Differences between the HP 15c CE and the original HP-15C

[Valentin Albillo]

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Hi, Gene, {my highlighting}

(06-13-2023 12:29 AM)Gene Wrote:  The CPU is roughly 200x faster, but the final speed increase depends upon the mix of operations being executed (of course).

Of course. That much is obvious.

Quote:Rather than promising all instructions will run at X times faster, the safer thing in the manual was to under promise.

First, no one should promise anything, the manual should just give true and useful factual information, not promises, under or overstated. A much proper statement would be, e.g.:

"The actual speed increase varies with the particular instruction or mix of instructions executed but typically will be ~10-20x for instructions executed from the keyboard, and ~170-180x for running programs."

Quote:Some operations are not much faster on the HP-15C CE than on the HP-15C LE, but some are faster.

Which ones ? Can you give some examples ? How much faster ?

Quote:For example, the N-queens problem found here on the museum site [...] 186 X faster than the original. The LBL A + GTO A loop run for 60 seconds [...] 183X faster. [...] your HP-15C Multiprecision e program [...] 178x faster,

Those three programs surely have very varied mixes of instructions. Mine, for instance, has a 42-instruction loop which includes matrix operations, tests, storage, arithmetic, branching, incrementing, the works, which is executed 124 times, thus more than 5.200 user instructions executed in all.

This surely allows a pretty good average on instructions' execution speeds, which comes out as 178x for my program, and similar values for your own two examples, and I feel it should be included as part of the 10-20x statement in your OP (and in the list you've based your OP on, and in the manual if it doesn't mention it. Not including it has the potential to unfairly belittle the HP-15C CE's speed capabilities.

A "promise" safety factor of 2.0 might be acceptable, but a safety factor of 8.0-9.0 is way too much.

Thanks and best regards.
V.

P.S.: My other possibly useful HP-15C programs for speed benchmarking purposes include:

Feigenbaum for the HP-15C (Message #4), 477 seconds for 7 iterations.
HP-15C Mini-challenge: My Original Solutions & Comments (Message #55), 444 GSB A takes ~7 min.
A physical HP-15C solution in 48 minutes (Message #13), ditto, it takes 48 min. to find the solution.