Need assistance

[William Ray Wing]

> 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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