HP 28S Hewlett Packard Scientific Calculator-Working New Batteries

sarahwinters
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Located in: Tulsa, Oklahoma, United States
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eBay item number:236180708462

Item specifics

Vintage
Yes
UPC
0088698000106
Brand
HP
Model
28S
Category

About this product

Product Information

The HP-28 is a series of scientific calculators introduced by Hewlett-Packard in the late 1980s. The first model was the HP-28C. It was released in 1987 and had only two kilobytes of RAM or random access memory. A year later, HP released the HP-28S model, the second and last in this particular line. This was a more advanced scientific calculator and had a capacity of 32 kilobytes of RAM. These were among the first scientific graphing calculators, which means that they had the capacity to solve calculations graphically. The HP-28S became the more common and popular calculator of the two. It is a lightweight handheld scientific and graphing calculator that weighs in at a mere 7.2 oz. It is pocket sized and offers just the right balance between power and ease of use. It has a simpler menu structure yet still provides multiple programming options. The display is 137 x 32 pixels with a dot matrix, monochrome LCD. This allows for four lines of data to be displayed on the screen. The calculator provides direct entry for algebraic formulas and an RPN input logic for interactive calculations. The information is displayed in a dynamic way with infinite stack viewing. This calculator performs a number of specific functions. You can perform algebraic manipulation, which means symbolically solving equations for any variable. You can do calculus, calculating derivatives, and definite and indefinite integrals. You can also solve math linear equations and perform binary bit manipulations. Users can calculate single and paired-sample statistics and probabilities and plot them on a graph. Finally, you can make unit conversions using any of the 120 built-in unit combinations.The 28S uses a regular battery, so you don't have to invest in special batteries. It has a protective clamshell case that flips open and comes in a variety of colors. The left side of the cover features a QWERTY alphabetic keyboard, while the right side features a regular scientific calculator keyboard. The unit has a regular key size. The power comes from a custom chip containing an improved Saturn processor core that runs at 1MHz. This new mini processor was so special that it was given a codename of Lewis. Each style of processor had a particular name taken from the Lewis and Clark expedition. Each provided something innovative, and this one provides the user with a file directory system. This is used for filing variables and storing functions and programs to use later. The HP-28S calculator offered a series of firsts. It was the first to offer RPL, or Reverse Polish LISP, as its programming language and was the first scientific calculator capable of symbolic computation. Even with all the capability, the 28S is simple to operate. There are four editions of manuals that you can use as guides. With these innovations, the HP-28S is a reliable device for solving advanced equations.

Product Identifiers

Brand
HP
UPC
0088698000106
Model
28S
eBay Product ID (ePID)
166527924

Additional Product Features

Power Source
Battery
Size
Pocket
Key Size
Regular
Type
Scientific

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sarahwinters

100% positive feedback•984 items sold

Joined Nov 2016
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4.8
25 product ratings
  • 21 users rated this 5 out of 5 stars
  • 4 users rated this 4 out of 5 stars
  • 0 users rated this 3 out of 5 stars
  • 0 users rated this 2 out of 5 stars
  • 0 users rated this 1 out of 5 stars

Would recommend

Good value

Good quality

Most relevant reviews

See all 15 reviews
  • by kw043087
    Nov 06, 2017Top favorable review

    My favorite HP Calculator

    My original HP 28S from 1988 died a couple of years ago. I've been trying to get by with an HP 48GX simulation app on my phone but I missed the tactile feel of the keys and the muscle memory of almost 30 years using the 28S. When I found a used 28S in good condition (the battery covers are susceptible to breaking) I jumped on it. I just wish that I would've bought a replacement sooner.

    Verified purchase: YesSold by: eelpoint

  • by ericoserravite
    Apr 27, 2016

    One great calculator

    This calculator is the beginning of a brave new world for Hewlett Packard scientific ones. New way of programming, viewing the "infinite" stack, graphing capability and much more. This calculator took HP to a new level beating all others. You must get one HP 28s if you can.

    Verified purchase: YesCondition: Pre-OwnedSold by: chenzo462

  • by gZmH5O9QTpW@Deleted
    Oct 10, 2017

    Great calculator

    My 30-year old HP28C died recently, the best calculator ever, except for the 28S upgrade, which has more RAM, so I was happy to find the 28S online used, and seems in great condition, manuals as well. I can't possibly list a fraction of the features of the calculator, but having a full alphabet keyboard is great even if you have to get used to it being in alphabetical order. A friend said no one needs calculators since phone apps can do it all, but that's simply not true, and having a dedicated calculator is simply more convenient than finding apps, and friendlier than touch screen buttons.

    Verified purchase: YesSold by: milo2015

  • by hupsters
    Apr 05, 2018

    . No need to learn a new calculator at this point in the game.

    The 28s dates to about 1990. This is my third or fourth one of these. Bottom row of keys quit on the last one. I just buy another one when this happens. This particular one was hardly used.

    Verified purchase: YesSold by: rmvr2004

  • by libertybasic
    Jan 01, 2020

    The HP28S is a legitimate pocket computer

    This is a great calculator. It takes the RPN concepts and brings them forward into a Forth-like programming experience. It is also more compact than the newer HP48 type calculators and has a dedicated alpha keyboards.

    Verified purchase: YesCondition: Pre-OwnedSold by: davidsmout

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