Changing Interest


My interest in calculators started from a science background when power series and Bessel functions were interesting. At that time when I saw a financial calculator I thought Amort was a dead person!

However, now I have a mortgage and have to buy cars and other expensive things I have found a new interest in financial calculators, my collection has grown to include:


HP-12C (old and new)

HP-10B (old and new)

HP-14B 50th anniversary

HP-17BII (brown bezel)


Commodore F4902

Car salesmen always look scared when I put one of these on their desk and check the repayments!

I would also like to get the financial modules for HP-41CV and HP-71. Can anyone help??



As your subject is "Changing Interest", may I suggest you
try and get a vintage Sharp PC-1421 Financial Pocket
Computer ?

You can have a look at it here:

It's a wonderful machine: very slim, lightweight,
metallic body, full alphanumeric dot-matrix display,
comes with 4 Kb RAM but admits extra RAM Cards, has an
I/O port to store/load programs on tape, or connect it
to a printer, etc.

But most importantly for your new interest, it
features a full array of financial functions (including
Internal Rate of Return, mortgages, date calculations,
anything) PLUS all usual mathematic functions and BASIC
language commands (i.e: trigs, logs, subroutines,
for-next loops, two dimensional arrays, long name
variables, string variables, etc).

Of course, all financial functions can be used
right from
the keyboard AND from BASIC programs !! :-) You can even
do machine language programming (PEEK, POKE, CALL) on the
machine itself (for instance to create and animate
graphics on the dot-matrix LCD), no accessories needed.

And, as a big plus, it's very fast, much faster than,
say, an HP-12C. Of course, with its memory, expandability,
speed, plus its powerful BASIC language extended with financial
commands, you can do real wonders with it, specially if
attaching a full-size line printer to it. Also, it has
continuous memory (of course), but the RAM cards with your
financial programs and data on them can be removed from
the machine or exchanged without losing their contents,
as well.

My advice: get one (eBay ?) fast, and you'll be delighted.
I certainly am with mine.


WHAT??? IS this heracy, recommending a Sharp maching in the HP site???


A few years ago, my wife and I were looking for a new car and one deal that a salesman gave us seemed too good to be true. I whipped out my HP 48GX and indeed it was too good to be true. Their deal maker had made an error.

The 48GX is indeed an amazing calculator!


One place I like to check occasionally is The Bull Cabinet ( Having just checked after reading your post, I see that they have the GMAC I, II, and III modules listed - No prices though.

Possibly Related Threads…
Thread Author Replies Views Last Post
  HP Prime Tip: Changing the Color of a Function Eddie W. Shore 3 1,581 10-02-2013, 04:08 PM
Last Post: Jim Horn
  About changing or deleting content after replies were made Raymond Del Tondo 1 1,122 08-26-2013, 05:01 PM
Last Post: Massimo Gnerucci (Italy)
  Article of interest Victor Quiros 0 919 03-09-2013, 03:56 PM
Last Post: Victor Quiros
  HP 12 C simple interest calcuation sam 6 1,996 01-16-2013, 10:22 AM
Last Post: fhub
  [WP34s et al.] Solving the TVM equation for the interest rate Dieter 24 5,930 12-01-2012, 05:53 AM
Last Post: Paul Dale
  Interest in CNC parts? Hugh Evans 11 3,085 10-11-2012, 12:50 PM
Last Post: Hugh Evans
  OT: Is a nonfunctioning TI-66 of interest? Peter Murphy (Livermore) 9 2,501 05-04-2012, 02:07 PM
Last Post: Howard Owen
  Changing radix mark on a 32E Matt Agajanian 8 2,493 04-07-2012, 04:59 PM
Last Post: Walter B
  Information that may be of interest to HP-75 users posted Paul Berger (Canada) 1 1,322 02-04-2012, 08:03 PM
Last Post: Geir Isene
  Interest in 32-bit version of User Code Utiltiy for HP-41 MichaelG 16 3,989 01-30-2012, 02:01 PM
Last Post: MichaelG

Forum Jump: