29 May
2013
29 May
'13
6:39 p.m.
On 05/29/2013 01:28 PM, Tony Duell wrote:
I regard the QX10 as being one of the best CP/M machines. It's quite
solid design.
I always think of it as a bit 'cute' - CP/M machines should be in big metal
crates with backplanes and separate boards for different functional areas!
:-) From a design point of view it does seem well thought out, though.
At some point I need to take a look at my system, as it occasionally resets
itself (seemingly at random) - that may be a PSU problem, but could of
course be various other things, too. It's infrequent right now (maybe once
in a couple of hours of running) - perhaps too infrequent to make diagnosis
easy!
A word of warning. The video daughterboard can take either 16K
(4116-like) or 64K (4164-like) DRAMs, you need 16 of the same type. There
are 3 (or so) links to move, to chenge the supply from 12V to 5V, connect
tue extra addres line, etc.
Mine actually has '4164' silk-screened on the PCB for all the memory
locations (and does indeed have 4164's fitted in the sockets). It looks
like there are six links on the board; three are set for 64k DRAMs and the
other three set if using 16k ones.
Tez...It is just me or it looks like an Epson printer?
:oD The main CPU
looks just like a MX100 without the top opening! :D :D :D
LOL! I've never open one of the MX100s but I imagine it's the same
engineering quality!
I really like mine :) Did you fix yours? (it was
you with one that was
having problems, wasn't it?) And I _love_ those 1/3 height floppy drives (I assuem
you've examined one, the head psoitoner is a voice coil with optical
feedback, like a miniature RK05 positioner.
Yes, they're wonderful little things, but I do worry about how robust they
might be (and how easy it is to obtain* spares should one die in some
horrible way). I am tempted to disconnect them and run the data cable -
via a socket in one of the expansion bay positions - to a pair of external
half-height drives (also useful because it's a pain having to dismantle the
system to clean the internal drive heads every time a disk decides to dump
its coating everywhere)
* I'm not sure if the 1/3 height drives that Torch used in some of their
systems are the same - if they are, I possibly still have some of those in
overseas storage.
Yes, I was
having problems with it. Turns out it was an unstable PSU. The
problem was solved with a replacement PSU donation from Fred Jan Kraan of
the Netherlands. Fred is a member of this mailing list. Many thanks Fred!
AI am sure capacitors are easier to find than PSUs... I'm surprised he didn't stick RAM in the empty
sockets as soon as he
discovered them. :)
Tempting but naaaa... I don't generally try to max out machines unless
there is a reason to do so. Best save my limited number of RAM chips in
case one of my machines suddenly needs a replacement in order to work. (-: The reson is simple, once you know it (and it's
not in any of the
manuals. Pin 8 of the DRAMs changes from being a +5V lien to adress lien
A7. It's decoupled to gound by 16 (I think) 100nF capacitors for 16K
RAMs. If you don't remove these when doign the upgrade, there is a
ridiculous amount of delay on the A7 line, so addresses get mangled.
That's interesting... my board has obvious pads for a cap at the top end of
each DRAM, but no caps fitted in those locations (there do look to be
decoupling caps for the memory elsewhere, of course).
Fitting RAM in the socekts on the mainboard has no
gotchas AFAIK. Just
stuff in 4164s in sets of 8.
Yes, I don't see any *obvious* jumpers etc. related to this (my system's
got 256K; I think most of the ones in the US shipped like that). They're
4864's in mine.
cheers
Jules