On 18/07/2015 18:34, Mark Lawrence wrote:
What is an {HP calculator} roll operation?
HP calculators were proper in that they used RPN entry. i.e. 2 enter 2 + would show 4 instead of 2 + 2 =Gawd it's so long but ISTR there were 3 stack registers and the display. So you could press
1 enter 2 enter 3 enter 4and Z = 1, Y = 2, X = 3 and display = 4. Roll would rotate the entries through the display register.
ROLL and Z = 2, Y = 3, X = 4 and display = 1 and so on. There was an INV ROLL to go the other way.The 3 level stack was equivalent to nesting parentheses three times. I only had a TI-59 as it was half the price of an HP67. The TI had more memories and program steps and was faster. But it didn't say HP on the front!
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