Programmable calculator
Programmable pocket calculators are pocket calculators that, like computers , can be programmed to process complex arithmetic operations.
Development history
Particular milestones in the development of programmable pocket calculators (some features were first introduced in non-programmable models) were:
- 1974 was developed by Hewlett-Packard of (HP) HP-65 introduced the world's first programmable calculator. Since the program and data memory was deleted when it was switched off, the pocket calculator also received a magnetic card reader for external storage of the programs. It was also essential for the dissemination that the owners of identical pocket calculators could exchange software using magnetic cards.
- The programming consisted in the fact that the manual calculation sequence was saved as keystrokes for repeatable execution and could be enriched with control structures (comparisons, loops, jumps) and memory operations. A special feature of the HP models was the input logic , which was called Reverse Polish Notation (UPN) and which was considered advantageous in implementation.
- In 1975 the SR-52 from Texas Instruments (TI) mastered the indirect addressing of data registers and program lines. In addition, the SR-52 could be connected to a special thermal printer (PC-100A from TI) and output data such as programs on thermal paper.
- In contrast to HP, TI favored the AOS ( Algebraic Operation System ) as the input logic with the usual operator priority such as point calculation before line calculation .
- In 1975 the HP-55 appeared with a quartz oscillator that enabled stopwatch functions.
- In 1975 , the HP-65 came into orbit (approx. 187–222 km altitude) as part of the Apollo Soyuz test project .
- In 1976 , with the HP-25C, the RAM was implemented using energy-saving CMOS technology, so programs and data were retained even after switching off ("Continuous Memory").
- In 1976 , the HP-67 and HP-97 replaced the HP-65 as pocket calculators (HP-67) and fully compatible desktop calculators with printer (HP-97). It was now possible to process programs that were larger than the memory of the computer. To do this, the “Merge” command requested a new magnetic card that overwritten the existing program parts.
- In 1977 the TI-59 was presented as the successor to the SR-52, which was prepared for small changeable ROM modules with software ("Solid State Software", approx. 5 kB / module) on various topics (statistics, navigation). The TI-59 was able to divide its (for the time) huge RAM of 960 bytes variably between data memory and program memory.
- In 1977 the HP-19C was also introduced, which integrated the printer in its compact pocket calculator housing.
- In 1977 the HP-97S was presented, an extended HP-97, which was first equipped with an external interface ( BCD , parallel).
- In 1978 , with the HP-38E , a mathematical financial calculator was first programmable. Until now, the manufacturers of programmable pocket calculators had concentrated on technical and scientific areas of application.
- In 1979 the HP-41C received an alphanumeric LC display (Texas Instruments had introduced an LCD with purely numerical representation in the non-programmable TI-1750 as early as 1977), could display texts and process them in the program. Optional connections and modules for the bays of the HP-41C have been added to the range over the years, e.g. B. RAM, time functions, special functions, card readers, printers, barcode readers, infrared module for other printers. For the first time, the memory areas for different programs were sealed off from one another. In the course of its further 10-year construction period, an interface loop was offered with which, for example, magnetic cassette devices or measuring devices could be controlled or read.
- In 1979 the Sharp EL-5100 appeared. It had a dot matrix display to show numbers and characters (as opposed to the alphanumeric segment display of the HP-41C ). The EL-5100 could only be programmed with a formula without jump commands or conditional instructions.
- In 1981 the financial mathematical HP-12C was presented, which has been built almost unchanged since then (as of 2017) and should therefore be the longest-selling programmable pocket calculator on the market.
- In 1981 NASA began giving HP-41 models to the astronauts on the Columbia space shuttle . The astronauts were able to use special HP-41 programs to check the parameters for re-entry that the on-board computer had calculated. In 1985 , an HP-41CX took part in the German D1 mission in the space shuttle; the device from the D1 mission is now in the possession of the Deutsches Museum .
- In 1982 , with the HP-75C, the motor for magnetic card readers, which was too energy-hungry for battery operation, was abolished again. The magnetic cards were drawn by hand through a slot on the housing.
- In 1982 , with the HP-16C, a calculator was introduced especially for programmers, for example to calculate in different number systems. Texas Instruments had already released the TI Programmer in 1977 , but it was not programmable.
- In 1982 , the HP-15C was introduced, a calculator that offered a stack for complex numbers and thus could easily handle many electrical engineering calculations (TI had already introduced the non-programmable TI-54 for real and complex "algebraic functions" in 1981). Matrix operations and functions have also been implemented as a built-in function of the HP-15C. Since the HP-15C could neither print nor transfer programs externally, the exchange of software was limited. In 2011, Hewlett Packard launched a 'Limited Edition' of this computer, which, as a replica of the original HP-15, was visually very similar, but worked around 100 times faster.
- In 1984 the Sharp EL-5400 appeared for the first time as a pocket calculator with BASIC as the high-level programming language. In terms of design and programmability, the EL5400 was based on the Sharp PC-1210 introduced in 1979, the first BASIC-programmable pocket computer.
- In 1985 Casio introduced the FX-7000G, the first calculator with graphics capability . The various graphic functions could be called up manually as well as used in self-written programs.
- In 1986 Casio's fx-5500 appeared , the first pocket calculator with a limited computer algebra system (CAS). The fx-5500 was able to manipulate expressions symbolically (factorize, expand, simplify). The calculator could only be programmed with formulas without jump commands or conditional instructions.
- In 1987 the HP-28C was introduced. The HP-28 used a new, HP-own language ( RPL ), which enabled recursive programming, calculated unrestricted with real and complex numbers, allowed matrix algebra and graphic representations and could calculate and derive symbolic expressions. All memories (variables, subroutine return levels, stack levels) were only limited by the capacity of the RAM, so that programs could call any other programs without any reaction. The development culminated in the HP-48SX and its successors.
- In 1990 the HP-48SX received an RS-232 interface as standard, with which data and programs could be saved on PCs. An infrared interface made it possible to exchange data and programs with compatible models.
- 1995 appeared with the TI-92 the first pocket calculator with a complete computer algebra system (based on Derive ). The TI-92 is programmable in a BASIC-like language.
In the early days, programmable pocket calculators competed with slide rules and simple pocket calculators, so that the high-quality calculators were particularly popular with scientists and engineers and were programmed for numerous technical and (to a limited extent) business issues. When LC displays became inexpensive at the end of the 1980s and more and more graphical pocket calculators came onto the market, competition from spreadsheets on PCs grew at the same time , which ultimately led to the spread and thus the development and sale of new generations of programmable pocket calculators braked. Significant new developments in this area are therefore no longer to be expected.
technology
Programmable pocket calculators have an internal memory in which programs can be stored that can simplify or automate complex calculation processes. Such programs are entered using the calculator's keyboard in a special program entry mode. Due to the mostly simple displays in pocket calculators (previously only one line to display numbers, today mostly several lines), the editing of programs is limited to scrolling commands (one program command forward, one program command back in the display), inserting, overwriting and deleting Command. Early calculators did not allow letters to be entered, so only key commands on the keyboard could be used. The programming was close to the machine, i.e. H. Storage registers and program registers were used explicitly ("Store 5 in storage register 3": 5 STO 3 in UPN; "Jump to program line 78": GTO 78 etc.). Programmable pocket calculators, which are also capable of graphics, meanwhile often already offer text editors with sometimes quite extensive functionality for these purposes (and often do not have a special programming mode).
The main disadvantage of programming key sequences was that common resources such as data memory, arithmetic registers / stack and flags could not be sealed off. With a third-party utility program, it was not enough to know the input and output (as with the built-in functions of the pocket calculator), but you also had to check the allocation of resources and conflicts with your own program. Necessary changes were only possible manually and, in the case of programs that worked with indirect addressing of memory registers, only possible after analyzing the program. Only programming languages such as RPL at HP (introduced with the HP-28C and the HP-48/49 / ... ff. Models) allowed more extensive program collections without the execution of external auxiliary programs and subroutines having disrupted the own program.
Programs could initially only be saved in the pocket calculator itself, later also on magnetic cards . Few models allowed the reading of programs via barcodes and magnetic tape drives (HP-41). With the market success of the PC, modern pocket calculators were also able to communicate with computers from the 1990s onwards. From then on, it was possible to design ready-made programs for the pocket calculator on the PC or to load them from the Internet (from the mid-1990s) and then transfer them to the pocket calculator using a special transmission cable (now USB).
application
The range of possible programs is very large. From math programs and geometry programs to games , almost every genre of programs is represented. It has been shown that the functional orientation of the computers was predominantly scientific. Calculators specializing in financial mathematics came out late. Due to the still limited graphics options and the moderate working speed, games are rather simple and have only found little use.
Exchange of software
The calculators were only programmable in their own proprietary way, and programs could only be exchanged using magnetic cards until the mid-1980s . In the case of computers, this mostly included downward compatibility with the previous model, otherwise users were dependent on printed media to exchange software. For the HP-41C, HP developed a barcode reader that could easily accept printed barcodes. However, users had no official way to create barcodes themselves until hobbyists presented a conversion of the HP printer to the 41C. HP later introduced the Interface Loop , which for the first time allowed floppy disks and magnetic cassettes to be used to store data and programs, albeit at a comparatively high price.
The manufacturers of high-quality computer software for their products have been distributed with topic-oriented solution books. HP sold the packages with magnetic cards, later with barcodes for the HP-41C, while Texas Instruments even offered ROM modules for the TI-59, for example for navigation at sea.
With its Users Program Library Europe (UPLE) and a reward system for submitted software, Hewlett-Packard contributed to the free exchange of programs between users until 1983.
The distribution of software was also promoted by specialist magazines and, above all, by various associations:
- Computerclub Deutschland eV (CCD), which was founded in November 1981. The membership magazine was called PRISMA, and in addition to program listings, the HP-41 was later also printed as barcodes.
- Micro-Pocket Computer User Club (MICAC, formerly German Chapter of the HP-65 Users Club) in Cologne, the members' magazine was called 'Display'.
- TI 58-59 Software Club
nostalgia
There are now a number of emulators and simulators for various operating systems, most of which emulate old Hewlett-Packard pocket calculators and sometimes use the original code. These replicas can also be programmed in the same way as the original computers. Especially with HP computers this means that essential features such as UPN or BCD arithmetic (instead of binary arithmetic) have been retained.
The highlight so far is the replica of various computers, most of which come from the Voyager series from HP. HP itself announced a limited edition of the HP-15C in 2011 and released it later. The provider Swiss Micros has released most of the Voyager series computers and other models as replicas with the original HP microcode since 2012, with the original HP processor being emulated by a current microprocessor. HP also used this method for the Limited Edition.
Individual evidence
- ↑ See SR-52 Owners Manual (PDF; 27.4 MB) from 1975, p. 115 ff., Accessed on January 5, 2011
- ↑ Picture and description on Mr. Martin's website , accessed January 5, 2012
- ↑ HP calculators and space exploration , accessed January 5, 2012
- ↑ HP Key Notes Vol. 5 N1 (Jan. 1981; PDF; 3.0 MB), accessed on January 5, 2012, HP customer magazine
- ↑ Details on the HP-75 , accessed on January 5, 2012
- ↑ http://www.hpmuseum.org/forum/thread-7748.html
- ↑ See HP Key Notes Vol. 6 No. 2 from March-May 1982, ISSN 0730-2037
