Welcome to the Highlands Cottage Computer Center Web Site at www.hccc.org.uk.
This is Nick and Dom Glazzard's "vanity" site and it should probably win
an award for being almost 100% useless...
Nationalism is a curse ... but there are a couple of waving flags above anyway ... purely as a
clue to the nationality of your "hosts".
Our site's name - Highlands Cottage Computer Center (HCCC) - harks back to
a time when computers were so expensive and comparatively rare that organizations
tended to gather them together in one place, which served as a central resource
for everyone who needed computing facilities. There were a lot of bad things about
this, but also some good things.
Since HCCC has many computers from the very new to the fairly ancient, used
for both work and play, and since most of them are gathered in one small room, its not
an entirely inappropriate name. Although, since we no longer live at Highlands Cottage,
it is nowhere near as appropriate as it once was! Once you have a domain name, you
are sort of stuck with it ...
For eleven years -- between 2007 and 2018 -- this website was served up by a Digital MicroVAX 3100-95
running VAX/VMS with the WASD web server.
It never skipped a beat and still works perfectly. However, the server was at the end of an ADSL line
and that inevitably made it quite slow. There is also now a need for more geographic flexibility -- mostly accessing
e-mail from a web client, which I didn't want to set up on the VAX. So as of June 2018, this site and associated e-mail
services are hosted at Vision Internet. It was a painless transition.
I have also divested myself of all the "big iron" test equipment for which I wrote the GPIB based
control software described in some of the pages here. This includes the Z3801A GPS DO, so the pages
related to that ("precision timekeeping") have been removed.
The equally "big iron" Studer and Revox audio equipment has all departed too. I occasionally regret that, but time
marches on, and they are probably better off with their new owners.
... is mostly over at ... Facebook ...
Below is a list of topics. More will be added from time to time.
Many of them are pretty esoteric and are likely to be of very limited interest. But you never know -
there might be something useful or of interest to you.
As everyone knows, there is so much "stuff" out there on the Web. Vast ... overwhelming ...
endless ... 😃 There
doesn't seem much point in repeating any of it, so only "unusual" things are here, for the most part.
More bizarre than unusual in some cases, perhaps!
These pages try to stick to technical things of some substance (hopefully). Some opinions creep in here
and there ... but not too many. Why is this not a blog? Even though blogs are pretty flexible, I
prefer to express my ramblings independent of the influence of any third party organizational tool.
I accept most of the arguments presented in Jaron Lanier's excellent "You are not a gadget" where these
matters are concerned.
Also, blogging software probably doesn't run under VMS! 😃 This website is also totally static,
using just HTML in ways that were no doubt "deprecated" decades ago ... but I just don't care ...
Repairing a Sony ICF-SW100 Radio
Pre 1997 ones will die of broken ribbon cables. It is inevitable.
Repair kits seem to be no
longer available. Desperate times call for desperate measures...
ReVox A78 Amplifier renovation
A fine amplifier. My E-Bay purchased example needed some TLC, though. It is used
heavily on an almost daily basis.
The Recorder-Reproducer Interface
A totally over-the-top specialized sort of pre-amp for use with recording
devices (especially professional analog tape machines). It took 5 years to
complete... But I learnt a lot! I haven't finished writing a full description
of this, but maybe one day I will.
Circuit Diagram Symbols Library for Inkscape
A Python program that writes an SVG symbol library for use in Inkscape is
here. The result of running that is here
(save the linked file to disk as something.svg -- just clicking on it will show a blank page).
Nothing wonderful, but at least it works as a proper symbol library in the latest version
of Inkscape (V0.91). The SVG file needs to go in
The S-2020 Audio System
A DIY audio project that replaces the source components and the pre-amplifier/controller that I had been using
up to Spring 2016.
There is nothing new here, but it might be another example for people thinking of going down the DIY audio route.
[NOTE: This page was previously generated by pdf2htmlEX from a PDF file created with LaTeX. It was a bit of an
experiment in many ways. I went back to a more traditional approach converting LaTeX to HTML with tex4ht (modified).]
A (large, 33MB) PDF version of this is here
Electronics? Computers? A bit of both.
Controlling GPIB Instruments from Ubuntu Linux
A way of keeping that unruly test and measurement gear under control using
your Ubuntu Linux laptop and an Agilent USB/GPIB interface. Maybe of some use to
people who want to do that sort of thing.
Controlling a Rigol DS1052E Oscilloscope from Ubuntu Linux
Some software to control and read waveforms back from a Rigol DS1052E oscilloscope.
It would probably work with other DS1000 scopes and may be a starting point for interfacing
with other Rigol devices. This is an example of using the USB Test and Measurement Class
support built in to Ubuntu Linux.
Using a Measurement Computing PMD-1608FS with Ubuntu Linux
Some software to control a USB data acquisition (and digital i/o) device.
This is pretty specific to this particular device! Since this code uses some third party
GPL 2 licensed material, it too is GPL 2 licensed (unlike my other code here, which is MIT
licensed or public domain).
Negatives in to Positives: Fun with a cheap transparency scanner
A Python program that can convert raw orange scans of negatives to decent looking positives.
On a good day, anyway.
Simple Dust Busting: Cleaning up white dirt on scanned negatives
Describes one simple way of removing dirt (hairs and other grot) that appears white on scanned
negatives after they have been made in to positives. Includes a mixed Python and C program that
implements the method.
GTerm: A dumb Telnet terminal with colour graphics and APL support
All written in Python (with PyQt, PyOpenGL and lots of other stuff). I did this mostly so I could
do interactive graph plotting and use APL on an emulated CDC mainframe computer, but it was an
interesting exercise in many ways. I doubt anyone else will find it useful as such, but some not
very well documented features of various technologies (such as option negotiation for usable Telnet
sessions with the Python Telnet module) are explained (somewhat) in the code, so it might help
someone. It works on Ubuntu Linux and Mac OSX Mavericks. Porting it to Windows would not be
totally straightforward (due to how it uses select()).
Control Data Corporation is, perhaps, largely forgotten these days. It built the fastest
computers on the planet for the best part of two decades, however.
Innovations in CDC Mainframes
Control Data Corporation computers introduced a lot of important innovations way back when.
Some highlights are described here.
A Ray Tracer for CDC Mainframes
A newly written (well, 2005) application to run under CDC NOS. For the very few people running
CDC NOS ... Not recommended for general purpose ray tracing on today's machines!
U.L.C.C. in the 1970s
The University of London Computer Centre (ULCC) was established in 1968 to provide a central
computer service for the University of London based on CDC mainframes. Here is some
information about ULCC in its "CDC Era" which ended around 1982.
My Audio Systems Through the Ages
An illustrated trip down memory lane, eventually coming almost --- well, not very --- up to date.
There were major changes starting in Spring 2016 which are not in here.
Fun with Pink Noise and Rooms and Loudspeakers
You should ignore this! Go to Siegfried Linkwitz's site instead.
In fact, I now believe that the sort of "room correction" described here is a waste of time.
I respect the opinions of those who think otherwise, though. I'm also no longer at all sure
the next sentence is true, either ... 😃
Usually, the factors that affect how reproduced audio sounds are, in decreasing order of
importance: (1) the room, (2) the loudspeakers, (3) everything else ... oh ... and, quite certainly,
(0) how the recording was made in the first place. Here are my
naive attempts to understand what my living room is doing to sounds from my speakers and
to improve my listening experience in the light thereof. This topic gets very complicated very
fast, and I've only scratched the surface. This page has gone through several iterations as
I have read and learned more. The current version covers a lot more than I had originally
intended, including some semi-philosophical thoughts on what sound reproduction systems can
and should do. Apologies for the length and variety of topics covered (they are all closely
related however). A direct link to my summary of what real experts have concluded (and what
they disagree on) is here. My musings on what audio systems can
actually do (and what they do not do) can be found here.
Open Reel Analog Tape Machines
Why I find these dinosaurs interesting. Very interesting ...
Analog Audio Tape Performance
Some thoughts on the objective and subjective performance of analog audio tape recorders.
Audible and Inaudible Problems with Digital Audio
Things that are "wrong" with digital audio, including many things you can't hear. Summary: there is
fundamentally wrong with digital audio. Digital recording, in particular, is superior in every way
to analog recording, although analog recording can be excellent and has its own "character".
Recording to analog tape may force working practices that lead to a better overall musical outcome
A Funny Thing Happened on the Way From the D/A Converter ...
Large amplitude ultrasonic signals from a consumer soundcard ... most curious.
How AC Bias Really Works (Maybe)
An attempt to explain the process that transformed magnetic sound recording quality from pretty
dreadful to excellent. It isn't simple. A straightforward computer simulation helps explain it ...
up to a point. A PDF version of this is available here (this is part
of the unfinished Recorder-Reproducer Interface documentation). The equations are more
readable in the PDF document, but you miss out on the animated GIFs!
An Audio Slide Rule
Build your own slide rule to show the relationships between some audio quantities. Sticky backed
plastic and cardboard may come in useful ...
Servicing a Revox A77 (Dolby) Tape Machine
Information on repairing and lining up one of these beasts. They are still capable of really
good results and there is no shortage of spare parts to maintain them. The "Dolby" version has
some additional complications, though ...
Revox A77 - 41 Years Young
Seven years on from the repairs described in the above link, another problem surfaced.
Once that was fixed (not too hard) measurements show that the machine is pretty much as
good as new. Wow!
collection of links to other audio related sites, somewhat skewed towards Studer/Revox
enthusiasts. Many sites are in German, so Google Translate may be your friend (well, sort of).
Vintage Technical Articles
Studio Sound June 1977 - The Centenary of Recording Sound (73MB PDF file)
A set of (perhaps surprisingly) erudite articles on the history of recorded sound. The coverage is both
broad and deep, with some material I haven't seen anywhere else.
Some Articles by "Cathode Ray" from the early 1970s (13MB PDF file)
"Cathode Ray" (M. G. Scroggie) wrote a long series of articles on fundamental topics in
electronics, published in "Wireless World", starting in the late 1930's.
In my opinion, his writing is extremely clear and entertaining. Quite exemplary, in fact.
The link above is to a few random articles from
copies of "Wireless World" I happen to have.
For a more complete collection, his books: "Second
Thoughts on Radio Theory" and "Essays in Electronics" are sometimes available second hand
(e.g. via Abe Books). I cannot recommend these too highly --- most of the subjects he deals with remain
very relevant (the laws of physics don't have an expiry date).
A much better collection of his articles than the one at this site
can be found at: www.vk6fh.com
Douglas Self's always excellent site includes several "Cathode Ray" articles in his
"Wireless World Archive" section.
Keith Snook's site
has another excellent collection of "Wireless World" articles, many written by "Cathode Ray".
In the late 1980s another "Wireless World" author followed in the footsteps of "Cathode Ray".
He (presumably "he" ... could be "she") went by the name of "Joules Watt"! They wrote a number
of interesting pieces. Below you can find three of these articles, which are a pretty good read ---
although maybe not as good as "Cathode Ray"'s (no offence intended!).
Maxwell's E. M. Theory Revisited (5MB PDF file)
A fair introduction to Maxwell's equations. Some parts of the introduction may seem a little
strange ... why is Maxwell's theory about to be replaced? Well, at this time there were several
very vocal individuals bombarding "Wireless World" with letters expressing the opinion that
conventional theories of electromagnetism were all bunk. They particularly disliked
displacement current. It didn't end with Maxwell, by the way. They hated relativity even more ...
in fact they hated all of modern physics! All very odd indeed ... This article was one of several
aimed at responding to this nonsense.
All About Curls and Divs (9MB PDF file)
A fair introduction to vector calculus, written as a follow up to the above article.
Logs Again (5MB PDF file)
Sort of about logarithms. But also sort of about Bode plots. I'm not so sure about this one,
to be honest...
"Pioneers" by Tony Atherton
Also from the late 1980s "Wireless World" is this series of articles about people who made key discoveries
or made real progress in understanding electricity and electronics. I don't have the full set, unfortunately.
They are rather good, I think.
How Electricity is Made and Transmitted (25MB PDF file)
An excellent pamphlet from 1980 published by the Central Electricity Generating Board.
It does what it says on the tin. I got this at a local boot fair in 2012 for 20 pence.
Fourth International Congress on Acoustics, August 1962 (6MB PDF file)
The third paragraph of the section entitled "Psychological and Physiological Acoustics" describes an experiment by
a Dr. D. L. Pimonow of the French "Centre National d'Etudes des Telecommunications" which is yet another that
purports to show that the ear can detect the presence of filters in a signal path far beyond the known frequency
of audible sine waves. In this case, a 45kHz low pass filter was detectable. The loudspeakers (ionophones!)
and amplifiers had
a "pass band of 100 kc/s", and the test signal was a train of 5us pulses at 2Hz, every second of which was
filtered, with the other untouched. The subject adjusted the amplitude of the filtered signal until it sounded
the same as the other signal to them. No doubt there are many factors that might be involved, but it is another
example of these sorts of things that I came across quite by chance. There seem to be quite a lot of them, over