2 Nov
2002
2 Nov
'02
11:18 a.m.
On Sat, 2 Nov 2002, Jules Richardson wrote:
Will,
TurboDos does not have an inbuilt multiuser capability - ala MP/M. It's
approach to multiuser is via a slave processor for each external user.
The slave processor could be either an external computer linked to the
master machine by serial, or whatever, and the number of slaves could
run as high as 32. Slave processors were also commonly additional
processor cards in a S100 box each of which was linked to an external
terminal via a serial link. In either case, the 'master' processor
played the role of manager of shared assets - disk, printer, etc.
Because of the processor per user approach, the response of the system
was little affected by user load. Nice concept and nicely executed.
- don
I came across a site today which provided more
information on this critter,
and as Fritz had suggested, it is indeed a TurboDOS machine.. I have a copy
of TurboDOS around, but I don't know if Philips used a custom version
or ?
no idea on the data front. Did TurboDOS have built in multi-user support
(I know nothing about it)? If not then I'd definitely think that the
version on> this machine was custom, as it has support for at least 4
if not 5 terminals in its current state. That's just going by the cables at the back;
there's a lot of unused pins on
the card edge connectors, so given that the website claims support for 62
terminals I expect it could make use of some breakout box arrangment to give
more 25-pin terminal connectors.
Not to mention that I don't have a clue how
I'd copy it, or even what
TurboDOS runs on. Here's the link I found to the info on the P3800:
http://www.digidome.nl/philips1.htm
unfortunately I hit a bit of a snag with my machine. Following the flood damage
the previous owner had tried to fix the system. Trouble was, the machine has
two backplanes to it - the upper one with one row of card sockets and the lower
one with two rows. System cards from the top rack will also plug into the
bottom rack (which contains the PSU, mains voltage, and a spare slot for some
unknown board). The disk controller had been plugged into that spare slot...
:-(
It wouldn't have got any mains voltages but it would have got +5 and +12V on
all sorts of pins that it shouldn't have. I also found that the disk data bus
(SCSI? SASI?) terminators had been misaligned and so it's possible some of the
data lines were shorted together or at least had a low resistance connected
across them.
Curiously, the disk controller and the board the converts the system's
SCSI/SASI bus to MFM look to be identical on the P3500 (from the photos on the
website that Fritz posted about). So if one of those ever shows up, at the very
least it'd be invaluable for checking that the hard drive on this 3800 is still
operational - and in the absence of schematics for the 3800 it'd probably be
very useful for fixing the 3800's disk controller.
Also, the P4500 is a minicomputer of some kind,
apparently..
I'm not sure - I did a quick hunt on the web and there was very little
information around. One site seemed to imply that it was much older technology
than the 3800, but another site gave the impression it was much newer. Uless
the model number was reused they can't both be right :)
cheers
Jules
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