The HP-28 is no longer supported by HP. However, you will find support for
it on the http://www.hpcalc.org/ website, which is privately owned. Although
the site is mostly for the 48 and 49 series, you will find programs and
documentation supporting the 28S on the site.
I recently dropped my 48SX and after calling HP found that it can not be
repaired since they no long support it. Although there are some companies
that specialize in modifications and repairs of HP calculators, it gave me
the excuse I needed to upgrade the calculator to the 49G. Comparatively
speaking, the 48G is much more powerful than my 48SX and cost me less than I
paid for the 48 about 15-years ago.
One of the things I like about the 49 (or a couple of things) is the users
choice of algebraic problem solving or RPN. For quick number crunching RPN
is great, but for entering a deflection calculation, the textbook function
(which makes formula's look like they do in published text) and the
algebraic format is great - especially since you can edit a complicated
formula as though you were using a text editor instead of manipulating
The second thing I grew very fond of was the Units library. While the Units
library goes back to before the 48 series (or in your case the 28S series),
the 49G allows the user to attach the units to a number creating a "Unit
Object" and solving problems creating mixed units in the last unit entered.
Although I have not perfected my ability with this and am getting some mixed
results, when I follow the directions it works great. The downside is that
you need to either look up the unit and attach it to the number, or use
their crude text editor to attach it.
What you can also do (which is the reason for my enthusiasm) is to create a
custom menu that will list all of your commonly used units including the
creation of those that don't exist in the library such as plf, klf, ksf etc.
Once you do this, setting up an equation or manipulation of numbers with
units is as simple as pressing the number then pressing the unit on the
function key menu.
Similar to a palm computer, the 49G comes with 1.5-megs of RAM divided into
three or four ports, each with increasing protection against loss of
information. Users can create as many custom menus or programs as memory
will allow and store them in a folder (directory) structures similar to that
used by DOS. Whereas previous calculators allowed you to store one custom
menu into the CST variable, the 49G allows you to design many menus using
the CST variable and separating the variable into unique folders. The
features of the 49G are upgradeable flash bios (reported to be the last
calculator you will own) and there is a large support group such as the link
above, which creates a library of programs written for HP calculators -
including your 28-S.
FWIW, the 49G can be purchased from Costco for $154.99 plus tax and shipping
(through their web-page since the stores don't stock it). However, my wife
called CDW (Computer Discount Warehouse) and told them that it was
advertised on Costco's website. CDW sold it to her for $154.00 with no tax.
Shipping was $5.95 for standard mail (4-6 weeks delivery) or $10.99 for
Fed-ex overnight (my choice). Documentation could be better but web
resources are very good. The calculator comes with a 48-49 or 49-49 serial
cable to transfer user libraries (a computer serial cable is another $30.00,
but there is instruction on the website above for making your own cable from
Radio Shack parts for much less). There is no Infrared port - opinions are
that it is to prevent cheating on exams in schools where the calculator has
been approved for use (such as the SAT's) but this isn't such an
inconvenience since I never used the IR port of my 48SX.
The only questionable issues are slow speed (not really a big problem unless
your are a real power user) and the body style (color and buttons). I prefer
the rubber click buttons as my fingers don't slip, but the light blue body
takes some getting used to as does the slip on plastic cover (which took me
10 minutes to figure out how to remove when the calculator arrived).
Sorry, this was not intended to be an advertisement for the 49-G and I
really did mean to stick to your 28-S issue if there was support for it.
The Structuralist.Net has added a Programmable Calculator Forum for those
who wish to upload and download programs for the TI and HP programmable -
but then you might consider this a plug for the Structuralist, which you
criticized me for previously (just a light hearted comment, not meant to be
In closing, if you are considering upgrading to the 48-G or GX - I would
seriously consider the 49-G which is less than the 48-GX and more powerful.
Dennis S. Wish, PE
The Structuralist Administrator for:
(208) 361-5447 E-Fax
ICQ # 95561393
From: Speck, Todd M [mailto:tmspeck(--nospam--at)pbsj.com]
Sent: Sunday, January 07, 2001 12:30 PM
Subject: HP Calculator Programming, Feet and Inch Decimal Conversion
I have an HP-28S calculator. I would like to be able to input feet and
inches and convert them to decimal feet with as few key strokes as possible.
Does any have any programming for an HP-28S or compatible programming for
said HP to enable feet and inches to be entered in as numbers, and
automatically converted to decimal feet?