HP 28C Scientific Calculator from 1987 - A new beginning

This video is about the HP 28C, a strikingly innovative calculator that setup a foundation for HP's scientific calculators for a number of decades.
The 28C introduced an enhanced version of RPN, CAS and graphing capabilities to HP's scientific calculator line. It also introduced a new user-facing programming language called RPL.
In the video I mention an article of HP Journal that goes into a lot about the development of this calculator that is worth checking out:
- www.hpl.hp.com/hpjournal/pdfs...
For more calculator videos check out my channel / calculatorculture

[@jurjenbos228]

RPL is arguably the most advanced calculator programming language ever, both from the user and from the implementation viewpoint

[@SteveSim99]

Great video! Bill Wickes was the R&D project manager for the HP-28 and HP-48 series calculators. Around 1986 when Bill proposed designing a new advanced graphing scientific calculator with algebra capabilities, there was no budget available to develop an entirely new calculator like Bill wanted to do. Bill's choice was to either use the existing hardware of the HP-18C with its limited 2K of RAM (along with more ROM) or gamble and wait sometime in the future to see if management would approve a development budget for the hardware he really wanted to develop (basically the HP-48SX). No one at HP was certain how much of a market there was for an advanced scientific graphing calculator with algebra capabilities. HP allowed the team to test the marketplace using the already developed HP-18C hardware. When the HP-28C turned out to be a huge hit, they approved the budget needed for the HP-28S and then for the HP-48SX. I had each of them shortly after they came out and am still using my HP-48SX. P.S. The reason the HP-28C had only 2K of RAM is that the HP-18C hardware it was based on had two display driver ICs that each had 1K of RAM in them. There was literally no separate RAM IC in the HP-18C or HP-28C. This was sufficient for the for the HP-18C but very restrictive for the expanded functionality of the HP-28C. After the HP-28C turned out to be a huge hit, HP approved the budget needed to add a standard 8-bit interface to the Saturn Lewis processor needed to interface to an off-the-shelf 32K RAM IC. Still I found 2K useful for my needs in 1988. It allowed me to store dozens of small engineering programs that were labeled in soft menus. It was a huge improvement over the handful of programs I had in my HP-11C at the time.

[@CalculatorCulture]

That's a really great story and makes the 28C make a lot of sense in retrospect. In today's parlance you might call the 28C an MVP. Some aspects were a success (eg. enhanced RPN) and some were not so much (eg. clamshell form factor). It allowed HP to learn from the market and go on to make better devices.

[@hank1519]

I used to own one of these. It drove me nuts when it would crash in the process of graphing expressions like 1/x. 😊

[@SteveSim99]

Yes I remember having to turn off the Undo option (and other recovery options) to free up memory when performing some of the more intense operations.

[@perfectman3077]

@@CalculatorCulture I am still unsure about "enhanced" RPN. There are benefits to having a 4 level stack.

[@MattMcIrvin]

@@perfectman3077 Since the 28S (and Forth programming) were my introductions to stack-based calculation, the idea of a 4-level stack seems really confining to me.

[@jbecerrat]

A mis 66 años de edad, hoy miércoles 29 Junio 2022, por fin en mis manos una HP 28S a la que acabo de instalarle las baterías N alcalinas... y funcionando a la perfección luego de haber estado abandonada no sé durante cuántos años por su anterior propietario, es decir, casi literalmente, estaba entre la basura y un amigo mío la encontró y me la pasó..... ! Llevo unas cuatro horas estudiando el manual y a continuación este video.. y ya tengo deseos de programarla para el uso financiero! (soy administrador de empresas del siglo pasado..... y desde 1995 he estado utilizando la Palmtop HP 95 LX, luego la Palmtop 200 LX con 4 MB que aún utilizo para mis finanzas, anotaciones, inventarios, etc....). En fin, muy agradecido por este video tan excelente, felicitaciones. Saludos!

[@franz2383]

Felicidades! Envidia de la buena, yo vengo buscando una LX hace tiempo.

[@jbecerrat]

@@franz2383 Desde luego, estaremos de acuerdo que una HP 200LX es un dispositivo que supera muchas expectativas.... Pienso que se trata de una auténtica reliquia (algo así como un dinosaurio viviente) y pienso que, a mis 68 años, lo mejor sería que alguien la adoptara o heredara, mantenerla activa otros diez o veinte años... La tengo disponible para la venta, el problema es que estoy en Bogotá, Colombia, y ni siquiera me arriesgo a venderla por envío, sino en persona, para entregarla con los dispositivos, programas e instrucciones de uso actualizadas. Gracias por su comentario, saludos! (post data: también me gustaría obsequiarle la calculadora HP 28S a quien me compre la HP200LX...... por las mismas razones: auténticos artículos de colección, para que no queden olvidados y ojalá sigan siendo útiles o funcionales por otros veinte o treinta años...)

[@Essentialsend]

in my experience the only (but major) deficiency is the batteries. It is so hard to replace them without losing the buffer and with it everything which has been programmed

[@MattMcIrvin]

I still have my 28S somewhere. I actually loved the clamshell design (with the ability to fold the alphabetic keyboard back if you only needed basic calculator functions) and thought the vertical format of the 48 was something of a step back. That terrible battery door was a disaster, but otherwise it was a really cool physical design. Software-wise, I love the tight integration of it all, which brings a certain unity to this huge, complex collection of functions. Everything from an algebraic expression to a complex program to a graphical display can go on the stack; anything can go in a variable; programs can manipulate them all in the same way. The later models complicated that unity a bit by putting in new entry and menu modes intended to make things easier, but in the process, made it a little easier to get lost in a thicket of functionality.

[@aresmars2003]

A great review of a great calculator. I used my HP28C from 1987-2015 or so when it died, and then I found a 28S on eBay for $50 or so, which I still use. I agree the battery cover is problematic, but you just need a little care. I'd TOTALLY support an identical modern calculator, just add a USB connection to a computer for external storage, and a larger screen.

[@normansmith9110]

Very few comments so far. I remember seeing and wanting an HP28C. The biggest weakness of the HP28S was it's lack of an I/O interface. It got me ready for the HP48S which I used till I wore out the keyboard. I had an HP48G and I wore that keyboard out. Then I had two HP48GX calculators and mostly wore them out. Later I got some more out of a thrift store. In 2005 I got first an hp48gII and then an hp49g+. Later I got an HP50g. It's interesting how the calculators developed. The HP28 had only ten object types, real numbers, complex numbers, strings, real strays, complex arrays, lists, Global names, local names, programs, algebraics and binary integers. The HP48 added directories, libraries, unit objects, commands, functions, XLIB names, Library Data as well as a group of system objects, pointers, system binaries, backup objects, Code objects. The hp49 series would add even more, fonts, Minifonts, Symbolic Matricide and would add Flash pointers to the system objects. Out of the box it could create libraries something the HP48 could only do it a library was installed that could make other libraries. HP let developers know how to system program the calculator. There's more I could say but this comment is getting pretty long.

[@CalculatorCulture]

Thanks for all the detail on the successors to the 28C and it's interesting to hear your stories. Collecting calculators is a relatively new hobby for me and i'm always aware that there are people with decades of experience using these devices.

[@odarge]

Not very much comments ;-) but we like this calculator though, thanks to @calculator culture

[@carloscm1323]

Graphing calculator. Nice calculator with soft keyboard and a good display contrast.

[@JosephRawsonWorks]

I had a 28s

[@ZedAlfa.]

You need to do a vid on the HP 42S.

[@douro20]

I wish I could find one of these. I do have an 18C, though.

[@aresmars2003]

Lots of them are sold used on ebay now.

[@NuGanjaTron]

@@aresmars2003 Yeah, but prices have gone way up...

[@aresmars2003]

@@NuGanjaTron True! Probably an HP Prime is a better modern calculator, although seems annoying if batteries drain faster. My 28S can keep one set of batteries for many years.

[@danceswithdirt7197]

What a quaint little machine. Shame about the clamshell and the freaking 2KB of RAM though.

[@Crazytesseract]

Nice one! Sorry for interrupting but...Please help! fx-5800P, The N-queens program does not work.🙁 I used your program in the video. Where might have I gone wrong? After Goto 3, there is a in the program. Is it < or >? Neither of them works. Can you give a link to the program?

[@Crazytesseract]

I guess it was a 'not equal' symbol. Now it works after putting X-Y into parantheses.

[@CalculatorCulture]

You can enter the ≠ symbol by hitting the Function key then 3 for the Prog Menu. Next hit Down arrow and select item 2.

[@Crazytesseract]

@@CalculatorCulture Yes, done! Thank you.

[@pedrohernandezbanda1177]

Encontré una tirada en la calle

[@kellypainter7625]

They completely failed at the 1m drop. The battery door breaks every time.

[@leo.girardi]

By pumping numbers on the stack then evaluating, you are wasting keystrokes.

[@CalculatorCulture]

That’s true.