Having fun at a classmate's expense and then the revenge of the polony.
In the late 1970s, I was doing my training at the Posts and Telecommunications Engineering College in Rhodesia (it is now Zimbabwe, which shows you how long ago this was and how old I am…).
As part of our training we were required to strip and rebuild a Creed 7B Teleprinter, a mechanical marvel which was a sod to work on – adjustments were done with tensions and clearances and screws and locknuts.
The college had a room full of these beasts, which had been taken apart and reassembled by generations of engineering trainees. In the corner was a patch panel with connections to each sender and receiver – usually your own sender was patched to your own receiver and so (if you had everything right) what you typed on your keyboard came out on your printer.
One of our class was a young Irishman who I seem to remember was called Joe, but being Irish everyone called him Paddy. A friend and I had our machines working while most of the class were still completing their adjustments. So we thought we’d have some fun with Paddy. We patched my transmitter to his receiver and vice versa, and waited for him to start testing.
Eventually he had his machine together and began typing….RYRYRY which in the 5-bit teleprinter Baudot code is alternated 01010 and 10101 characters and thus probably the best codes to test with.
So I typed SASASA back to him. He did not pick up the slight delay in my return and looked puzzled and started checking his machine again. In the other corner my friend and I could barely contain ourselves.
After checking his teleprinter again he typed some more. And every time he did we would type something different. And sometimes type the odd character out of the blue. How he did not see us sniggering to ourselves I will never know. We were nearly wetting ourselves.
Eventually we took pity on him. The next time he typed, we typed back “You’ve been had, you daft Irishman!!!”
His response to us was not kind, but was tempered with the happy knowledge that his machine was in perfect adjustment.
And he got his revenge. The place in which we were staying provided us with sandwiches for lunch every day, however at least two thirds of them were made with lots of margarine and slices of a particularly vile kind of polony which we loathed, and hence threw them away. The next day he surreptitiously retrieved them from the bin and wiped them all over my car windscreen.
This story reminds me of when I was in college about 50 years ago. One of my dorm mates was convinced that ESP existed and decided to try some experiments where one volunteer would concentrate on a randomly drawn playing card and a second volunteer in the next room would try to "receive" the telepathic message. I rigged a simple telegraph where the sender would squeeze a little key concealed in his fist while the receiver would watch a miniature lamp blink: 1 to 4 blinks for the suit, followed by 1 to 13 for the value. Of course the "telepathy" worked perfectly, or nearly so with no errors worse than one card value. We strung our believer along for at least a day till we finally could contain ourselves no longer and revealed the truth.
Just as an aside, my classmates also got my VW beetle one day and "bounced" it between two trees that were around 3 inches further apart than my VW was long. They were in hysterics watching me trying (unsuccessfully) to make a 100-point turn to get out. Eventually they took pity on me and "bounced" me out again.
We had a lot of fun in that class....
All the above stories remind me of a funny incident that occurred to me some 30 years ago. Our company in India had a software development contract from a company in Chicago developing PABXs. We had one team developing code in India and another team testing and integrating the same in USA. In those primitive days of software industry in India, we did not have a computer or the target system to debug and test our code. Nor were there any email or fax facility. So we used to write the code by hand and our typist used to type it on those old typewriters. After proofreading the same we used to send these coding sheets to USA, where our other team used to enter the code into the computer, debug, test and integrate it into the target system.
One fine day, I had just handed over my coding sheet to the typist. After about half an hour my typist came with a winning smile on her face. "hey Prabhakar, look at this , the special sign you have coded. I had to over-type three different keys to get it right. Is this the one you have coded? "
I looked at my handwritten sheet and the typed sheet and could not stop laughing. While coding I had scratched some of the mistakenly written character and assuming that it was some special computer sign my typist had diligently tried to create the same thing on her typewriter!
Designers of embedded systems need to test and troubleshoot designs by looking at both digital and analog signals, and the analog representations of digital signals. ESC Boston is the place to see mixed-signal oscilloscopes in action.