Message output capability of HP35s?



I am looking at buying an HP35s to use for medical dose calculations. For this I need it to be able to output a 'message' as a text data label at the same time as a numerical output.

For instance:

'Dose per hour (mg) = 35' ....etc...

I will also need to do some pretty serious branching in respose to user choices (input as numbers; again displayed against various options) for instance:

'Choose MCG (1), MG (3) or ML (4) ?'

I know that the 50g can do this but it is quite bulky (we are not allowed white coats to keep out stuff in here in the UK).

Can the HP35s do this?

Thanks in advance.




The parsing of numerical values into a string will be the impossible part. But you should be able to do branching and messages.

'Dose per hour (mg) = 35'

would have to be something like:

Dose per hour (mg)= (press R/S)
But really, why not use something like the Iphone, or perhaps a 48G or 50G emulation on a handheld device?

If you wrote an Iphone app, you might get a big market for it. And it is small, and sexy, and all of that. And physicians love Macs and Iphones, so they already have one!

Edited: 12 Apr 2010, 11:02 a.m.



An interesting suggestion; I have an android (mainly for its full large pdf display apps; iphone couldnt do that at the time) with an HP48 emulator on it. But button pushing is tricky as it is sooo small.

How hard is it to write an native app for these smartphones? I had not really considered it. Is it much more fiddly than writing calc prog; it would seem so at first thought?

Any guidance?




I don't know anything about the mechanics of writing apps for Iphone. But I do know that they are proliferating like wild-fire!

Thomas Okken, who posts here, wrote the veritable free42 for the Iphone...


I find writing native code for the iPhone to be pretty painful, I guess mainly because the APIs are so different from the Windows and Unix ones I'm used to. People familiar with Mac OS X have much less of a learning curve to deal with.

Writing native GUI apps is a lot of work on any platform I know, but it sounds like what John wants to do could also be done using HTML and JavaScript, and *that* wouldn't be much more involved than writing a calculator program.


Now that is an interesting idea! (Java Script or HTML on Iphone)

Thanks for weighing in.


Hi Again,

Actually the HP35s example that you use is actually quite acceptable; especially if the message and the input are on-screen at the same time, albeit on different lines of the display?

Hmm now thinking about a smartphone app though.




My physical 35S is lost at my son's school, so I cannot check the ability to keep the prompt in the Y register while the answer is in X. It should be possible, as long as you handle the stack appropriately. It might require "echo" of the prompt and recalling the answer to the stack from a register, rather than simply dumping the results of a calculation to the X register. All calculations use stack manipulation (except equations) and so that is that.

Also, read chapter 14 of the manual. You'll want to see how deep you have to nest. 20 is the limit for subroutines.

Edited: 12 Apr 2010, 1:56 p.m.


The 35s is very limited in terms of what you can do with message output. You won't be able to generate a message that includes calculated data - static text only - and you can only display a single message at a time, so no two-line tricks. Plus there are many documented bugs in this model that can lead to incorrect figures or memory loss under certain circumstances. Not sure I would personally trust it with anything as mission-critical as dosage calculations!

The 42s, however, features quite capable string manipulation, but is rather costly. The alternative is to get an iPhone/iPod Touch, and buy 42s for it (about $10 US, I believe). It's got nice big buttons, runs many times faster than the real thing, and gives you about 90MB instead of 7KB.

Or you could go really old-school and get a cheap secondhand Psion Organiser II. :)


Ah Ok.

The reason for going for a simple robust machine (like a 35s) is for that feeling of simplicity and reliability.

Most of the calcs that I am thinking about you sort of do in your head automatically but at times you might just need a reliable little electronic friend to tell you that you are right.

However if it is buggy then it defeats the object. Such a shame as I have a tendency for old-school things (like the idea of the robust feel of the 35s) and liked the idea of starting with a machine that feels solid but is actually in current production!

I have written a portion of the code for the old casio FX-7000GB (!) and it works well but it is already an old machine(and a bit big for the shirt pocket). I really don't like the plastic model-kit feel of current casios....

I have had a look at android app programming and it all looks a bit fancy. Not sure that I have the time to spend with all of the frilly stuff. I guess the iphone is somewhat similar.

Maybe a 42 emul is the way to go...?

I now wish I had an iphone.. hmm

I cannot thank you enough for the heads up regarding the HP35s bugs.




BTW the apps such as free42 run on hte Ipod Touch as well as on the Iphone.


BTW the apps such as free42 run on hte Ipod Touch as well as on the Iphone.

Yup, that's how I run 'em. I used 42s to find the best price per pound for cat litter earlier today. I'm posting from my iPod right now, in fact! They'll probably run fine on the iPad too, if you want a gargantuan 42s.

Another thought: How complex are the formulae you're working with? The 17bii can be had relatively inexpensively, if its (admittedly fairly sophisticated) algebraic solver can cut it.


I searched for "medical" at and hundreds of programs came up..

Or, if you'd like to do the programming yourself and you don't care about a gui, have a look at "android scripting environment". Write programs on your machine or android device. Supports scripting languages such as Lua, Perl, Python, JRuby, etc..


I have written a portion of the code for the old casio FX-7000GB (!) and it works well but it is already an old machine(and a bit big for the shirt pocket). I really don't like the plastic model-kit feel of current casios....

You shouldn't overlook the Casio FX-9860G Slim: programmable, with a C/C++ SDK available if Casio Basic is too basic, foldable (so it should fit in your pocket), and (in my opinion) well-made and not at all plasticky. At least, I like it!



Or you could go really old-school and get a cheap secondhand Psion Organiser II. :)

Several years ago I wrote this program for Psion Organizer II for the blood testing laboratory in my wife's pediatric office. The program supports counting types of leucocytes if you want to count them by type directly under microscope manually.

We simply had the Psion Organizer II available, with practically no use for it when I wrote this program.

Now, if there is a doubt wrt results of "differential white cell count" (I am not sure about the correct medical expression, but you will certainly understand) obtained by the "blood counting machine", you can check WBC differential count manually by Psion. When the operator recognizes the leucocyte in a certain field she presses the appropriate button for this type. Psion beeps when you reach 100, but you can continue counting if you want.

Just to shed some light to an easy implementation of this obsolete but robust gadget. There is nothing smart in this program, but its use is practical.

List of program							

statements: PROG:EDIT A:DKS

SG%=0 :LY%=0 :MO%=0 :EO%=0 :BA%=0 :NS%=0 :AT%=0
IF K%=65 :SG%=SG%+1 :TOT%=TOT%+1 :ENDIF
IF K%=66 :LY%=LY%+1 :TOT%=TOT%+1 :ENDIF
IF K%=67 :MO%=MO%+1 :TOT%=TOT%+1 :ENDIF
IF K%=68 :EO%=EO%+1 :TOT%=TOT%+1 :ENDIF
IF K%=69 :BA%=BA%+1 :TOT%=TOT%+1 :ENDIF
IF K%=70 :NS%=NS%+1 :TOT%=TOT%+1 :ENDIF
IF K%=71 :AT%=AT%+1 :TOT%=TOT%+1 :ENDIF
IF TOT%=100 :BEEP 800,1500 :ENDIF
PRINT "Tot.cells=";TOT%

Variables integer real
eosinophiles EO% EOSI
basophiles BA% BASO
nonsegmented NS% NSEG
segmented SG% SEGM
lymphocytes LY% LYMP
monocytes MO% MONO
atypical AT% ATYP
total number TOT% TOT

Edited: 13 Apr 2010, 3:01 a.m.


The Epocrates suite has built-in dose calculators.



Thanks Guys..

It is a shame that I recently gave all my Psion stuff to my brother...Doh!

Have had a look at the Epocrates thing; looks interesting.

Not had look at the calcs section yet.

In many ways I wanted to do something myslef so I can have 100% confidence in it (and my understanding of it actually).

A scripting language may be the way to go. Should not be too tricky either. In that way it should be nicely cross platform...

Cheers again.

(and saves me 60USD on the price of a 35s!)


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