Scor­pio News

All Perversities

Now we all know the Law of All Perversities will contrive to make the most obvious obscure, take the instance of the Gemini with the faulty drive.

This was a GM903 (if I remember my Gemini model numbers correctly) a single floppy drive and a 5Mbyte Winnie. It came in with a dodgy disk drive, one of the Micropolis ones I think, they never were too reliable. Anyway, it’s a job of a few moments to replace the drive, and the Gemini was placed on the bench and the drive swapped. Because the keyboard and monitor were on the other bench, and the bench, as benches will, was cluttered up, having replaced the drive, the Gemini was moved to the other bench to test it. No joy, it wouldn’t boot from the floppy disk.

So back on the first bench, and the drive controller card was swapped. Back to the bench with the monitor and keyboard, and it still wouldn’t go. This process went on, the CPU card, the video card, the power supply – until the only thing left to swap was the case. Now cases don’t usually affect the operation of the machine, so we stopped to think – what had we missed ? In the end we fired it up without the keyboard and monitor on the work bench. It fired up beautifully – Oh heck ! Well I reckon you’ve spotted it. EM radiation from the monitor was being picked up by the disk drive, and all it would do was error all the time. Moral: put the lid on a Gemini before you try to run it near the monitor !

Diminishing Returns of Work

This exercise took two of us most of an afternoon, which neatly brings me to the next Law. Dave’s Law of Diminishing Returns of Work, which states quite simply that the equivalent effort visible from a group of individuals is approximately equal to the the square root of the number of individuals employed. This may be summed up by the equation E = √ I, where E is the equivalent visible effort, and I is the number of individuals. This of course gives the lie to the old school maths questions such as, ‘If it takes one man two hours to dig a hole 2 metres square and 1 metre deep, how long does it take the two men to dig a hole twice the size ?’. In this case the answer will be 2.828 hours and not as every school kid knows, 2 hours. Eat your heart out Kenneth Baker, try stuffing that in your National Curriculum. Whilst on about silly questions, ‘How may software writers does it take to change a light bulb ?’. Just to keep you guessing, the answer is at the end of the article.

Signetics WOM

Some years ago, BN, that is Before Nascom, I was the recipient of a pile of Signetics data sheets. When I riffled through them the first time, I saw nothing extraordinary about any of them. But on closer examination, my eye was drawn to the Signetics Write Only Memory chip. It looked odd, but the significance still didn’t sink in. Then