROM - operation, disk layout, error
messages etc.
I can add them to the scan pile if they're not available anywhere
already. The quality on the NASDOS overview doc isn't up to OCR standard
really (think it's a fuzzy photocopy of a dot matrix printout to be
honest) but the others are all decent enough quality. I should really
check to see if I can find a copy of the NASDOS ROM first though (we
have a machine that should have the FDC board in it I think, but if it
was set up to only run CP/M maybe it doesn't have the NASDOS ROMs
fitted). Not much use scanning the NASDOS manual if the ROM no longer
exists anywhere!
cheers
Jules
On Fri, 2005-06-10 at 00:09 +0100, Tony Duell wrote:
I've now taken a look at that....
Initially I was puzzled. It makes no sense at all if the keys are simple
switches.... Tell me (as I can't get to my Nascom at the moment), how
many connections does each key have?
My guess (again) is that these keys are actually magnetic. There are 2
loops of wire trough a little magnetic torroid core. Pressing a key brings a
magnet against the core, changing its magnetic properties, anf thus the
coupling between the loops.
Each of the lines on the matrix in the schematic is a set of these loops
in series. Horizontal lines are the sense loops, vertical lines are the
drive loops. That would explain the cryptic comment on the schematics
that the order of keys in the matrix may not be the electrical order on
the PCB.
Alas I don't have a Nascom 1 schematic...
Well the Nascom 1 *keyboard* schematic is online on a Nascom site along