16 Sep
2011
16 Sep
'11
4:58 p.m.
Tony Duell wrote:
My (considered?) opinion is that it's certainly a
postfix machine in
that
you enter both numbers into Y and X before doing an
arithmetic
operation.
But becuase of the lack of automatic stack operation,
it's not an RPN
machine?
Isn't use of postfix operations the defining characteristic of Reverse
Polish Notation, since Polish Notation used prefix operations?
While the conventional use of postfix operations is based on a stack, it
isn't clear that this is a requirement.
To implement fully general postfix notation would require an infinitely
deep stack, while calculators prior to the HP-28C only had a small fixed
number of stack levels. This didn't stop them from being considered
postfix or RPN.
Eric