Need assistance
William Ray Wing
wrw at mac.com
Sat Jul 18 14:28:05 EDT 2015
> On Jul 18, 2015, at 1:34 PM, Mark Lawrence <breamoreboy at 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. 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)
> --
> My fellow Pythonistas, ask not what our language can do for you, ask
> what you can do for our language.
>
> Mark Lawrence
>
> --
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