In defence of a 4 stack



#8

I found the 4 stack no limitation in the real world. It makes possible the repeating t register which I really took advantage of.
When you have 3 memories like the original 35 you have to squeeze what you can out of few resources. I used the t register to store
Resistance in a divider ans solved for the divider fraction and the output resistance. My solution has no precedence but it works.
I used 2(Pi)F repeatedly fo solve the resonance equation at a fixed frequency. 2(Pi)F multiplied twice by L or C and invert to see the resonant element. I used it similarly for 2(Pi)FRC-1 to solve RC corners for compensation of Op amps.
I note a dearth of younger and older MOHPC members around the central cluster. TI in the classroom? Too bad HP abandoned the field. Sam


#9

Hello Sam,

for sake of clarity please note a repeating t register is not bonded to 4 level stacks, but may also be present with any other fixed stack depth. Having 6 stack registers, x y z 4 5 t for example, will allow you all the tricks you do with 4 levels PLUS straight forward computing of more complicated equations than a 4 level stack can take.

Best regards,

Walter


#10

True but I find it very difficult to keep tabs with more than 4 stack registers at a time... my brain isn't what it used to be, it seems. Four works like a champ.

Best,
ÁM


#11

Buenas dias Ángel,

Quote:
True but I find it very difficult to keep tabs with more than 4 stack registers at a time

May I point you to another post?

Your preference may depend on the dominant use of your calculator: If it's stack gymnastics, I agree 4 levels are enough, but if it's number crunching, a few (!) more levels are beneficial. That was why I vote for a settable fixed stack depth. 4 levels in vintage mode and e.g. 6 or 8 levels in power mode.

Cordialmente,

Walter


Edited: 24 Feb 2009, 1:42 a.m.


#12

Walter:

You wrote:

Quote:
Your preference may depend on the dominant use of your calculator: If it's stack gymnastics, I agree 4 levels are enough, but if it's number crunching, a few (!) more levels are beneficial. That was why I vote for a settable fixed stack depth. 4 levels in vintage mode and e.g. 6 or 8 levels in power mode.

I would suggest different set of options for the stack:

1. An infinite stack such as on the 28 and 48.

2. A settable stack depth with the vintage type of t register replacement at the top, but not because I would personally use it.

How did HP choose the four level stack mechanization? Was there some sort of efficiency study at the time the 35 was designed, or was it mostly a matter of memory limitations?

Palmer

#13

designnut,

Would you share with this mathophobe/mathoklutz (mathsophobe/mathsoklutzo) your keystrokes
for those electronic formula?

Thanks,

Ren

dona nobis pacem


#14

http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/articles.cgi?read=701
Nobody responded to this. The resistive divider solution is novel. It was discovered by playing with numbers. Yes I amuse myself at times with calculator tricks. When I was faced with limited calculator resources I rewrote the classic EE equations to be amenable to the calculator. It gave me the horrors seeing people program solutions that were patently straightforward to me. With the HP65 I set out match many curves in books and succeeded. For thermistors I found if I added a large number to the temperature and used Ln with a few constants I found an easy match to the resistance VS temperature curve. I used repeated trials to correct my constants. I think we are needlessly hampered by packaged solutions, but they have their uses. http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/articles.cgi?read=780 E. Samuel Levy (google it) designnut@cox.net


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