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HP 35S - long live the RPN! - Printable Version

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HP 35S - long live the RPN! - Dirk E. - 11-21-2014 12:20 AM

Two days ago I found an emulator not asking for any key, registration or payment on an HP support site, yesterday this page was gone; only a few Q&A left explaining things findable in the manual (or on MoHPC) with slightly more effort. Just three days ago I had received my 'spare' 35s (you never know), that obviously someone had returned to the store (it has the known bugs, otherwise it's ok, no different rev.). My hope is still to become a happy WP 31s and WP 34s owner, maybe even a WP 43s?

Like others here I find myself using the 35s more and more despite it's size and shortcomings of which most annoying to me is that some RPN function positions moved against the 15C e.g. (RCL STO Rdn x<>y no more around ENTER, but a "()" primary function key that does nothing in RPN etc.). Many functions require 3 keystrokes to be reached, that's similiar to "the other" non-graphing programmable scientific calculator fx-5800P. But I doubt that I'll afford to 'teach' the Casio RPN; it's possible, but you can save the programs only on paper or textfile via PC keyboard. Another point is that the hinge for the front cover will likely break soon (as it did on my first unit), so it's not to take-everywhere.

At this place I'd like to vote for more RPN use - many posts refer to 35s EQN or ALG use, but - the bugs aside - in programs they're much slower, and if you take the time to note down at least the important things for a program, there's far less trouble later and an RPN keystroke program doesn't have to look more complicated. To me these endless round bracket chains are more confusing.
Tony Thimet published his version of a performance test with an explicit program listing for HP 35S. The test considered 34 "substantial operations"; if it finishes in less than 5 s, an outer loop should give the measuring more accuracy. Thus the "performance index" calculates

((outer loops) x 34) / time (s).

(It's not exactly operations per second, but it allows for comparison.) Here's my test on HP 35S in RPN and in ALG modes. I broke the single line expressions to show better how the code compares:
HP 35s

RPN                           ALG
37.05 s  perf.idx 9.2         51.05 s  perf.idx 6.7

B001 LBL B                    A001 LBL A
B002 10       STO A           A002 10 >A
B004 10       STO B           A003 10 >B
B006 1        +               A004 (B + 1
B008 4.567E-4 -                       - 4.567E-4
B010 70       +                       + 70
B012 69       -                       - 69)
B014 7        x                       x 7
B016 11       /                       / 11
B018 RCL B                    A005 B
B019 1        -                      - 1
B021 STO B                           >B
B022 x!=0?    GTO B006        A006 x!=0?     GTO A004
B024 Rv                       A008 SQRT(
B025 LOG                                SQRT(
B026 SIN                                SIN(
B027 vX                                 LOG(
B028 vX                                     REGy))))
B029 RCL A                    A009 A
B030 1        -                      - 1
B032 STO A                           >A
B033 x!=0?    GTO B004        A010 x!=0?     GTO A003
B035 RTN                      A012 RTN
In ALG mode it's almost as slow as the fx-4500PA (slightly slower successor to the fx-4500P from 1989) which I personally like for it's compactness and it's approach to save keystrokes (no mandatory brackets with single-operand functions and avoiding some multiplication signs e.g.)

55.09 s  perf.idx 6.1

LINE1   A=10 :
        LBL 0 : B=10 :
        LBL 1 : X=(B+1
                    /11 :
                    -1 :
            B>0 => Goto 1 [fi]
            X=v _
                        X :
               -1 :
         A>0 => Goto 0 [fi]
(This is all on one line, broken just for comparison to the above. The "v" stands for square root. The "[fi]" - end-if - is a special character, outlined triangle towards right, delimiting expressions as ":" or CRLF would.)

The competition is more than 3 times faster, it has also commands for structured programming, but these are on the third page of the Program-Function menu (6 keystrokes):

10.09 s (10x) perf.idx 33.7               8.42 s (10x) perf.idx 40.4
30.04 s (30x) perf.idx 34.0               24.72 s (30x) perf.idx 41.3

Prog PERFM                               Prog PERFS
 30 ->A :                                 For 30 ->A To 1 Step -1 :
 LBL 0 : 10 ->B :                         For 10 ->B To 1 Step -1 :
 LBL 1 : (B+1                               (B+1
           -4.567E-4                          -4.567E-4
           +70                                +70
           -69)                               -69)
           x7                                 x7
           /11 ->X :                          /11 ->X :
          B                               Next:
              ->B :
     B>0 => Goto 1 :
          v _(                             v _(
           v  (                             v  (
            sin (                            sin (
             log (                            log (
                  X)))) ->X :                      X)))) ->X :
     A                                    Next:
         ->A :
  A>0 => Goto 0 :
  X                                       X
(Also the "v" means square root here, and I entered the programs as "1 line" using ":" as expression/command separator only.) Maybe it's not fair to use the advanced loop commands in such a comparison? Should I do another test with DSE (which the 4500P lacks) on the 35s?

- So far about the ALG mode - I'd say: Use RPN :-)

Then there are the limited trigonometric function calculations near n x pi/4. The forum archive has a beautiful demonstration listing in message 27 from KS in the thread "The trigonometric bug is spreading !?".

Somewhere in this or a related thread I read that other calculators give even shorter responses in this range - these are from my collection:

sin 3.1415926 (rad)

free42 (1.5.5 dec) 5.35897932384626...e-8
TI-66: 5.358979323846E-08
fx-4500PA: 5.36E-08
HP 15C LE: 5.359E-08
fx-5800P: 5.35898E-8
HP 35S: 5.358979E-8

If I'd need for sure higher accuracy in this field (but I'm not aware of any such need for myself), I could type in and use Takayuki Hosoda's alternate trig. functions or look for other workarounds like e.g. sine for angles from 1e-2 to 1e-4 deg (below 1e-4 deg the ->RAD does it):


result: 1.74532925199E-6

- It contines endlessly: I like the nicely readable display except for some too small annunciators and the exponent out of sight in "all" mode, I like the programming except for missing indirect branches and just single-letter labels, I love the RPN use except for some keys moved around, I like the good readable key labels except for there's no distinction between menus and just functions ... where was binary burried?

Two years after I bought it and more than seven years now after HP released the 35s I have little hope that the industry will issue any new nice and pocketable *RPN* calculator or even fix the boldest issues with this one. Comparing the 300s+ with other manufactuerers' I see almost no difference left. Let's make the best out of what we have and support the efforts around the WP family. (Am I nostalgic?)

Long live RPN!
Cheers, Dirk
Sanyo CZ1210, TI-66, fx-4500P, HP 15C LE, fx-5800P, HP 35s ...?

RE: HP 35S - long live the RPN! - jebem - 11-23-2014 11:50 AM

Despite so many detractors, I find the HP-35S to be an excellent, versatile, well built, compact and powerful calculator.

Among the current HP production, besides this HP-35S what do we have?
The HP-12C, the HP-50G and the HP-Prime.
The 12C is a landmark in longevity but oriented to the financial market.
The 50G is a blast from the past, powerful and big to carry around.
And then we have the Prime, a beautiful piece of modern up to date technology, full blown math machine environment that runs as fast as it is possible on a somewhat compact pocket computer.

IMHO, for daily usage to carry around, the HP-35S fits the bill nicely, better than the other HP offerings.
My advice for those that still don't have the HP-35S in the collection: get one or two now, before it will be too late to acquire them for peanuts.

As for the WP-34S, it is an excellent and unique RPN implementation, sporting a set of impressive math features.
If one is on the diy route, get a couple of HP-30B while the prices are low, order the keyboard overlays and the Xtal/caps set, build one serial/USB cable and flash it with the WP-34S firmware.
Or just order it ready made from Eric.

35 years between these two HP models of my collection: the original 35 and the 35S.

[Image: HP-35_HP-35S_001.jpg]

RE: HP 35S - long live the RPN! - jebem - 12-02-2014 05:55 AM

Talking about low cost new HP-35S calculators:
I just remember one seller referred elsewhere in the MoHPC some time ago, concerning low cost HP-15C LE machines.

They still have the HP-35S selling for an excellent price with free shipping, among other HP machines.

RE: HP 35S - long live the RPN! - Paul Dale - 12-02-2014 06:33 AM

If only the 35S used flash not masked rom. It would have been the ideal repurposing platform. Way more RAM than the 30b, just as much ROM and a more efficient instruction set.

- Pauli

RE: HP 35S - long live the RPN! - brouhaha - 12-02-2014 07:36 AM

(12-02-2014 06:33 AM)Paul Dale Wrote:  If only the 35S used flash not masked rom. It would have been the ideal repurposing platform. Way more RAM than the 30b, just as much ROM and a more efficient instruction set.

The 35S has a much less efficient instruction set, actually. It uses a 6502-compatible core, which is atrocious for running C code.

RE: HP 35S - long live the RPN! - Paul Dale - 12-02-2014 08:08 AM

(12-02-2014 07:36 AM)brouhaha Wrote:  The 35S has a much less efficient instruction set, actually. It uses a 6502-compatible core, which is atrocious for running C code.

Properly coded, it is very compact. It would just require not coding too much in C or other high level compiled language Smile

Still, the point is moot, the device is ROM only.

- Pauli

RE: HP 35S - long live the RPN! - Les Bell - 12-02-2014 08:14 AM

(12-02-2014 07:36 AM)brouhaha Wrote:  The 35S has a much less efficient instruction set, actually. It uses a 6502-compatible core, which is atrocious for running C code.

P.J. Plauger, who (I believe) wrote the Whitesmiths C compiler, famously remarked that his company was unable to provide a compiler for the 6502 because it was "below C level".