HP-17BII+ RPN Mode "variable length stack" bug or implementation
lnx...@gmail.com
have older calculators including in particular a 1983 HP 12c, a
HP-15c, HP-25c, and others. Part of the below is what I read in the
manual ,part is what I observed, and part is what I inferred.
Does anyone know where I can find more or have more information on
whether the RPN stack in fact works like the below and maybe why?
I have read on a couple of collection sites that it is a Bug ... but,
I am wondering if in fact this was intentional since it has not been
fixed ( i.e., maybe it is supposed to be like a dynamic stack in
programming)?
THE HP 17BII+ RPN Mode Stack
--------------------------------------------
In he HP 17BII+ RPN mode ... initially only the permanent x register
exists. Then as data is entered onto the stack or consumed from the
stack, the stack size varies. The size varies over a range from 1 to
4 levels deep depending upon the amounts of data entered and
consumed.
Therefore, at most, the HP 17BII+ stack is composed of one permanent X
register and three non-permanent registers labeled y,z, and t:
X receives the "calculator line", Status:permanent memory, present
always, head of the "dynamic stack"
Y accumulator, Status: non-permanent, created and destroyed as
needed
Z temporary, Status: non-permanent, created and destroyed as needed
T top, Status: non-permanent, created and destroyed as needed
Pressing [SHIFT], [CLR DATA] destroys the y, z, and t registers
resetting the calculator to its initial state of having an x register
only.
The above is unlike my HP 12c, HP-15c, HP-25c, and other HP RPN / RPL
calculators.
Thanks in advance,
{fdw}
lnx...@gmail.com
Actually, scratch my RPL comment ... it is like RPL somewhat but, the
stack can only grow to 4 levels not to all of memory. {Fdw}
Christoph Widmer
just as an ordinary old-fashioned four-level stack. I still have a
manual from a 17BII+ which broke, and this manual is full of obviously
non-sensical mistakes (German translated from English by a Chinese). I
would suspect that this is either plain wrong or at least a very quirky
way of describing the functioning of the stack.
lnx...@gmail.com schrieb:
cyrille de Brebisson
the HP17BII IS indeed as started by the first poster a RPL calculator that
EMULATES a RPN calcualtor, and does have an "inifinte" stack and "creates Y,
Z, T registers as needed in the RPL stack.....
however the HP17BII+ was completly recreated in C and is not a RPL
calculator behind and has permanetly allocated X, Y, Z and T registers.
cyrille
"Christoph Widmer" <cwi...@gmx.ch> wrote in message
news:46c419f1$1...@news.bluewin.ch...
lnxfdw
Christoph:
Thanks for looking at this. This is a curiosity only, I don't think
is changes RPN operations ... it is something I noticed right away.
If you take the time to do the below and view something different
then
let me know. Also, let me say that I ran out of time to clean all of
the
language up so if you can look past that
I neglected to say ... a little sleepy last night that I now have both
models: (1) a 1995, Singapore, HP-17BII and (2) a new HP-17BII+. I
also
admit that I have had and used the HP-12c since it was new in 1983.
The
following is how I first noticed a difference.
On the 1983 HP 12c an RPN only calculator I observed the following:
(1) [f] [REG] resets the x,y,t,z registers to zero.
(2) Rolling the stack with [R Down Arrow] after preforming (1) above
"appears" to the viewer to move through the cleared stack in
sequential order. Whether it does or not, I don't know.
(3) Performing step (1) and then performing a keystroke hitting the
number 1 puts the digits 1. in the x register. Rolling the
stack
with [R Down Arrow] 4 times appears to move me through the stack
ending with a 1.00 as expected.
(4) Performing a keystroke hitting the number 2 puts the 2. digit in
the x register and moves the digits 1.00 to the y register.
Rolling the
stack with [R Down Arrow] 4 times appears to move me through the
stack.
I see the following sequence in order: "2. 1.00 0.00 0.00 2.00."
The point is
here the viewer sees the x,y,z, and t or at least appears to
(i.e., what
else would the roll down keystroke be for?).
Now for the HP-17BII and for the HP-17BII + change steps 1 through 4
to conform
to the calculators. I would have expected before having these that
test on both
would have repeated exactly my experience with the HP-12c and others.
On the HP 17BII and the HP 17BII+ perform the following:
(1) HP 17BII: [gold shift] [Clear Data] / HP 17BII+: [gold shift] [CLR
DATA]
(2) Rolling the stack with [gold shift] [R Down Arrow] four times
after preforming
step (1) above "appears" to the viewer to move through the
cleared stack in
sequential order. Whether it does or not, we don't know.
(3) Performing step (1) and then performing a keystroke hitting the
number 1 puts the digit 1 on the calculator line. Rolling the
stack with [gold shift]
[R Down Arrow] 4 times appears to "enter" the digit 1 into the x
register
and does not appear to move me through the stack. All I see is "1
1.00 1.00
1.00 1.00" when I might expect to see "1. 0.00 0.00 0.00 1.00"
Further, when I
perform an [x<->y] exchange I view a zero from the y register but,
that "roll down"
produced a "1.00"? From that one may infer that for the HP-17BII/
HP-17BII+
implementation that "rolling through the stack" does not occur ...
all one really sees
is the data in the x register viewed over and over.
(4) Next beginning with 1.00 in the x register I perform a keystroke
placing the
number 2 puts on the calculator line. Rolling the stack
with [R Down Arrow] 4 times appears to "enter" the digit 2.00
into the x register
and moves the digit 1 to the y register. Rolling the stack
with [R Down Arrow] 4 times appears to "enter" the digits 2.00
into the x register
and moves the digits 1.00 into the y register. Rolling the stack
does not appear to
move me through a complete stack on moves me through the x and y
registers. All I
see is "2 1.00 2.00 1.00 2.00" when I expect to see "2. 1.00 0.00
0.00 2.00." So
at best here we are only rolling the "x" and "y" registers and are
not getting a
view of the "y" and "t" registers ... if they even exist!
Further, when I perform an [x<->y] exchange I view the digit "1"
from the y register.
So one might infer that for the HP-17BII/HP-17BII+ implementation
that "rolling through
a complete stack" does not occur ... all you really see is the
data in the x register
and y register viewed over and over (i.e, the first two elements
of a dynamic stack?).
So, at least on my equipment, the HP-12c and the HP-17BII/HP-17BII+
perform differently
when going through the steps above. I am not sure that "plain wrong"
or "quirky" would
apply here ... but might say that they do test "different" than say
the HP-12c. The "creation/destruction mechanism" described in the
first post was a guess only ... I would imagine only the firmware
developers know for sure. I was really curious as to whether
this was a "feature" from the new HP ... I liked the old one better
but, we make do with
what we have.
Thanks again for your time and consideration of this matter.
Frank
lnxfdw
> hello,
>
> the HP17BII IS indeed as started by the first poster a RPL calculator that
> EMULATES a RPN calcualtor, and does have an "inifinte" stack and "creates Y,
> Z, T registers as needed in the RPL stack.....
>
> however the HP17BII+ was completly recreated in C and is not a RPL
> calculator behind and has permanetly allocated X, Y, Z and T registers.
>
> cyrille
>
I see my posting is skewed. I am going to try one more time to see if
I can make a posting that is more readable. Thanks {fdw}
Christoph:
Thanks for looking at this. This is a curiousity only, I don't think
is changes RPN operations ... it is something I noticed right away.
If you take the time to do the below and view something different
then
let me know. Also, let me say that I ran out of time to clean all of
the
language up so if you can look past that
I neglected to say ... a little sleepy last night that I now have both
models: (1) a 1995, Singapore, HP-17BII and (2) a new HP-17BII+. I
also
admit that I have had and used the HP-12c since it was new in 1983.
The
following is how I first noticed a difference.
On the 1983 HP 12c an RPN only calculator I observed the following:
(1) [f] [REG] resets the x,y,t,z registers to zero.
(2) Rolling the stack with [R Down Arrow] after peforming (1) above
"appears" to the
viewer to move through the cleared stack in sequential order.
Whether it does or not,
I don't know.
(3) Performing step (1) and then performing a keystroke hitting the
number 1 puts the
digits 1. in the x register. Rolling the stack with [R Down Arrow]
4 times appears to
move me through the stack ending with a 1.00 as expected.
(4) Performing a keystroke hitting the number 2 puts the 2. digit in
the x register and
moves the digits 1.00 to the y register. Rolling the stack with [R
Down Arrow] 4 times
appears to move me through the stack. I see the folowing sequence in
order:
"2. 1.00 0.00 0.00 2.00." The point is ... here the viewer sees the
x,y,z, and t or at
least appears to (i.e., what else would the roll down keystroke be
for?).
Now for the HP-17BII and for the HP-17BII + change steps 1 through 4
to conform
to the calculators. I would have expected before having these that
test on both
would have repeated exactly my experience with the HP-12c and others.
On the HP 17BII and the HP 17BII+ perform the following:
(1) HP 17BII: [gold shift] [Clear Data] / HP 17BII+: [gold shift] [CLR
DATA]
(2) Rolling the stack with [gold shift] [R Down Arrow] four times
after
peforming step (1) above "appears" to the viewer to move through the
cleared stack
in sequential order. Whether it does or not, we don't know.
(3) Performing step (1) and then performing a keystroke hitting the
number 1 puts
the digit 1 on the calculator line. Rolling the stack with[gold
shift] [R Down Arrow]
4 times appears to "enter" the digit 1 into the x register and does
not appear to move
me through the stack. All I see is "1 1.00 1.001.00 1.00" when I
might expect to see
"1. 0.00 0.00 0.00 1.00" Further,when I perform an [x<->y] exchange I
view a zero from
the y register but, that"roll down" produced a "1.00"? From that one
may infer that for
the HP-17BII/HP-17BII+ implementation that "rolling through a
permanent stack" does not
occur ... all one really sees is the data in the x register at the
head of the stack
viewed over and over.
(4) Next beginning with 1.00 in the x register I perform a keystroke
placing the number 2
puts 2. on the calculator line. Rolling the stack with [R Down
only on my part... I would imagine only the firmware developers know
for sure. I was
really curious as to whether this was a "feature" from the new HP ...
I liked the old one
better but, ... we make do with what we have.
lnxfdw
>
> the HP17BII IS indeed as started by the first poster a RPL calculator that
> EMULATES a RPN calcualtor, and does have an "inifinte" stack and "creates Y,
> Z, T registers as needed in the RPL stack.....
>
> however the HP17BII+ was completly recreated in C and is not a RPL
> calculator behind and has permanetly allocated X, Y, Z and T registers.
>
> cyrille
>
Hi Cyrille:
I did not read your message completely before. I canceled my earlier
response.
When you said: (1) "the HP17BII IS indeed as started by the first
poster a RPL calculator " and (2) "however the HP17BII+ was completly
recreated in C and is not a RPL calculator behind and has permanetly
allocated X, Y, Z and T registers. " that explained a lot. Is there
some place that I may read more about this on the web?
So the best that I can think about the HP-17BII+ is that it is a
faithful implementation of the HP-17BII?
However, I do think that this makes thinking about the [gold shift]
[R Down Arrow]
key and and the [gold shift] [x<->y] a little different than on
earlier RPN calculators especially after a [gold Shift] [Clr DATA] is
performed... at least to me. I can deal with it but, did notice it
right away. I wonder if this does not confuse new users more ...
especially long time HP-12c RPN users.
Thanks again,
Frank
Saturn rising
except that:
o Its *maximum* depth is 4.
o Once it attains a depth of 4, it doesn't shrink unless cleared
(fourth level instead replicates into 3rd level, as in older calcs)
"Roll Down" is equivalent to DEPTH ROLLD
"Roll Up" is equivalent to DEPTH ROLL
Does anything remain unexplained?
--
Off to count my moons...
Saturn rising
While depth < 4 [act like hp48/49/50]
While depth == 4 [act like all old "fixed stack" calcs]
Once depth == 4, it remains 4 until cleared.
Stack "rolling" is like DEPTH ROLL[D]
--
Human vs. calculator:
http://news.bbc.co.uk/2/hi/uk_news/magazine/6913236.stm
Human vs. other industrial machinery:
http://en.wikipedia.org/wiki/John_Henry_(folklore)
http://www.ibiblio.org/john_henry/ [real person?]
Christoph Widmer
lnxfdw schrieb:
You are indeed right, I reproduce the same behaviour. I was a little
misled by the fact that once you have entered four numbers into the
stack, it does not shrink any more until you do an explicit "Clear Data"
(at least as I experienced, being careful now! - as a lazy bum I
normally do not explicitely clear the stack, so it appeared to be a
normal four level stack). One your last note, at first this looks
strange, but it does not seem to make much difference (and stupid me
really did not notice until now).
Best regards
Christoph
lnxfdw
Fri Aug 17 11:18:14 2007
Re: HP-17BII+ RPN Mode "variable length stack" Views
To me this is the most valuable part of this newsgroup. You can look
at a subject through other eyes and get a different view than the
eyes you are looking through. I hope this doesn't ever go away.
For me, the below posts made sense and satisfied my
curiousity and gave me different ways to think about my collection:
.............
[*] The "New HP" at work in the 21st Century :-)
------------------------------------------------------------
(1) "the HP17BII IS indeed ... a RPL
calculator "
(2) "however the HP17BII+ was completly
recreated in C and is not a RPL calculator
behind and has permanetly allocated X, Y, Z
and T registers. "
[*] A Generalized Way Of Looking At HP RPN/RPL
Across Models/Years
-------------------------------------------------------------
While depth < 4 [act like hp48/49/50]
While depth == 4 [act like all old "fixed
stack" calcs]
Once depth == 4, it remains 4 until cleared.
Stack "rolling" is like DEPTH ROLL[D]
.............
I do think the above would make it harder for new users
and to have new users for RPN/RPL. But, that is an
HP problem that I hope they want to solve. I was really
curious as to whether this was a "feature" from the
"new HP" ... I liked the old one better but, we make do
with what we have.
Thanks again all of you ... for your time and