The Museum of HP Calculators

HP Forum Archive 13

 SpeedMessage #1 Posted by bill platt on 1 July 2003, 1:33 p.m. Hi all voyager and pioneer fans, Just got my copy of a 15c. Just to start the fires, I thought I would make a post about speed. 1.st: My 15c is about 10-15% slower than my 11-C. There is variation from machine to machine (old posts talk about this). Now, given a simple loop: (pioneer syntax) LBL A -1 + x>0? GTO A 1.E40 RTN start by putting a number in the stack, say 50, and when done cycling, display wil say "1 E 40" Difference in speed: 15c: 50 loops = 24.0 sec 32sii 200 loops = 5.0 sec or about 19:1 (incidentally I used my 48gx as a stopwatch :-} ) So, what is the difference in time between rele4ase of these products? 1981 for voyager, 1988 for pioneer, so 7 years. Extrapolating linearly, that would mean that today, we should be able to build a caclulator with a speed of 63 times that of the Voyager. I bet it is even faster (but we have to be fair on caoparing at a similar price point).

 Re: SpeedMessage #2 Posted by Patrick on 1 July 2003, 2:10 p.m.,in response to message #1 by bill platt The famous Moore's law says that speed (and memory capacity) approximately doubles every 18 months, meaning there is exponential growth. Those of you with a calculator handy (!) can compute an equivalent of about a 58 3/4% growth rate, compounded continuously. Using this rate, one would expect an approximate 25 fold speedup in speed in 7 years, very much in line with the factor of 19 in your experiment. Extrapolating from 1981 to 2003, we might expect a speedup factor of 26,000! (No, that isn't factorial) This is where reality sets in and we have to look at whether we are comparing apples to apples. The Voyager series was specifically designed for long battery life. The technology at the time might have supported making a faster processor at about the same cost, but the HP engineers might have sacrificed speed for extra battery life. A famous scientist once said "Prediction is very difficult, especially when it is about the future."

 Re: SpeedMessage #3 Posted by bill platt on 1 July 2003, 5:01 p.m.,in response to message #2 by Patrick Patrick, Thanks for your reply, so, at the moore's law worked backwards, starting from a 500 MHz Palmtop, I work backwards to find a 19.2 kHz speed for the old 15C. Question is, "what was the processor speed of the old 15C?" regards, Bill

 Re: SpeedMessage #4 Posted by David Ramsey on 2 July 2003, 1:06 a.m.,in response to message #2 by Patrick Actually, Moore's law says the number of transistors on a chip doubles every 18 months. But it's been extended before...

 Re: SpeedMessage #5 Posted by Trent Moseley on 1 July 2003, 3:11 p.m.,in response to message #1 by bill platt Same results for a 1988 16C and a 1999 32SII. For the record a 1980 67 did 50 loops in 20.5 seconds. tm

 The Old Time Speedy: HP-25CMessage #6 Posted by Trent Moseley on 2 July 2003, 12:53 a.m.,in response to message #5 by Trent Moseley Fifty loops in 14 seconds! 1978 vintage. No LBL A of course. tm

 Re: Misleading !Message #8 Posted by R Lion (Espaņa) on 2 July 2003, 11:55 a.m.,in response to message #7 by Valentin Albillo Quote:or use GTO (i) for rapid reverse branching What is GTO (i)?Thanks in advance Raul

 Rapid Reverse BranchingMessage #9 Posted by Valentin Albillo on 2 July 2003, 1:54 p.m.,in response to message #8 by R Lion (Espaņa) Hi, Raul: Actually, GTO (i) is the correct form for such machines as the HP-67, HP-34C, HP-11C, etc. For the HP-15C, the correct form is GTO I, with a capital "I" instead of "(i)". GTO I, when register I does contain a negative integer (say -15), branches execution to that program step number (step 15 in this case), instead of searching for a label. As no label search is performed whatsoever, it executes much faster, and besides it doesn't require a label at all at the destination step. It's a rarely seen technique, but available and powerful nevertheless. Best regards.

 Re: Rapid Reverse BranchingMessage #10 Posted by gene on 2 July 2003, 5:00 p.m.,in response to message #9 by Valentin Albillo My guess about why this is a rarely seen technique (GTO I in particular) is because of the overhead required to store the step number into I, particularly when one wanted to change the destination in a program. And, of course, the difficulty of debugging and maintaining a program using absolute addressing. Yuck! I know it RUNS faster, but the pain involved in getting there is nasty. :-)

 Speed is MisleadingMessage #11 Posted by bill platt on 7 July 2003, 10:30 a.m.,in response to message #7 by Valentin Albillo Valentin, Thanks for your excellent response--it is just the sort of dialog I hoped to start! Just now back from a short vacation---so looking forward to your next 15c quiz. Regards, Bill

 Re: Speed -- a few more data points . . .Message #12 Posted by Paul Brogger on 2 July 2003, 11:21 a.m.,in response to message #1 by bill platt HP-97 -- 50 loops in 21.5 seconds HP-34c -- 50 loops in 21.9 seconds HP-32s -- 200 loops in 4.0 seconds HP-28C -- didn't care to figure out RPL (again) HP-48G -- too lazy to figure out RPL (I used my watch as a stopwatch . . . ) Lesson: RPL -- Use it or Lose it!

 Re: Speed -- a few more data points . . .Message #13 Posted by bill platt on 7 July 2003, 11:46 a.m.,in response to message #12 by Paul Brogger Paul, looks good. Notice the correlation between your 97 and Trent's 67---this should be, as they are the same in their guts, yes? Take a look at Valentin's post---he has great points about the validity of speed tests. I am going to play with some other loop structures and see what happens. Regarding RPL---I am a newbie to RPL---but yes it seems a bit like "use ot or lose it." But I did successfully figure out how to do an IF-THEN-ELSE recently on RPN, so maybe I will be able to make a REPEAT-WHILE...... regards, Bill

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