HP-25/25C Potential



#16

Hello all.

Along the lines of Peter Henrici's book, 'Computational Analysis with the HP-25 Pocket Calculator,' what is the most sophisticated program you've developed for the HP-25?


#17

In 1985 I created an HP-25 program to calculate the compass azimuth and elevation needed to manually aim a "portable" 5.5 foot satellite TV dish to point to the Galaxy I (or II?) satellite given your current Latiude and Longitude. It also had to take into account the true north magnetic declination of your location. I used this program to create a user friendly table that listed common cities throughout the U.S. Each entry had the name of the city with its Lat and Lon, along with the Elevation and Azimuth needed to aim the dish at that location.


This was my first job at a company named Boman Industries. This was part of the documentation for a portable satellite TV dish and receiver that they sold for RV use. No matter where you were camping in the woods you could still relax with TV :)

While it was not a complex program, it was a challenge getting the information needed to form the equations from library books. It is hard to remember how we had to research things before the Internet came along.

#18

Henrici's books is awesome!! I bought a copy back in the 80s. I recently found eBook versions on the internet. Henrici's wife wrote a version for the HP-33C to go along with a numerical analysis book that Henrici wrote. This version has programs that use GSBs. I am sorry that Henrici never wrote books for the HP-67 or the HP-41CX. I am consoled by the fine HP-41CX programs that Jean-Marc Baillard has written since they have the same quality as programs written by the late Henrici.

Namir


Edited: 9 July 2013, 12:15 a.m.


#19

Namir

I have a first edition of the 25 book but I was unaware of the 33 version. Do you still have the full title and author of same?
SlideRule

Edited: 9 July 2013, 2:32 p.m.


#20

Try these two books:
Essentials of Numerical Analysis with Pocket Calculator Demonstrations and Numerical Analysis: Demonstrations on the HP-33E.

I have a copy of the first but not of the second. I suppose I'll have to dig it out, give it another read, and write a review...


#21

Thanks for the references

Add Applied & Computational Complex Analysis - volumes 1 & 2 to the extant titles.

SlideRule

#22

Peter Henrici's Numerical analysis was my *favourite* book in my school years. Hungarian edition was the best choice of translators ever. This is a book about how to DO numerical analysis. +fav forever!!! :DDD

#23

.
Hello Matt:

Quote:
what is the most sophisticated program you've developed for the HP-25?

.
You can have a look at what I consider to be the most sophisticated program written for the HP-25 by following this link (7-page article, PDF format):

Long Live the HP-25C !

Best regards from V.


#24

Quote:
.
Hello Matt:

.
You can have a look at what I consider to be the most sophisticated program written for the HP-25 by following this link (7-page article, PDF format):

Long Live the HP-25C !

Best regards from V.


I love that article. Have re-read it many times and I've copied both programs to my HP-25 emulator (Go-25).
#25

Valentin, thank you for a tremendous article and programs! My first calculator was a '25 which my parents gave me as a EE graduation present a month after graduation as that is when it hit the market (June 1975, US$195). I used it very heavily for a year and my brother Joe was fascinated by it. When the '67 came out (1976), one replace my '25 which went to Joe. Someday I'll have to answer to St. Peter for doing that...

The '25 eventually died (fried ACT due to infamous battery charger design) and is in storage from a move. I hope to get it back someday and perhaps replace its main circuit board with an ARM equipped one running a simulator. I had hoped to replace the LEDs with current technology higher efficiency ones but nobody makes such a thing. Sigh.

Wonderful code - does a direct GTO memory of HP65 User Group / PPC days. Thank you again!


#26

Quote:
The '25 eventually died (fried ACT due to infamous battery charger design) and is in storage from a move. I hope to get it back someday and perhaps replace its main circuit board with an ARM equipped one running a simulator.
Wouldn't it suffice to take an AVR and maybe some shift registers? I thought about building something like that for my dead 25.

A LiPo rechargable battery would be nice, too :-).

#27

Gracias, Valentin, for pointing me to your article again. I had downloaded it in 2007 already but it is fun rereading it now.

d:-)

#28

Thanks Valentin! I really enjoyed reading that article again. The HP-25/C was really a price/performance breakthrough for the time and for a lot of people, it was their first programmable machine.

#29

I can't say enough how much I enjoy all of your great articles!

Not only do they show an incredible array of possibilities with various HP calculators, but they also bring me back in time to the period when these fascinating machines were amazing and delighting people with undreamed of possibilities.

When the HP-35 came out, I was using a bulky Monroe mechanical calculator at work with a carriage that moved back and forth and bells that rang like a typewriter. It would be a number of years before I'd get an electronic one at work, so it's not hard for me to get into that spirit of wonder that you write about of what the early HP calcs could do. For those of us who never got our hands on an HP-35 or HP-25, we are fortunate we can use emulators. But even better to have someone like you to take us by the hand through complex calculatons and to show how, with the right technique and imagination, one could turn the HP-25 into a supercomputer! Or solve polynomials on the HP-12C! Or perform numerical analysis on the HP-35!

I seem to remember seeing some of your articles back in the PPC days, 3 decades ago. I wish I had known you or had seen some of your writings when I bought my first electronic calculator back in 1975. I walked into the Calculator Department of Macy's Department Store, just knowing that I needed something with a memory. There were lots of calculators. At the high end were the HP's and TI's, with functions I didn't even know how to use and with pricetags that intimitated me. I settled on a modest thing at a fraction of the cost, with percent, square root and recriprocal functions and still came away amazed at what it could do. Had I been enlightened, I could have invested in a proper RPN machine, but little did I know. Just having a machine that kept track of the decimal point was a big advance for me. For a month I didn't trust my new acquisition so I double checked all my calculations by hand with pencil and paper just to convince myself that it was accurate. If I had tried, and had known how to use an RPN machine, it would have blown my mind.

When you wrote about how you were pleasantly surprised when you got your HP-25 that it could do even more than you ever dreamed of, I know that feeling and had it with my first HP.

I don't think the visionaries at HP could have dreamed of the limits to which the user community would push their creations.

Thanks for enlightening me and also for the wonderful trips down memory lane!

Sincerely,
Bob in San Francisco

#30

I'll have a refresh and look at the article again since it's been at least a year since I read it last. Thanks for the remind.


Possibly Related Threads...
Thread Author Replies Views Last Post
  Strange HP 25 Problem (Repair) Onur Ilkorur 5 357 12-06-2013, 05:13 PM
Last Post: Onur Ilkorur
  HP-25 Wayne Selway 1 172 11-22-2013, 12:58 PM
Last Post: Michael de Estrada
  Interesting Base Conversions - Porting a 1975 HP 25 Program to the HP 35S Eddie W. Shore 1 183 10-13-2013, 07:49 PM
Last Post: BruceH
  Later HP-25C Keyboard Repair aj04062 2 200 04-23-2013, 07:25 PM
Last Post: aj04062
  For sale: HP 25C and Stat Pac 2 for HP 65 Michae Altmann 1 190 04-21-2013, 01:24 PM
Last Post: Raymond Del Tondo
  Recharging original batteries in HP 45, 65 and 25 Michae Altmann 1 161 03-05-2013, 12:21 AM
Last Post: DavidShenk
  HP-25 keyboard Brad Barton 5 266 02-16-2013, 09:59 PM
Last Post: Brad Barton
  HP 65/25 shout-out in interview with Paul Lutus Egan Ford 3 210 12-21-2012, 11:09 PM
Last Post: Mike Morrow
  New HP-25 Emulator for iPad, iPhone, and iPod Namir 5 274 05-22-2012, 06:22 AM
Last Post: Mike (Stgt)
  11C's potential Matt Agajanian 7 311 05-14-2012, 08:26 PM
Last Post: Matt Agajanian

Forum Jump: