11-30-2019, 03:42 PM

I got ahold of a cheap copy of Sinclair's 4-volume program library for the Cambridge Programmable. For those not familiar with it, the Cambridge Programmable is a tiny, underpowered programmable scientific calculator that makes the HP 25 look like a 41CX.

It has:

- 19 keys

- 36 steps of program memory

- Trig and inverse trig

- Degree/radian conversions

- Natural log and anti-log

- Square, square root, and reciprocal

- Algebraic input with a single level of parentheses

- One storage memory

- Unconditional go-to and go-if-negative

It uses a typical unmerged keystroke programming model, but interestingly, all keys default to their upper shifted functions in a program. There's a special down-shift prefix key and a numeric constant prefix key if you want to enter lower shifted functions or numbers into your program.

So the calculator isn't particularly remarkable for it's (lack of) capabilities, but rather for the quality of its documentation and program library. They really managed to cram a lot of useful material into these four books, even if a lot of it is simple formula evaluation programs (i.e. no real decision making) or functions that would be built into most other scientific calculators (e.g. powers and roots).

They actually managed to implement prime factorization on this thing somehow - see page 63 in the PDF.

https://archive.org/details/sinclair-cam...am-library

It has:

- 19 keys

- 36 steps of program memory

- Trig and inverse trig

- Degree/radian conversions

- Natural log and anti-log

- Square, square root, and reciprocal

- Algebraic input with a single level of parentheses

- One storage memory

- Unconditional go-to and go-if-negative

It uses a typical unmerged keystroke programming model, but interestingly, all keys default to their upper shifted functions in a program. There's a special down-shift prefix key and a numeric constant prefix key if you want to enter lower shifted functions or numbers into your program.

So the calculator isn't particularly remarkable for it's (lack of) capabilities, but rather for the quality of its documentation and program library. They really managed to cram a lot of useful material into these four books, even if a lot of it is simple formula evaluation programs (i.e. no real decision making) or functions that would be built into most other scientific calculators (e.g. powers and roots).

They actually managed to implement prime factorization on this thing somehow - see page 63 in the PDF.

https://archive.org/details/sinclair-cam...am-library