Something not strictly Gemini related is the more recent Dave’s Law of Inverse
Requirements. Now a few years ago I got involved in the design of a database system
for document retrieval using microfilm, the earlier examples of which were written
for the Gemini, but it soon became apparent that business customers were far more
happy with IBM type computers, but that’s beside the point. Anyway, we rapidly
decided that five fields would be manageable and entirely adequate, whilst more
wouldn’t, apart from that, the required information would be on the microfilm, and
the database was simply a tool to allow access to it. We also soon found out that the
bigger the company the more fields they wanted. That figures, as always, some bright
sparks in the company decided that management information could be accumulated
in the databases, thus defeating the aim of the system in the first place as the
management info was on the film.
This is where the Law comes into play. It states that the larger the customer, the
more fields that say they require, but in practice, the fewer fields they ultimately use.
BAA wanted 13 fields – they insisted, and grumbled loudly when we asked, ‘What
for ?’. They finally agreed to give it a go with the 5 fields supplied, with the rider that
they would expect the number of fields to be expanded or they could sling it back
and get their money back. You guessed it, the database is still growing after 3 years
at 15,000 entries a month, using one field of 12 characters. Several other customers
have exhibited the same behaviour. Strange isn’t it ?
I read an article once about the Great Murphy and how his Laws affect
instrumentation engineers. The only one I remember was one about having
dismantled and re-assembled a instrument, there would always be one nut and bolt
left over. Any one who’s taken a car engine apart will know the feeling and will be
lucky if it’s only one nut and bolt. None the less, the corollary was that having taken
the instrument apart again to fit the missing nut and bolt, it will be discovered that
nothing was missing in the first place, and that the nut and bolt came from one of
the several instruments which was serviced yesterday. Oh I know, having dismantled
and re-assembled many disk drives in my time – the number of times that particular
Law has held true.
A couple of pages worth. Paul said don’t make it too long or he’d cut it, so I’d better
stop here with one passing thought. Today is Sunday, and this afternoon I have done
something nasty to my back. Having very painfully sat down at the computer, I now
can’t get out of the chair. My brother says it’s good for a couple of weeks off work,
and I guess the doctor will say the same tomorrow. But I’m on holiday next week.
That’s Murphy for you, why can’t I be sick in the firm’s time ?
Oh yes, the answer to the question of the day, simple – it can’t be done, it’s a
hardware problem !!