HP 39gII considered annoying, part 1

[Pete Wilson]

My first thought after (finally) getting a 39gII was that it was really worrying as a basis for the HP Prime, a new flagship for HP.

I intended to post some issues I had, but I had opportunity to run a quick calculation and compared my (emulated) 48gx (though my 50g would have been similar) to the 39gII. While involving a unit calculation is probably extremely unfair (I can't imagine improving the 50g model much), it does hilight other issues I have along the way. I would welcome any suggestions on improving the use/flow of the 39gII as well.

So the (lunch) problem was to figure out if the first atomic bomb, apparently based around 100 lbs of uranium, was terribly inefficient given the quoted fact that no six inch pure uranium nuggets are floating around in space, since that size would go critical (as opposed to the potential for other pure nuggets). (These figures aren't exact, but that was the remembered facts.)

A quick check of The Elements says the density of Uranium is 19.05 g/cm^3. A quick Google says the volume of a sphere is 4/3*pi*r^3.

On the 48gx:

100 rShift Units Mass LB

19.05 g rShift Units VOL rShift cm^3

/ lShift Units UBASE

gives 2.381E-3_m^3 as the volume of 100 lbs of Uranium. Switching modes to fix 6:

rShift MODES CHOOSE dwn OK right 6 OK OK

yields 0.002381_m^3. Compute the diameter with:

3 * 4 / lShift pi / lShift >Num 3 rShift x_root_y 2 *

so 0.165675_m in diameter

rShift UNITS LENG lShift IN

or 6.522644_in in diameter. So not too wasteful.

Contrast with doing this on a 39gII:
Turn it on and wait the two seconds to boot up.

100 Math Units dwn*7 right dwn*3 OK / 19.05 Math right dwn OK

* 1 Math up*3 right dwn OK ENTER

(Couldn't figure out best way to enter 19.05_g/cm^3.)

Giving us 5.249_(lb*g^-1*cm^3) which we base with:

Math up*4 right dwn*4 OK shift ANS ENTER

which gives us 2.381E-3_m^3 then we change modes to Fix 6:

shift Modes dwn Choose dwn OK right 6 OK HOME

Since the display doesn't change the old answers (!) we do:

shift ANS ENTER

and see 0.00238106_m^3 (what happened to fix 6???) of uranium. Then we compute the diameter of a sphere of that volume:

2 * ( 3 shift NTHROOT ( 3 / 4 * up COPY bs*4 / shift pi ENTER

(We lost precision, but we can't take NTHROOT of a unit and I couldn't figure out a way to strip units from ANS.)

So now we have 0.165675 meters which we convert to inches

Math right dwn*2 OK up COPY Math dwn*2 right OK , 1 Math right dwn*15 OK ENTER

And we have 6.522638_inch.

I think you can see some annoyances :)

[Chris Smith]

Hmm that does look a little frustrating.

I assume the Prime is probably the same. Looks pretty but functionally retarded for the sake of education *choke* clear my throat: I mean government mandated training.

Time to start stockpiling 50g's with the ammo and canned goods?

Perhaps I'm getting cynical in my not so old age...

Edited: 21 May 2013, 7:35 a.m.

[Gilles Carpentier]

Quote:

---

I assume the Prime is probably the same

---

At least the Prime have a 'Units' key and a '_' key on its keyboard (look the pictures) , so I suppose there are no need to navigate in complex menus for work with units. And a "touch screen" allows many new possibilities in human-calc-interface. For example, I don't know if it is the case, but you can easily imagine that pushing 'units' key displays all possibilities of units on the touch screen.

so wait a see...

I also notice that the Prime has a 'non-shifted' EEX key ;) The shifted EEX on the 39Gii is annoying
And the Prime have "user keyboard" So I suppose you can use this to personalize the keyboard.

Edited: 21 May 2013, 8:16 a.m.

[Chris Smith]

Having used and written software for touch screen devices going back to the 90's, I still don't buy it. Without physical tactile feedback, its hard to do anything in a deterministic fashion when using it.

Look at the Prime interface - it has menus and icons on the same screen. Its going to be really hard to use them accurately, just like its impossible to draw on an iPad past child-like splodging despite all those terrible adverts to the contrary.

The non shifted EEX is good though. I don't know why that was shifted to start with as even the cheap no brand scientific calculators you can get in the UK "PoundLand" chain for £1 don't have shifted EEX :)

For ref the nSpire has units and _ right there, but the implementation is still horrid compared to the 50g.

[Gilles Carpentier]

Contrast with doing this on a 39gII: Turn it on and wait the two seconds to boot up.

100 Math Units dwn*7 right dwn*3 OK / 19.05 Math right dwn OK

* 1 Math up*3 right dwn OK ENTER

(Couldn't figure out best way to enter 19.05_g/cm^3.)

Giving us 5.249_(lb*g^-1*cm^3) which we base with: 

Math up*4 right dwn*4 OK shift ANS ENTER

which gives us 2.381E-3_m^3 

Less keystroke is:

Math Unit 1 2 100 Math 8 4  / 19.05 Math -> 2 <- ( -> / Math 5 2 ) ENTER

-> 2.381E-3_m^3

etc.

But I prefer the 48/50 way to do and the RPN entry and to see all intermediate results in an interactive way

Edited: 21 May 2013, 11:38 a.m.

[Pete Wilson]

Unless you memorize the shortcuts, the 8 4 and 1 2 are really incredibly poor. At the very least, they should display in front of each line, so you aren't counting lines or arrowing down to see what it was - that way you would stand a chance of using some of them. Of course, no pagedown keys. I don't think anyone could say learning Math 5 G for inch (oops! I meant 3 G) is reasonable.

[Gilles Carpentier]

I totally agree ...

I hope a huge improvment for this with Prime and perhaps with future ROM for the 39GII (?). The way HP39GII works for this is not ergonomic at all

I also noticed that you can use the first letter in the choose box... But it does not help so much