Sinclair Cambridge Programmable

OK, the news that Sir Clive Sinclair died today (RIP, Sir Clive!) caused me to remember that I have another Sinclair calculator in my collection, apart from the two I’ve already talked about (the Sinclair Cambridge Scientific and the Sinclair Scientific). It’s the Sinclair Cambridge Programmable. Yes, it can be programmed! And, just like the Casio fx-98 I talked about last time, it was licensed in the US to produce the Radio Shack EC-4001 (more on that in a moment).

Sinclair
Cambridge Programmable

I bought it some ten years ago now, for the princely sum of $80. However, apart from the initial “does it work?” test I did at the time (as you can see, it's a little "worn" and faded, shall we say), I never really got into playing around with it. A couple of reasons I suppose: yes, it’s got an LED display, so there’s the whole battery thing to consider; and even better, because of the power requirements a programmable calculator would need, it doesn’t use AAA batteries, but instead a chunky 9V battery. Which, in turn meant that Sinclair had to fudge a different battery cover that bulged out. Not a very lovable profile at all.

The back view: BULGE!

Of course, you could always use the extra cost Sinclair Mains Adapter as well so you didn't have to worry about battery life. (Aside: I wonder if I can find one...)

So, the usual 8 digit display (plus there’s a scientific/exponential display mode as well), a weird layout of 19 keys to be sure (it took me a while to work out where the decimal point key was), and – because it’s programmable – there’s a grand total of 36 program steps in a loop. Once you reach step 35, it’ll go back to step 00. Woot! Of course, since there’s no storage, you can only have one program at a time.

And writing those programs? Well, have a look:

Mortgage repayment program

Each of the 36 steps can have (essentially) a single keystroke. Even better, there’s just one storage cell for a saved variable (sto stores the current value, rcl gets it back). Programming this to calculate anything remotely complicated would be … time consuming.

Manuals

Luckily there’s a Program Library book with some 400 programs ready for you to type in. The calculator I bought on eBay didn’t have the official Sinclair version of this book, but instead had the Radio Shack version. (Aside: I just found the official version on eBay and bought it.)

And, no, although I enjoy programming, using this would have driven me up the wall. Back it goes on my calculator shelf.

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