Getting electrocuted

Have you ever experienced an electric shock? I have. many times. I guess being the son of an electrical engineer fed my interest in powered toys and my education led to the same type of career but my first shocking memory is of being put to bed in a spare room while my parents were visiting friends. I was probably four or so and I was mesmerised by the empty socket for the reading lamp above the bed. Naturally I stuck my finger in it and received 240 volts across the tip as I shorted the bayonet mount contacts. This was a shock in all meanings of the word and resulted in a burn.

We’ve all put our tongue across the terminals of a 9V radio battery haven’t we? I made a lot of electronic toys with triacs that bit and capacitors that discharged through me. Then I was employed repairing adding machines and computers with all kinds of high voltages or large currents. I once watched as a colleague used a spanner to loosen a bus bar from a large capacitor bank in a system which had been turned off and disconnected but not discharged. As he shorted between two bars the spanner disappeared literally in a flash right in his hand. Amazing.

Another time I was present when a switchboard I had assisted to wire up was tested with very high currents. It had 3 phase power running through copper bus bars 6mm thick and 10cm wide but we had forgotten to install the plastic insulators between them. As current flowed the electric fields caused the bars to bend and touch. There was another flash and when we opened the cabinet there were no bus bars to be seen but the entire inside surface of the cabinet was copper plated. Impressive.

A shock between one hand on a 240 volt connector and the other hand on a good earth is like being kicked in the chest by a mule. Trust me. A shock through your arm or fingers will cause the muscles to involuntarily contract very quickly. I was once standing in a factory next to a guy who did just this while holding a screwdriver. He unintentionally flung that tool straight up with such force that it was embedded in the roof some 10 metres above.

My favourite occurred while I was adjusting the picture on a video monitor from behind while the young lady at the keyboard provided feedback on height, width, pincushion etc. I touched the high voltage going to the crt which was about 12,000 volts but with no real dangerous current capability. I grunted and pulled my arm out instantly but the real shock came when the girl screamed and leapt to her feet. I don’t know what I thought but I screamed with her and the whole room full of operators screamed with us. Then we all had a great laugh.

Most modern electronics is low voltage and safe but I am sure there is still time for me to stick a finger somewhere I shouldn’t in a washing machine or something. With a name like Sparkes it is almost inevitable.


Which way is up?

Yesterday we were having breakfast in Marcoola when Carol said how nice it is to ‘come down the coast’ and then quickly corrected herself to ‘up the coast’. She was referring, of course, to the fact that we were north of home. From Brisbane, ‘down the coast’ means the Gold Coast, that seething den of drugs, vandals, violence and tourists whereas ‘up the coast means the Sunshine Coast, the bright, friendly strip of sun-washed beach towns. ( I hope my geographic bias is not showing.) However, since Brissie is 10km inland and up-river it is actually downhill in either direction. As John Masefield said:

I must go down to the seas again, to the lonely sea and the sky,
And all I ask is a tall ship and a star to steer her by,

There is no mention of north or south here. Who decided that north is up and that all maps should be drawn that way? Was there a worldwide convention at some time that reached such an agreement? I have read that the Chinese may at one time have felt otherwise and that the word ‘north’ is derived from the German ‘nor’ and the earlier ‘ner’ which actually means ‘down’.

If someone had decided to paint the south pointing half of a compass needle red instead would everything be different? On further rumination I have decided that since the majority of early astronomers lived in the Northern Hemisphere they probably noticed that the stars seem to revolve around a point in the sky which probably seemed like a good start to navigation.

Here in the south in Australia, previously Terra Australis which means Land of the South, we have had an indigenous population for 30,000 years. Much of their art consists of abstract representations of their homeland in the form of maps or aerial views. I wonder whether they are oriented with north upwards. Does anybody know?

In the meantime, as Canned Heat once sang, I’m “Going up the country.”


tramsThe Power of Spin

I was looking at my ipad recently and reflecting on the advances made since I started in I.T. Many people have written about the processing power in a digital phone versus the processing power available on Apollo 11 which took three men to the moon but I am interested in the mechanics behind bulk storage. My tablet has 8GB in a few square millimetres of silicon. My mainframes used to have great rolling disk drives with platters bigger than your barbecue.

I remember an incident back in the 70s (that’s the 1970s) on a cold Sunday in Melbourne at the old Gas and Fuel Centre in Collins St. That was the pair of rectangular buildings you see above which have long been demolished and replaced by Federation Square. We were updating a Burroughs B7700 system to a B7800 system and this morning we were installing the processors. Each CPU was a cabinet about two metres tall, three metres long and sixty centimetres deep and weighed about a tonne. Today the equivalent would be about a square centimetre I.C.

They were too big to come up the lift to the third floor so they had to be lifted by crane and come through a hole where some windows had been removed. Unfortunately, there are trams in Flinders St and as you can see from the photo taken a few kilometres away in St. Kilda, there is not much space between the overhead wires. These wires are at 600 volts DC and can carry enough power for a network of heavy trams so you don’t want to touch them with your jib. We had to negotiate with the city council to have the Flinders St trams shut down for two hours! We then powered off the entire computer room. (Almost an entire floor of the building on the right.)

When the time came to power up the system, I started with the disk drives. Now I want you to forget the 500GB disk buried somewhere in your laptop or even the $200, 4TB external backup drive you may have picked up at Dick Smiths or Frys. These were subsystems consisting of a controller and eight disk cabinets. Each cabinet housed four disk platters on a common spindle rotating in a vertical plane. Each platter was about 6 – 8mm thick and about a metre in diameter and quite heavy. At speed each platter had hundreds of read/write heads pushed within nanometers of the surface by compressed air and they were sealed and pressurised through the most amazing set of filters. Each track had its own head hence the term “head per track” disk. The entire cabinet contained 5MB of storage. That’s not a misprint – that is FIVE MEGABYTES. That would hold maybe one photo from a high def smart phone camera today and it cost hundreds of thousands of dollars. Anyway, Gas and fuel had four complete subsystems. (32 disk cabinets)

When you hit the ‘on’ button on a subsystem, the first disk drive would slowly begin to come up to speed. Given my marketing background and the title of this BLOG entry you probably expected a different type of spin eh? After about two minutes when the disk is nearly at maximum speed and the current draw is reduced it would automatically start the second disk in the string and so on. You can imagine that it takes a long time to get them all going. I decided to shortcut the process. I powered up each system as fast as I could walk between the controllers so that I had four coming up together. It would have made a good movie scene from Frankenstein’s lab as the deep throbbing noise and vibration began to shake everything. As the pitch started to rise there was a sudden thump and it all began to spin down. The lights flickered off and on and then the noise of the disks died away to be replaced by other distant sounds. I had dropped power to the entire building, all eleven floors. Lucky it was Sunday!

Being a gas company, G & F had installed two gas turbines on the roof to supply backup power and they sprang into action although crawled might be a better description. They were spinning up almost as slowly as the disks but with much more drama. It sounded like a 737 landing on the roof. Being aware of the lag in starting gas turbines, they had also installed two diesel powered generators made by International Harvester. (Remember them?) These diesels were kept warmed by electric sump heaters and could literally spring into action reaching full revs in way less than one second. Not fast enough to avoid bedlam in the computer room but boy was it exciting. Being responsible for all this made it very, very exciting for a young technician like myself. It turned into an extremely long day but was quite a learning exercise with regard to electric power sources.

Today, I can turn on my ipad and have it alive in a flash with more processing power and storage than the entire glass house we have been discussing. It runs all day on its internal battery with no moving parts and the trams are safe.

Tell all this to the kids of today and they won’t believe you. (Monty Python)(needs Yorkshire accent)


Australian_Coat_of_Armspre-fed coat of arms

Recently I was watching Bill Hague, the British foreign minister, on TV and he was speaking from a dais decorated with the British coat of arms and it started me thinking. The Aussie coat of arms has a kangaroo and emu on each side of the shield which contains the badge of each of the six states. The shield propper uppers are probably the best known unique native animals. 

The British coat of arms by contrast has a lion and a unicorn propping up the shield. A lion? When was there last a lion in England? Apparently it is a reference to King Richard known as the lion-hearted, it’s a bit like a football team emblem. The unicorn is meant to represent Scotland where unicorns once ran free. It is chained up because as everyone knows, free unicorns are dangerous. The shield has four quarters (How many quarters can you have?) with the English lions, the scottish lion, the Irish harp and then – the English lions again. Do I detect bias?
I started to wonder about the symbols of other countries and whether there was more humour to be mined. The U.S.A. has the “Great Seal” rather than a C of A. It shows a bald eagle holding an olive branch and a bunch of arrows balancing peace with war. There is a strong representation of the 13 original colonies but no reference to the current 50 states – maybe that is a number in flux. There are 13 stripes on the shield, 13 stars above, 13 leaves and 13 olives on the branch. Interestingly the stripes have the white on the outside unlike the flag which has the red on the outside. The back of the seal is the weird pyramid with one eye as seen on the dollar bill. There have been reams written about what this might mean so I will desist.
The German C of A is a simple black eagle on a yellow background. Pretty simple. But the old Imperial German one had a near nude wild man on each side. Kinky! The French don’t have a current coat of arms but the old one was a bunch of fleur-de-lis on a blue background. I have no idea what that represents which is typically Gallic. Monaco’s is a hoot with two monks holding swords. Apparently the monks invaded Monaco in 1297 hiding swords under their cloaks. And we thought the modern church had issues!
The Russian C of A is like the U.S. eagle except it has two heads and instead of the olive branch and arrows it holds an orb and a sword, symbols of power and control. The Mexican arms also have an eagle but this time it is sitting on a cactus and holding a snake in its beak. It is said to represent the victory of good over evil though this may be an evangelical interpretation of older Aztec traditions. Poland’s C of A has a white eagle with gold beak, talons and crown.
There is a trend here. Eagles. What is it about eagles? If not eagles it is lions. There is something about the choice of animals that transmits feelings of power, strength and grace. In this context the cute kangaroo and emu seem a bit tame but perhaps they are a true reflection of the Australian psyche.
Since writing this about a week ago I have admired the beautiful carved coats of arms on the old customs house next door. But they are different!  Of course, the building went up before Federation so there could be no representation of the states – they did not exist. Apparently there was a generally accepted but not official c of a which failed to comply with heraldic tradition. The shield contained symbols of Australia’s four main industries; transport, grazing, agriculture and mining. It is pictured above. Today, a similar approach would require symbols for banking, higher education, welfare and maybe still mining. ( for now)

Fire in the hole

How do you put out an electrical fire? I can imagine you struggling to remember which extinguisher has the black label and whether you want powder or foam or just a fire blanket. Well, in my illustrious and long career I have seen the evolution of fire-fighting in the glass house, the big computer rooms, and the stories have been hilarious. I stress here that I have never actually experienced a fire in a computer room but the near misses and false alarms make, I hope, interesting reading.

In the beginning there was CO2. (Carbon dioxide) This gas is inert and is heavier than air so it can settle on a fire, displace the oxygen and starve it to death. Unfortunately is is also deadly to humans. It can asphyxiate you at concentrations as low as 7% whereas fire flooding systems use up to 30%. A fire alarm in a CO2 protected glasshouse meant quick evacuation. I was present in the computer centre of my old alma mater when smoke from a bad servo motor in a tape drive triggered a fire alarm in computer room ‘A’. The computer centre was divided into two rooms, each with a large mainframe and associated peripherals and with separate power, cooling and fire protection. Within seconds there were deafening bells, a hurried power down of everything and a lightning fast evacuation. Then we watched and waited. Finally the CO2 went off. It was spectacular, particularly as it went off only in computer room ‘B’. Oh well’ back to the drawing board.

Then there was halon. Short for halomethane, this family of compounds react with flames to chemically quelch a fire. This allows them to be effective in a flooding environment at concentrations as low as 5% and they can be safely breathed by humans, even computer operators. It seems like a perfect solution but there were some problems. Firstly the small amounts required allowed high pressure bottles and when released it was almost explosive. I attended a system at a pharmaceutical company just after a fire alarm where where the halon was released beneath the raised floor. All the floor tiles had jumped about a metre and landed everywhere. It left a steel support grid about two metres above the concrete sub-floor which would have made it impossible for anyone to move about fighting fires or doing anything else. There was no fire.

Another problem with the huge pressure change on release is the accompanying temperature drop. This effect is the basis of any air conditioning system but when ice cold halon meets hot running computer power supplies the results can be devastating. I have seen a fine mainframe almost wrecked by this and requiring weeks for repairs.

Aside from these issues it turns out that releasing halon gives you sunburn. Indirectly admittedly but, like freon, the released halon rises to the stratosphere where it reacts with and destroys the ozone layer. (So they say) So halon disappeared as quickly as it had appeared.

Do you know what the current preferred fire fighting compound is for computer rooms? H2O. Yep, water. Sprinklers are easy to install and manage, the water lowers the temperature of any burning compound and quickly puts out a fire. In the mostly low voltage environments of large computers it doesn’t even cause short circuit damage and it turns out that most people power a computer off when they hear a fire alarm, either manually or automatically. Once you dry out the system there is not usually much damage to repair. As an example have you ever dropped your mobile phone in your swimming pool? I have. Open it, leave it in the sun for a day or so and “hey presto” all good usually. Coffee in your keyboard? Try soaking it in your kitchen sink with the dishwashing water and then air dry thoroughly. It often works.

One last fire related anecdote that still irks me after about 25 years. We had a small system at a major library which also had a Fujitsu system back when they were known as Facom. There was a fire in a nearby room and all the computers were engulfed in thick, acrid smoke all day while the fire was fought and beaten. We spent a week dismantling, cleaning and polishing all the disks and generally washing everything. We were very proud to have restored the system and made thousands in maintenance revenue. Our Japanese friends did not bother. They just wrote off the system and used the insurance payout to sell the library a new one. Several millions in revenue. Bugger.

I hope you never have to face a fire yourself.



I keep hearing that cars are becoming appliances. Performance cars are too fast to be used anywhere and luxury cars are unaffordable so we all drive appliances to and from work and, just like kitchenware, they are mostly white or silver with the occasional black.

Perversely, fridges are becoming more like cars used to be. They come in stereotypes depending on origin. For example, if you can hang half a carcass along with eight slabs of beer it is probably American. If it scans barcodes, keeps inventory and orders refills over the web it is Korean or Japanese and if it is colourful and stylish it will be European. If it’s white, noisy and goes forever it might be an Aussie.

A trend I have noticed lately is bloke’s fridges. These come swaddled in denim or deer hide or just painted in your team colours and they are meant for the ‘man cave’. They hold many cans and bottles and there is no shelf for quiche. My question is, “What about the girls?”.

I don’t subscribe to the convention that women belong in the kitchen and I can fry bacon sandwiches as well as anybody. Why are there no fridges for the room dedicated to the lady of the house. I’m not necessarily suggesting pink ribbons or quilting but has anybody thought this through? And why is the man cave also known as the sports bar or game room. Of my acquaintances most of the actual sporting activities are carried out by the WAG. I have female fiends who run up mountains or compete in triathlons or marathons. Most of my male friends have bad backs or crook knees and prefer to sit in a soft recliner with a cold beer watching footy or cricket on a half-hectare Television.

Oh, I just realised that I have answered my own question!

P.S. WAG = Wives and girlfriends.

Long Term Archive IX

What media will you use to store your everlasting data? We have discussed the issues with keeping the spinning brown
stuff (Disks) going due to mechanical issues. We have also mentioned the chemical decomposition and coercivity decay of magnetic tape over time. I have admitted my predilection for physical records that do not require fancy technology to recover so I like rock paintings, engravings and ink on paper. It is difficult however to balance the convenience of storing a terabyte of data on a half kilo, two hundred dollar disk drive with the mountain of paper required for the equivalent in written pages. (Approximately five hundred million pages)

Back in the nineteen nineties some guy tried to market a system which converted data to a 2-D barcode which could be printed on any printer. It could be photocopied or faxed and it could be input as data again by a simple scanner and some software. It stored 4MB on one A4 page. That’s about the same as two thousand typewritten pages. I really liked this but it never caught on. Even so, you would need two hundred and fifty thousand such encoded pages to match the aforementioned hard disk. (1TB)

This brings me to the optical disk. CDs, DVDs and Blu-Ray have tiny physical pits which are read by a laser and although the players might be obsolete or just worn out in the future, the pits should still be there even if the Martians have to read them bit by bit through a microscope. Of course the encoding is digital and it is not just zeroes and ones but a special code (Atkinson code) to eliminate strings of the same bit. Someone could work it out.

You may have heard of CD rot or the discolouration of early CD plastic due to oxygen getting in. The gold CDs were less vulnerable to this than the polished aluminium substrate examples but it has all been solved with an epoxy edge layer. Anyway, it only applied to pre-pressed commercial CDs and DVDs such as music and movies. Your own data goes on CD/DVD-R or -RW which use dyes and the manufacturers assure us they will last for 100 years.

Still, 100 years is not that much. Imagine if the oldest recorded history we had was news articles on the Wright brothers flight or ‘House Rule’ being accepted for Ireland or turning of the first sod for Canberra. I’m still waiting for the next breakthrough technology in long term storage.