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20b - Observations - Printable Version

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20b - Observations - Thomas Radtke - 07-15-2009

It appears, the 20b acts partially like a RPL calculator: 1 ENTER 2 ENTER + results in 3 instead of 4. OTOH, a percentage operation a b % leaves a on the stack, as opposed to RPL calculators like the 48 series. Quite confusing, but I like it.

An interesting bug: Some error conditions apparently leave an invalid number on the stack. Try e.g.:

CE
TVM reset
N I/YR PV (ignore errors)

Now cycle through the stack, some entries are missing. These are maybe invalid numbers.


Re: 20b - Observations - Gene Wright - 07-15-2009

Hi Thomas!

1) Yes, the 20b uses a "command line" approach as an input to the stack. Your addition example points out the effect quite well. Another result can be that if you have a stack full of 4 values and begin typing another number, if you press ON/CE, you still have all 4 values. On a "true RPN" machine, you would have lost the value in T. On the 20b, T is lost only if you do something with the value you are keying it. ON/CE is an "abort" button.

2) The % operation works as "RPN" does.

So, a bit of a hybrid, probably because it reuses the RPL approach to inputs on the stack.

3) If you're referring to an apparently blank display, then yes, this is a non-normalized number aka error result. I know HP is aware of this. Of course, a blank display should never be returned to the user, so this is a bug.

What ROM revision is on your 20b?


Re: 20b - Observations - Thomas Radtke - 07-15-2009

Hi Gene,

Quote:
What ROM revision is on your 20b?

How to find it out?


Re: 20b - Observations - Tim Wessman - 07-15-2009

On-PMT opens the hidden menu. Scroll up and down and you will see it in there.

Also, can you give the example that returns the blank screen so I can check it is fixed? Thanks.

TW


Re: 20b - Observations - Thomas Radtke - 07-15-2009

Quote:
On-PMT opens the hidden menu. Scroll up and down and you will see it in there.
SW Version shows 8 01 2008

Quote:
Also, can you give the example that returns the blank screen so I can check it is fixed? Thanks.
As a more simple approach to get one blank entry, press

CE
N
I/YR
Arrow down (4 times)



Re: 20b - Observations - Walter B - 07-15-2009

FWIW, SW Version 6 17 2008 shows the same bug.


Re: 20b - Observations - Gene Wright - 07-15-2009

Of course, since that is an earlier firmware, it means it had not been fixed by August of last year. :-)

Hopefully, unlike some software companies, updated HP firmware does not break things that used to work!


Re: 20b - Observations - Walter B - 07-15-2009

Quote:
Hopefully, unlike some software companies, updated HP firmware does not break things that used to work!

Hopefully, but not for sure ;)

Quote:
Of course, since that is an earlier firmware, it means it had not been fixed by August of last year. :-)

Oh, that was M DD YYYY :( Sorry I didn't recognize that.


Re: 20b - Observations - Gene Wright - 07-15-2009

Oops. Tough to know when the digits don't indicate where the day is located, isn't it?


Re: 20b - Observations - cyrille de Brébisson - 07-16-2009

hello,

it's not an 'invalid number', which would be a serious bug, it's a perfectly normalized NaN number...

the problem is that the UI does not realy know how to handle NaNs...

I am trying to remove all occurrences of such problems.

regards, cyrille


Re: 20b - Observations - Thomas Radtke - 07-16-2009

Great, allthough this bug doesn't seem to affect normal operation. May I be so cheeky to ask whether someone is debugging the 35s? :^)


Re: 20b - Observations - Marcus von Cube, Germany - 07-17-2009

I guess, the 20b software is a one man show and we are lucky he is here on the forum. :)


Re: 20b - Observations - bill platt - 07-17-2009

Yes, that is true.

And of course never overestimate how man people are behind the curtain! (It is always amazing to realize how much one motivated and talented person can do).

I lurk most of the time on these issues but find it interesting to follow them.