Why is the 28S so cheap?



#14

I am considering a 28S as my travel calculator. I like the 4 line display and am not religious about RPN vs. RPL. I also like that it is self-contained, i.e. the calculator is the case.

I see only positives, so why are they so cheap? Is there a problem with the hinge? Battery life or performance?

Does the 28S support bidirectional transfer? It is important that it does not.

Thanks.


#15

The 28S is cheap as it's not considered as valuable classic as previous calculators, even if its far more powerful.

In the past, when the 32SII was still for sale, it reached $10 to $20. When HP decided to withdraw this model, the price suddenly jumped and reached sky high prices often higher than the 42s.

#16

Forgive me for hijacking the thread, but I have been watching this one, and could use some advice:

http://cgi.ebay.ca/ws/eBayISAPI.dll?ViewItem&item=9726259936&sspagename=ADME:B:AAQ:CA:1

I am a bit concerned that the seller can't tell us whether it works or not. Is he saying it turns on, but he doesn't know what to do with an RPN unit? Also, the fact that there is nothing in the display in the sole fuzzy photograph.

I am interested, but not in a fixer-upper. The seller hasn't got back to me regarding my queries into a more detailed description of the item. The fact there is one lonely low bid and no reserve makes me wonder....

Opinions?

Les


#17

Hi Les,

IMHO i would not consider a BID where someone says they do no know how to operate a Calc or get it to work. Seek out the HP28s that are listed with unbroken battery doors (weak design) and squak-free hinges. I think the squaking can be resolved with a little silicon lube. There is lenty of reference guides, manuals available. It is a marvelous machine if you can find a mar free decent one at a good price.

Warmest regards,

Andy
RPN power user and Vintage TI AOS owner

#18

It looks like he was able to test the HP-18c!

Joao

#19

The hinge, or rather the flex circuit that connects the left-side keyboard to the rest of the calculator, can break, and when that happens, you're stuck. The clamshells are essentially unrepairable.


The infrared is unidirectional. If you don't mind RPL, the 28S is a nice calc, but most RPL users prefer the 48 series, mostly because of the bidirectional I/O and expandability, I suppose.

- Thomas


#20

The 28S has an outstanding advantage over 48xx/49xx: its separate alpha keyboard.
Its so efficient to write programs without natigating into menus to enter such common commands as IF THEN ELSE END.

I have been using it for 15 years new, opening the hinge 4-5 times a day all over the year without any damage.
I am seriously considering buying a backup in case of mishap, but I really do recommend this calc.

Also check the display: I have seen 2 versions, one with a glossy display, and one with an anti-glare layer that is admittedly more readable.


#21

I, too, love the 28S and its separate alpha keyboard (albeit clunkly to use with one hand) since I like to program on the calculator. In my opinion, the newer 48/49 series tend to promote programming on a computer and then transfer the program to the calculator. People who are okay with that don't mind, but they miss out on the intuitive and easy to remember menu layout of the 28S.

Quote:

Also check the display: I have seen 2 versions, one with a glossy display, and one with an anti-glare layer that is admittedly more readable.


I think the glass (glare and all) display version is even more valuable, since they tend to be earlier "Made in USA" units. How rare is that nowadays?

I'm not sure if the 28S is cheap. If you mean eBay sales, prices tend to go up and down (change in the weather?). Who knows the real reason why.

John

#22

Quote:
I am considering a 28S as my travel calculator. I like the 4 line
display and am not religious about RPN vs. RPL. I also like that
it is self-contained, i.e. the calculator is the case.

Well, genuine leather cases are available, although closing a
clamshell model does offer a lot of protection to the keyboard and
display.

Quote:
I see only positives, so why are they so cheap?

Well, it helps when something isn't categorized well, like
this
one
. :-)

But seriously, "Classic RPN" aficionados usually aren't interested
because the 28 series are RPL, and most RPL users prefer the 48 or
49 series.

Quote:
Is there a problem with the hinge?

I've often thought and read that the flex circuit for the hinge
could break, but I don't believe that I've ever read of that
actually happening.

The hinged design can seem a bit clumsy, but as Bruno noted, it
makes it a lot easier to type in commands without hitting the
ALPHA key all of the time. By the way, even with the 48 and 49
series, I often find it easier to simply type in the command
rather than using the menus.

Quote:
Battery life or performance?

I suppose that a "typical" battery life would be maybe six months.
To me, the performance is adequate for most tasks.

The batteries are a nuisance to change, and apparently since most
users won't want to risk a "memory lost", they're often in a rush
to get the fresh cells in, hence the frequent reports of broken
battery covers, or even the case at the battery cover. The "N"
cells are also somewhat unusual, so a "fresh" cell may have been
"on the shelf" for a very long time. The "N" cells tend to be a
bit expensive too.

Quote:
Does the 28S support bidirectional transfer? It is important that
it does not.

No, the 28 series IR is unidirectional, only for output to a
printer, and the encoding of the bytes is unusual. See the
HP
82240B Infrared Printer Technical Interfacing Guide
if
you're interested in the details of the IR output.

"Wired" I/O isn't built-in. There have been "hardware hacks" to
add bi-directional I/O (RS-232 compatible, IIRC) to the 28 series,
but once the 48SX became available, there wasn't all that much
interest in "fixing" the 28 series.

The biggest problem that I have with the 28 series is that the
only way to restore a "saved" (to a print-out) object is by keying
it in all over again.

The 28 series lacks some commands available in the 48 and 49
series, and they aren't expandable as the 48SX, 48GX, and 49g+
are. Note that RPL objects take more memory than the (more or
less) equivalent objects in "Classic RPN" calculators, so even
"32KB" can be a bit limiting.

Regards,
James


#23

My first HP was a 28S that I spent all of my time with programming, etc. It was a great calc. The only issues I can see one having with it would be

(1) battery door / battery replacement ... I lost all my 30k-worth of memory due to this and not getting batteries replaced quick enough

(2) It's not as handy to use as the smaller calcs. It's pretty much limited to desktop use only, and if you're in a classroom that actually allows you to use it, there's hardly any room on the desk for it once you open it up. If used as a dedicated desktop, it's easy to enjoy.

(3) Anyone who used the 28S envied the 48 owners when they hit the market. As a physics major back in 1989, I got my 28S for Christmas. Shortly thereafter the 48SX hit the market, and then the 48GX. I was one of many 28S users that would have bought the 48GX if I had the money at the time. (Now I have a NIB 48GX.) The 48GX was a much better machine in every aspect that when folk look back on those days, they don't think of the 28S and how it was king of the hill for a year or so, they think of how powerful the 48GX was and still is, and the countless programs written for it. This keep the GX prices high and the 28S prices, well, low due to lack of interest being in the GX's shadow.

#24

Egan --

I think that James, Stephen, and Thomas provided the answers to your question. Even disregarding the issue of RPN vs. RPL, the HP-28C/S was not a worthy successor to the HP-41, mainly due to the following:

  1. Lack of expandability
  2. Lack of hard-wire I/O and limited infrared I/O
  3. Lack of a clock and calendar functions

The HP-48S fixed deficiencies 2. and 3., and added more capabilities, a bigger screen, and better graphing. The HP-48SX provided the expandability.

The original HP-28C's 2 kB of RAM was not up to the task of executing its own built-in functionality, and lacked directories and some mathematical functions (e.g., COMB and PERM) The HP-28S with its 32 kB RAM fixed those problems. However, the microprocessor in all "genuine HP" 28/48/49 RPL models can't always keep up with the demands of the advanced functionality built into these models. When the stack contents get complicated, commands execute with annoying slowness.

There are two things in particular to like about the HP-28C/S: The dedicated, easy-to-read keyboard for alphanumerics, and the unit library with definitions and dimensions. Athough units cannot be attached to values, the library is very nice to have.

-- KS


Edited: 17 May 2006, 11:24 p.m.


#25

Quote:
Lack of a clock and calendar functions

Actually there's a built-in clock.
You just need a SYSEVAL to get the value and display it as you wish.
I don't have the SYSEVAL address at hand, but it's classical.


#26

Bruno --

Quote:
Actually there's a built-in clock. You just need a SYSEVAL to get the value and display it as you wish. I don't have the SYSEVAL address at hand, but it's classical.


I did not consult my HP-28C manual before posting, but, by "clock" I meant a time and date display - "wall clock" -- not a timer input. The HP-41 Time Module (built into the HP-41CX) offered the time and date display, as did the HP-48. The HP-28C/S lacked this feature, to my knowledge, although it might be possible to write an elaborate program for it.

-- KS


Possibly Related Threads...
Thread Author Replies Views Last Post
  Cheap hp32sii in bad condition on sale on Taobao Waon Shinyoe (China) 1 776 03-01-2013, 08:35 PM
Last Post: Raymond Del Tondo
  Cheap rare HP35 and HP65 report Waon Shinyoe (China) 4 1,249 02-20-2013, 08:47 AM
Last Post: Frank Boehm (Germany)
  Riemann's Zeta Function (HP-28S) Gerson W. Barbosa 8 1,632 02-03-2013, 03:23 PM
Last Post: Gerson W. Barbosa
  28S Pi Functionality Matt Fegenbush 3 939 10-17-2012, 02:15 AM
Last Post: Nick_S
  HP-28S plays "Happy Birthday" Kevin F 0 594 08-06-2012, 04:53 PM
Last Post: Kevin F
  HP-28S Mathematical Applications manual errata Tom Sauntry 2 825 07-25-2012, 09:54 AM
Last Post: Tom Sauntry
  HP-28S Syntax Errors William N Strew 7 1,604 07-15-2012, 05:09 PM
Last Post: Luiz C. Vieira (Brazil)
  A cheap HP41C for sale...........999 EURO only aurelio 4 1,116 06-04-2012, 03:46 PM
Last Post: jerome ibanes
  50G<-->28S SYSEVAL map Matt Agajanian 3 1,024 05-29-2012, 03:28 PM
Last Post: Christoph Giesselink
  HP-28S Battery Cover Kerem Kapkin (Silicon Valley, CA) 2 1,055 04-09-2012, 10:29 PM
Last Post: aj04062

Forum Jump: