O.T. Sinclair Scientific


An early RPN calc was the Sinclair Scientific. Lots of key-bounces, high battery draining, limited math function and several more oddities. I used it for 3 years before I bought my 29C.

My Sinclair Scientific is still operationable, and I power it up once a while, just to trigger my nostalgia need!

Any else who used this calc?


If I am thinking of the same model you are talking about, it had a three register stack, which did not support copying values down the stack when you perform a binary math operation.

I bought the Sinclair Programmable from Galleries Lafayette in Paris in 1978 and kept it for a few years. I used it here and there. It was cute, but suffered from poor accuracy.



It only has a 2-level stack. In fact, it lacks an enter key, such that there is no way to lift the stack beyond the second level. It also lacks a degrees mode, such that trig arguments must be entered in radians and has only the common (base 10) logarithm. It even lacks pi, so conversion from degrees to radians is even more cumbersome. It works only in scientific notation mode, and the decimal point is placed implicitly when the exponent is entered. Finally, it has only 5 significant digits.

Edited: 7 Apr 2012, 9:42 a.m.


I had (and still have from my school days) a Sinclair Cambridge Scientific which was algebraic rather than RPN. It still works too!

At that time the Woodstocks were current but well out of my (and my parents) price league but I can remember drooling over the ads.

We weren't meant to use calculators at school (log tables and slide rules were the tools of the maths class) but we did, carefully translating our decimal trig results from the calculators back into minutes and seconds so as the teachers wouldn't know we had used a calculator (but looking back I'm sure they did).





I had the kit version of the sinclair. Think I paid les than $20 for the kit back then. I put it together and used it for a while until I got a much better calculator.

I still have a couple of the Sinclair Programables in their boxes with the several books of programs. I get them out every now and then to remind me how bad a calculator can be.



I had one for a (short) while but really didn't like it - replaced it with an HP31E (which I then sold to buy an HP33C)..

Mike T.


Oh, yes - I remember it well.

I built mine from the kit (GBP14.95, bought from ETI Magazine, which I later worked for) but couldn't get it working at first. It turned out that TI had supplied a batch of faulty clock chips - I discovered that mine would only work if it was cold enough. So I used to place in the freezer of the kitchen refrigerator, then set to work on my control engineering problems. Once I'd got the required calculations set up with pencil and paper, I would retrieve the calculator and set to work, getting as much done as I could before it warmed up and stopped working. Once the term ended, I shipped it back to be fixed, but only managed a few weeks more before realising I needed an HP.

The major problems were the 9V battery bulge, the three-level stack and - worst of all - the lack of X<>Y, which meant intermediate results often had to be re-entered. But it was a valuable introduction to the joys of scientific calculators!


--- Les



On the subject, I've always felt the Novus 46xx lines were lacking some of the very heart of RPN. For starters, I've never felt that a three-level stack was adequate.


That is only true for some models. Models like the 4640 and 4520 have a 4-level stack.


Thanks for correcting my technical glitch. Much appreciated.


It has only a 2-level stack. See my previous post above.


Once again, as above, thanks for correcting my technical glitch. Much aooreciated.

Edited: 7 Apr 2012, 2:07 a.m.


Ewww. It was even worse than I remember!


--- Les



Someone must like them as someone went to the trouble of making a 12" x 27" (30cm x 68cm) one!


Taken as products among the competition, such Sinclair devices were unimpressive. But when viewed as engineering accomplishments they do impress. Those Cambridge mathematicians squeezed scientific functions into a TI 4-function calculator chip. They did it again to a NS COPS chip with the Sinclair Cambridge Programmable (which I have collected), and again with the ZX-80 and ZX-81 computers (which I built from a kit back in the day).

See: Sinclair & the Pocket Calculator

Edited: 8 Apr 2012, 8:09 a.m.

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