On 2015-07-18 19:28, William Ray Wing wrote:
On Jul 18, 2015, at 1:34 PM, Mark Lawrence <breamore...@yahoo.co.uk> wrote:
[byte]
What is an {HP calculator} roll operation?
The original Hewlett Packard “Scientific” calculators (HP-35, 45, 65, etc) that
used Polish notation (operand, operand, operation; with no “=“ sign) had a
stack.
FYI, Polish Notation is a prefix notation; the operation comes first.
What you're talking about is Reverse Polish Notation, where the
operation comes last.
> That stack itself could be manipulated (e.g., interchange X and Y).
One of the stack manipulation commands was “Roll” which moved the top
entry into X and pushed remaining elements up one. Later versions had
both Roll-up and Roll-down, Roll-down moved the X entry to the top of
the stack and dropped the other elements.
Bill (Who still uses an HP-45 emulator on his iPhone)
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