this was my first programmable calculator (this is actually
it!) from 1977. sinclair burst onto the calculator scene in the early 70's
offering cost effective alternatives to the models of hewlett packard and
texas instruments. this was their first programmable.
it was amazing for its time, a 36 step programmable memory (volatile)
in which many tricks could be used to save space. since each key press
cost a step, they represented their shifted function in program mode (ie
the function written above). to program numbers you must precede input
with the # character (which costs a step). another trick is that the
program will run round from step 35 to step 00, often saving a jump.
it has one conditional branch, goto if neg, from which any test
may be determined by careful program re-arrangement.
it came with a program library consisting of 4 books. each covering
- general/finance & stats
- physics & engineering
the library programs were well written and managed to extract a great
deal of functionality out of the, otherwise limited, machine. later,
sinclair superseded this model with the enterprise.
but, by then more sophisticated programmables were available at reasonable
i discovered experimentally, that pressing divide would
interrupt program execution and display the current value, thereafter run
could continue execution (as far as i know this is not documented). this
new feature enabled me to write a whole new range of interesting programs;
dice throwing, random numbers, a stopwatch timer and games like whack a