Surprising finds in TI's long-form programmable calculator manual

I have a fondness for the TI-57 programmable - it was very expensive for me, as a schoolchild with a paper round, but at £35 actually quite cheap. Mine came with a 60 or 70 page manual, with a single mysterious reference to the SOAP bar inside.

It turns out that TI also, or originally, provided a much much more extensive manual, which has an entire section on the history of calculators (or computers) and a detailed explanation of how the TI-57 works. It’s a single-chip calculator, and apparently SOAP stands for Serially Oriented Arithmetic Processor.

Here’s the full manual - it’s got lots more programming examples than mine too:

Here are a few snaps of mine, the short version:

I also have snaps of my calculator, partially disassembled, just prior to me taking the chip out for reverse-engineering:

via hpmuseum