My little pocket calculator museum
Texas Instruments
With 960 program steps, or (alternatively) up to 99 memory locations it was a pretty capable device to begin with. Programs were stored on magnetic cards, which were drawn through the calculator by a small motor beneath the display.
Obviously the TI-59 lacked an alphanumeric display. All information had to be squeezed into a row with a maximum of 12 digits. But the competition, in particular Hewlett-Packard, was not different. More on that later.
Texas Instruments offered extensive program collections on magnetic cards and in small ROM modules that were inserted into a slot on the back of the unit. As students, we could not afford such things, of course. So we had to program everything by ourselves.
For the university something better was needed and so the TI-95 as a direct successor of the TI-59 arrived 1986 just in time.
Although it lacked a magnetic card reader there was a lot of memory (8 Kbytes, expandable to 16 KBytes) and an alphanumeric display. Five individual displays showed the current setup of the function keys.
ROM modules were back again. Especially great was the math library with numerical solvers of nonlinear equation systems (up to 8 equations solved with the Newton method) and of nonlinear differential equations (up to 9 first-order equations solved with Runge-Kutta method). That was unique not only for 1986: It should take about another 20 years before another pocket calculator from Texas Instruments had similar numerical skills.
Memory was available in abundance (28 KBytes) and there was even a port for data exchange with a desktop computer. But magnetic cards and ROM modules were gone.
TI had acquired the well-known computer algebra system (CAS) "Derive" which was made by the Hawaiian company Soft Warehouse and implemented it in a calculator. From there on, "solve (2x-4y = 6, x)" would no longer give "Error: Undefined variable" but "x = 2y +3" instead.
The picture shows the Voyage 200, the last and most powerful pocket calculator from Texas Instruments in this series. It was released in 2002.
Maybe it was the rather low speed (clock frequency up to 12 MHz) or problems with component supply. In any case, in 2007, the TI-nspire with a modern ARM processor and clock frequencies around 100 MHz was introduced to the market. The computer algebra system was again expanded significantly and updated operating system versions appear at regular intervals.
In 2010 the second, still current version of the TI-nspire followed. This device can be seen on the right.
The gain in speed of the TI-nspire over older models is striking. And also memory is now available plentiful: 32 MB of ROM and RAM each should be enough for a pocket calculator.
What will the future bring ? It seems obvious: The next step are calculators with backlight color displays.
Although the TI-nspire has a relatively high resolution (320x240 pixels) and can display 16 gray levels, the screen can hardly bee seen in dim rooms. Anyone who ever had an iPhone in their hand knows where the journey leads. CASIO has already announced the FX-CG20 to appear in 2011. As with many innovations before, Texas Instruments is certainly going to present an answer a few years later.
Although the TI-nspire has a relatively high resolution (320x240 pixels) and can display 16 gray levels, the screen can hardly bee seen in dim rooms. Anyone who ever had an iPhone in their hand knows where the journey leads. CASIO has already announced the FX-CG20 to appear in 2011. As with many innovations before, Texas Instruments is certainly going to present an answer a few years later.
Texas Instruments is not the only manufacturer of high-quality programmable calculators. Especially another American manufacturer, the Californian company Hewlett-Packard is (or was?) in tough competition with the Texas challenger.
Hewlett-Packard
For us students it was not an issue in 1981: HP computers are designed for engineers and eternity - and they cost accordingly. So half the math course used a TI-59 and we were convinced of having the superior product.
After a few years at the university my curiosity became so great that I got myself a small HP calculator. Shortly afterwards I was seized with the "RPN" virus (RPN = Reversed Polish Notation) and that has continued until today. Over the years, many old and new HPs were added to my collection.
But first a few words on RPN: HP computers are known to be different. Instead of the familiar algebraic notation "2+3=" the reverse Polish notation is "2 ENTER 3 +". The name comes from a Polish mathematician who invented this notation - but the other way around (hence the 'reversed').
To be honest: In the beginning Hewlett-Packard used RPN due to lack of storage and computation capacity. In algebraic notation intermediate results and parentheses-levels need to be stored during the calculation. The first pocket calculators simply didn't have enough memory to do this. Of course, storage was no problem any more in later models but RPN remained.
Texas Instruments even produced a software ROM-module for the TI-59 which emulated RPN on that calculator!
But what is so fascinating about RPN even today? The above example is much too simplistic to see this. In brief: RPN follows the human approach to solve complex formulas by working from the inside out. This is like mental arithmetic with calculator support. After a short learning period, RPN becomes very intuitive, lightning fast and extremely flexible. There are no hidden intermediate results, nor a vast number of open parentheses. With RPN an experienced user receives the correct result in the first run. With Texas Instruments calculators I have always repeated the calculation when it mattered and I often found errors. And this was certainly not due lack of practice on my side ...
With the current generation of graphics calculators, which display the entire formula before calculating, RPN has lost importance. But for quick calculations it is still unbeatable.
After a few years at the university my curiosity became so great that I got myself a small HP calculator. Shortly afterwards I was seized with the "RPN" virus (RPN = Reversed Polish Notation) and that has continued until today. Over the years, many old and new HPs were added to my collection.
But first a few words on RPN: HP computers are known to be different. Instead of the familiar algebraic notation "2+3=" the reverse Polish notation is "2 ENTER 3 +". The name comes from a Polish mathematician who invented this notation - but the other way around (hence the 'reversed').
To be honest: In the beginning Hewlett-Packard used RPN due to lack of storage and computation capacity. In algebraic notation intermediate results and parentheses-levels need to be stored during the calculation. The first pocket calculators simply didn't have enough memory to do this. Of course, storage was no problem any more in later models but RPN remained.
Texas Instruments even produced a software ROM-module for the TI-59 which emulated RPN on that calculator!
But what is so fascinating about RPN even today? The above example is much too simplistic to see this. In brief: RPN follows the human approach to solve complex formulas by working from the inside out. This is like mental arithmetic with calculator support. After a short learning period, RPN becomes very intuitive, lightning fast and extremely flexible. There are no hidden intermediate results, nor a vast number of open parentheses. With RPN an experienced user receives the correct result in the first run. With Texas Instruments calculators I have always repeated the calculation when it mattered and I often found errors. And this was certainly not due lack of practice on my side ...
With the current generation of graphics calculators, which display the entire formula before calculating, RPN has lost importance. But for quick calculations it is still unbeatable.
HP-35 The electronic slide-rule (market launch 1972)
Hewlett-Packard already had great success with programmable calculators in the late 60's. But these devices were monstrous, often larger than a typewriter, and prohibitively expensive for private individuals. This gave rise to the idea of developing a pocket sized calculator, which could also compute logarithms and trigonometric functions. Until then, pocket calculators were only capable of basic arithmetic.
It is rumored that owner Bill Hewlett himself asked his engineers in 1968 to develop such a device - against the advice of his marketing people that strongly doubted the commercial success of a scientific pocket calculator.
The HP-35 was finally released in early 1972 and became a best seller. It laid the foundation stone for the era of scientific calculators and made the then famous slide rules obsolete.
The name "35" came simply from the number of keys. Later models, however, were named by other criteria.
I was able to get my unit a few years ago in very good condition through a classified ad from a guy who didn't seem to know what a treasure he had.
The Classic family (market launch 1972-76)
Driven by the success of the scientific HP-35, Hewlett-Packard started to develop a sister unit for the businessman. The HP-80 was presented in the following year and introduced annuity calculation.
Then, the HP-35 was revised. His successor, the improved HP-45, was released in early 1974.
That changed in 1974 with the HP-65 (video available), which appeared in a record time of just 18 months after the HP-35's introduction.
The HP-65 could hold 100 lines of keyboard commands and 9 intermediate results. Because memory was erased when switching off the calculator, Hewlett-Packard invented a miniaturized magnetic card reader: Plastic strips coated with magnetic powder were drawn through a slot from the right to the left side of the device. A small electric motor ensured a uniform transport speed along the read head.
Unfortunately, the pressure rollers are made of soft rubber which disintegrates over the years. Today it is difficult to find a calculator with a magnetic card reader in working order.
As revolutionary as the HP-65 was: With 100 lines of code programming was still very limited. There were few jump and compare instructions available. Also, it was difficult to edit a program after it was entered.
In parallel the functionally identical HP-97 (video available) was released. But it was designed as a small desktop calculator and even included a thermal printer.
These calculators challenged Texas Instruments to introduce the TI-57/58/59 models in the following year with a printer as an optional separate unit.
The HP-67/97 had 224 program steps and 26 memories for floating-point numbers, and became one of the most popular pocket calculators of the 70s.
It's big competitor, TI's 59, had more storage (960 program steps or up to 99 memory registers) and was a lot cheaper - but it was released 10 months later and technical development was rapid at that time.
When I took my first industrial job in 1995, we still had several HP-97 in daily use in the technical office of the company. Anyone who has worked with such a device can certainly understand that.
The Woodstock family (market launch 1975-77)
Named after the famous cartoon character (and not after the festival) Hewlett-Packard started the introduction of a second family of calculators in 1975. Although smaller, more convenient and less expensive than the devices of the Classic series, the various models of the Woodstock family were still powerful.
The HP-25C in 1976 was remarkable: It was the first pocket calculator that didn't loose memory after switching off the power. Hence the "C" in the name: "Continuous Memory".
Magnetic card readers were neither available for these models nor for the next generation.
The Spice/Spike family (market launch 1978-79)
The rapid succession of new calculator families reveals the gold rush atmosphere of that time.
Back in 1978, with the HP-31E, the first representative of the new generation of Spice calculators appeared. It was not programmable, but exceptionally cheap with just $ 60 sales price.
The HP-34C was the scientific top model of this era. It was released in 1979 and could hold up to 210 program steps or alternatively 20 data registers.
A new and special feature of the HP-34C were the built-in numerical solvers for zeros and integrals of functions.
The HP-41 (market launch 1979-83)
When it was introduced in 1979, the HP-41 created it's own era. It was the first device with an alphanumeric liquid crystal display and had four slots for expansion cards.
Over the years, the HP-41 was followed by improved updates: HP-41C, HP-41CV, HP-41CX. The production of the last model was continued until end of 1990.
The slots could be equipped with additional memory, ROM modules, a magnetic card reader, a bar code reader and much more.
In 1981, the HP Interface Loop (HP-IL) arrived: A small computer network to retrieve data from measurement instruments and connect printers and plotters. With this network the HP-41 was used in schools and laboratories to carry out physical or chemical experiments automatically.
Like so many other ideas also this one was later taken up by Texas Instruments. Even to date (2011), TI offers data acquisition systems and sensors for their calculators that are specifically designed for school experiments.
The HP-41 practically meant the end for the great TI-59.
Later on, Texas Instruments developed a comparable calculator, the TI-88, but decided not to bring the device on the market.
It would have come too late (1982) and couldn't oppose the now vast ecosystem of the HP-41.
There are just a few prototypes of the TI-88 left and these are virtually impossible to find and achieve top prices. Unfortunately I do not have a unit myself - the picture on the left was taken from the Internet.
Later on, Texas Instruments developed a comparable calculator, the TI-88, but decided not to bring the device on the market.
It would have come too late (1982) and couldn't oppose the now vast ecosystem of the HP-41.
There are just a few prototypes of the TI-88 left and these are virtually impossible to find and achieve top prices. Unfortunately I do not have a unit myself - the picture on the left was taken from the Internet.
The Voyager family (market launch 1981-82)
These calculators were very handy (much smaller than the HP-41) and intended to replace the classical models. All units had an easy to read liquid crystal display and permanent storage. Over the years 1981/82 five models were released. One of them, the HP-12C, is still produced and sold new even today (2011)!
Among engineers, particularly the scientific flagship HP-15C has acquired a legendary status.
The calculators of the Voyager family were not expandable and they had no magnetic card reader or printer. Programs had to be typed in by hand when needed. It was difficult to manage multiple programs in memory.
Portable Computers
Then in 1982 came the HP-75: A bulky device mainly for commercial use in POS systems, inventory, for field staff etc..
The HP-75 can be used as an appointment reminder and has a text editor (on a line by line basis!) - similar to modern PDAs.
Also, the HP-75 has a manually operated magnetic card reader. Each of the two tracks can hold 650 bytes of data. That's a lot compared to the HP-65, but a ridiculously little in relation to the device's memory (16 Kbytes RAM and 48 Kbytes ROM).
The picture on the left shows a HP-75 in the expansion chassis with built-in phone modem with the bar code wand.
All previously released pocket computers were programmed in the so-called key code: the user simply typed the buttons in the order that was required by the formula. All keystrokes would be recorded and could be played back later. There was also conditional jump instructions to create loops. In 1982, this changed radically with the HP-75, as this calculator understood the popular BASIC programming language.
FORTH and even assembly language ROM-modules for the expansion port were offered and well documented.
The HP-71B was the last calculator with a magnetic card reader as an option. The magnetic cards were like the HP-75's and much longer than in previous devices (they also stored a lot more data). The cards had to be pulled by hand through the reader that was located to the right of the display.
The HP-71B came with 64 Kbytes ROM and 17.5 Kbytes user available RAM. It was better equipped than many home computers of the time. Just like a HP-41 the HP-71B could also control devices on the HP Interface Loop (all types of external printers, plotters, and measuring instruments) - but with 25 times the speed!
Unfortunately, this machine was missing the first time the popular UPN-calculator mode, because who would have a BASIC computer is not simply the right thing.
For the HP-71B Hewlett-Packard developed a new 4-bit processor architecture, called the Saturn chip, which was used in all pocket calculators in the following decades by the manufacturer. Only with the HP-49g + in 2003, it has been replaced by the modern ARM processor platform.
Unfortunately, this machine was missing the first time the popular UPN-calculator mode, because who would have a BASIC computer is not simply the right thing.
For the HP-71B Hewlett-Packard developed a new 4-bit processor architecture, called the Saturn chip, which was used in all pocket calculators in the following decades by the manufacturer. Only with the HP-49g + in 2003, it has been replaced by the modern ARM processor platform.
The Clamshell family (market launch 1986-91)
The first model of the clamshell family was the business calculator HP-18C. It was introduced in 1986 and had a radically different design than previous calculators.
Its scientific brother, the HP-28C, was launched in 1987 on the market. Already in the following year a revised successor, the HP-28S, appeared with more memory and higher speed.
The special feature of the HP-28 is its capability to perform not just numerical but also symbolic math. On "large" computers, several algebra systems had been available for some time, such as Mathematica, Maple or Derive, but in calculators this was brand new.
And another novelty: All calculators in the clamshell family were equipped with an infrared port to send results wirelessly to a printer.
Together with the HP-28 a new programming language was introduced, which can still be found today in all powerful pocket computers from Hewlett-Packard: RPL (Reverse Polish Lisp).
Since the limits of the key programming became obvious and Hewlett-Packard didn't really like BASIC either, they invented this new language as a conglomerate of FORTH and LISP. Essential parts of the calculator's operating system were written in RPL, but the language was also available to the user.
Looking back one has to admit that RPL is difficult to learn and the programs are complex to understand. RPL may have held back more users from programming than motivated. Moreover, it is rather slow, which is noticeable especially in lengthy calculations.
Since the limits of the key programming became obvious and Hewlett-Packard didn't really like BASIC either, they invented this new language as a conglomerate of FORTH and LISP. Essential parts of the calculator's operating system were written in RPL, but the language was also available to the user.
Looking back one has to admit that RPL is difficult to learn and the programs are complex to understand. RPL may have held back more users from programming than motivated. Moreover, it is rather slow, which is noticeable especially in lengthy calculations.
The Pioneer family (market launch 1988-91)
The Voyager family was named after a space ship on its way to Saturn (the new processor architecture) and now Pioneer was the name of a spaceship that had already reached Saturn.
My first HP calculator, an HP-32S, dates from this era.
The HP-42S was the most powerful Pioneer (released in 1988) and it is software-compatible with the legendary HP-41.
Although the HP-42 had an infrared port, it otherwise lacked any extension option. The great success of the HP-41 could not be repeated.
The Charlemagne family (market launch 1990-99)
The great desire of the HP-28 development team, to create a calculator with similar expansion options as the HP-41, finally became a reality in March 1990 with the HP-48SX.
More models with similar features appeared in the following years and all had the number 48 in their name.
In August 1999, the HP-49 was introduced. It was the first calculator to work with flash memory and it also visually took off from the earlier 48-series. The internal architecture and operation remained largely the same, however, although the the HP-49 had an improved computer algebra system (CAS).
Flash-ROM memory introduced the ability to update software libraries and the operating system. This technology was so successful that it has been implemented in all high-end calculators since that time.
The HP-49 was the last Hewlett-Packard calculator driven by the now out-dated to 4 MHz Saturn processor.
In 2003, Hewlett-Packard started to modern times with the HP-49g+ (later followed by similar models HP-48gII and HP-50g). On the basis of the ARM architecture (which was clocked over 200 MHz), a much smoother and more comfortable operation was possible compared to the rather phlegmatic predecessors from the HP-48 and HP-49 family. Do not be deceived: except for the coloring and the memory size, the three HP-49g+, HP-48gII and HP-50g calculators are very similar and equipped with almost the same software.
Back to the Roots
One might think that HP considers its old qualities. The HP-35S was introduced just in time for 35th anniversary in 2007. A great calculator in the tradition of the best RPN machines.
Unfortunately the (Chinese) manufacturing quality fails to match earlier successes. I noticed bouncing keys on multiple devices within a short period of usage.
Texas Instruments versus Hewlett-Packard
There is no doubt: Texas Instruments invented the electronic calculator in 1967, and they even got the patent. However, TI's first model (Cal-Tech) was just a prototype that never made it to production. Texas Instrument's first series produced calculator (Datamath) came on the market in 1972 - and had no chance with its four basic operations against the simultaneously released scientific HP-35.
From there on, technical progress was mainly driven by Hewlett-Packard:
Both opponents were at the same time with the introduction of flash memory: In 1999 both the HP-49G and the TI-83 Plus appeared, the former with 2 Mbytes flash memory, the latter with 512 KBytes.
By the end of 2006 or early 2007 the TI-nspire arrived at the market: A programmable graphing calculator with a novel, computer-like operating concept and a large, high resolution display. Mathematical tasks are managed in documents that may contain several pages. These pages contain not only the actual calculation, but also explanatory text, graphics or Excel-like tables. The operating concept is entirely tailored to the requirements of modern mathematics teaching in schools. For engineers or students this is a bit complicated, because you can not calculate "straight on", but you must first create a new document (just as in computers). There is also a computer software for Windows and Macs, that replicates all the functions of the calculator one to one and can be used for teaching purposes.
The CAS (computer aided algebra system) of the TI-nspire was enhanced again and beats it's competitor, the HP-50, significantly in some areas. In addition, the TI-nspire is much more intuitive to use.
Until today (2011) Hewlett-Packard does not offer a similar "math-learning system". If, however, you believe this is (finally) an original invention of Texas Instruments, you are obviously not aware of the Casio ClassPad 300. It was released four years earlier in 2003 and anticipates all "new" features of the TI-nspire - including a replica of the calculator in computer software.
From there on, technical progress was mainly driven by Hewlett-Packard:
- The first pocket calculator with trigonometric and logarithmic functions: HP-35 (1972) versus SR-50 (1974)
- The first programmable calculator: HP-65 (1974) versus SR-52 (1975)
- The first calculator with magnetic card reader: HP-65 (1974) versus SR-52 (1975)
- The first high-performance programmable calculator: HP-67 (1976) vs TI-59 (1977).
- The first calculator with non-volatile memory: HP-25C (1976) versus Ti-58C (1977).
- The first calculator with alphanumeric liquid crystal display: HP41 (1979) versus TI-88 (1982 - never released).
- The first pocket calculator interface for data acquisition: HP-IL (1981) versus TI-CBL (Calculator Based Laboratory) (1994).
- The first calculator that could calculate with complex numbers: HP-15 (1982) versus TI-68 (1988).
- The first pocket calculator in landscape mode with the QWERTY keyboard: HP-71 (1984) versus TI-95 (1986).
- The first pocket calculator with BASIC programming: HP-71 (1984) versus TI-74 Basicalc (1985).
- The first calculator with a computer algebra system (CAS): HP-28 (1987) versus TI-92 (1995).
- The first powerful graphing calculator: HP-48 (1990) versus TI-85 (1992).
- The first calculator based on the new ARM processor architecture: HP-49g + (2003) versus TI-Nspire (2007).
Both opponents were at the same time with the introduction of flash memory: In 1999 both the HP-49G and the TI-83 Plus appeared, the former with 2 Mbytes flash memory, the latter with 512 KBytes.
By the end of 2006 or early 2007 the TI-nspire arrived at the market: A programmable graphing calculator with a novel, computer-like operating concept and a large, high resolution display. Mathematical tasks are managed in documents that may contain several pages. These pages contain not only the actual calculation, but also explanatory text, graphics or Excel-like tables. The operating concept is entirely tailored to the requirements of modern mathematics teaching in schools. For engineers or students this is a bit complicated, because you can not calculate "straight on", but you must first create a new document (just as in computers). There is also a computer software for Windows and Macs, that replicates all the functions of the calculator one to one and can be used for teaching purposes.
The CAS (computer aided algebra system) of the TI-nspire was enhanced again and beats it's competitor, the HP-50, significantly in some areas. In addition, the TI-nspire is much more intuitive to use.
Until today (2011) Hewlett-Packard does not offer a similar "math-learning system". If, however, you believe this is (finally) an original invention of Texas Instruments, you are obviously not aware of the Casio ClassPad 300. It was released four years earlier in 2003 and anticipates all "new" features of the TI-nspire - including a replica of the calculator in computer software.
The next generation - Full-Color Backlit Displays
It seems Casio has taken over Hewlett-Packard's previous role as the pocket calculator innovator: The FX-CG20 (FX-CG10 in the U.S.) has a full-color backlit display just like a smartphone. It was introduced in autumn 2010 and is available since beginning of 2011.
Texas Instruments didn't take long to copy this idea: Already in spring of 2011 the TI-nspire CX was introduced: With a full-color backlit display! It will be available starting early summer 2011.
Texas Instruments didn't take long to copy this idea: Already in spring of 2011 the TI-nspire CX was introduced: With a full-color backlit display! It will be available starting early summer 2011.
Left: This is the future of pocket calculators according to Casio in late 2010: curve sketching of real objects.
Right: An image of the new TI-nspire CX - half a year later than the image to the left.
Any similarities are purely coincidental, of course ...
Right: An image of the new TI-nspire CX - half a year later than the image to the left.
Any similarities are purely coincidental, of course ...
Current situation (2011/12)
Unfortunately it seems Hewlett Packard has given up competition to its former rival Texas Instruments.
For the most part the HP-50g is based on the already 20 year old concept of the HP-48 SX. It can not hold up against the modern TI-nspire CX and its backlight color display.
What else was there ?
The HP-95LX is a full-fledged MS-DOS PC from 1991 with a 8088 compatible processor which is clocked at 5.37 MHz. Memory expansion to 512 KBytes or 1 MByte is available, and MS-DOS 3.3 and Lotus 1-2-3 is fixed in ROM.
The Apple Newton was published under the name MessagePad 100 for the first time in 1994. Similar to the later HP calculators and today's iPhone's processor architecture, it is based on the ARM chip. The photo shows the improved MessagePad 130 of 1997.
Links
The Museum of HP Calculators A wonderful treasure trove of all historical Hewlett-Packard calculators - starting with the first table calculating machines.
VCALC.net Tons of info about early calculators from a crazy collector.
hpcc.org The hp Computer Club has existed for over 20 years.
HP Virtual Museum Also Hewlett-Packard maintains a virtual Web Museum.
hpcalc.org Information and programs for all RPL calculators from the HP-28 up to the recent HP-50.
Datamath A website with pictures and information about early Texas Instruments calculators.
ticalc.org Information and programs for TI graphing calculators.
TI-Basic Developer BASIC programming for the latest TI graphing calculators.
Vier technisch-wissenschaftliche Taschenrechner im Vergleich My article from the computer magazine c't 12/1990 (in German language).
Emulators
A free HP-12C dashboard widget für Mac OS X.
The original HP-15C emulator for iOS (pricey but very good).
Another good emulator for iOS is this HP-42s.
This is the famous HP41CX as iOS emulation.
A genuine RPN calculator for iOS without any well-known archetype.
Free42 is an Open Source project available for many pc- and mobile phone platforms.
This TI58C/59 emulator is android only.