Need assistance

[mm0fmf]

On 18/07/2015 20:10, Joel Goldstick wrote:
> On Sat, Jul 18, 2015 at 2:51 PM, mm0fmf via Python-list
> <python-list at python.org> wrote:
>> 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
>> 4
>>
>> and 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!
>>
> I have an hp35.  But to be 'really' cool you have to have an hp35 that
> just says hp.  Those were the very first ones
>
I want a real HP16C and have been tempted to buy one from eBay.