The FX-501P and FX-502P were

programmable calculator Programmable calculators are calculators that can automatically carry out a sequence of operations under the control of a stored computer programming, program. Most are Turing complete, and, as such, are theoretically general-purpose computers. ...

s, manufactured by

Casio is a Japanese multinational electronics manufacturing corporation headquartered in Shibuya, Tokyo, Japan. Its products include calculators, mobile phones, digital cameras, electronic musical instruments, and analogue and digital watches. It ...

from 1978/1979. They were the predecessors of the FX-601P and FX-602P. It is likely that the FX-501P/502P were the first LCD programmable calculators to be produced as up until 1979 (and the introduction of the HP-41C) no manufacturer had introduced such a device.

Arithmetic

The FX-502P series use

algebraic logic In mathematical logic, algebraic logic is the reasoning obtained by manipulating equations with Free variables and bound variables, free variables. What is now usually called classical algebraic logic focuses on the identification and algebraic de ...

as was state-of-the-art at the time.

Display

The FX-501P and FX-502P featured a single line 7-segment liquid crystal display with 10 digits as main display. An additional 3 digits 7-segment display used to display exponents and program steps when entering or debugging programs and 10 status indicators. The display was covered with a yellow filter, They were the first Casio calculators to implement

engineering notation Engineering notation or engineering form (also technical notation) is a version of scientific notation in which the exponent of ten is always selected to be divisible by three to match the common metric prefixes, i.e. scientific notation that al ...

, and the first calculators in general to implement an engineering notation with shift facility (following

Hewlett Packard The Hewlett-Packard Company, commonly shortened to Hewlett-Packard ( ) or HP, was an American multinational information technology company. It was founded by Bill Hewlett and David Packard in 1939 in a one-car garage in Palo Alto, Californi ...

calculators implementing the first

in general, and some

Commodore Commodore may refer to: Ranks * Commodore (rank), a naval rank ** Commodore (Royal Navy), in the United Kingdom ** Commodore (India), in India ** Commodore (United States) ** Commodore (Canada) ** Commodore (Finland) ** Commodore (Germany) or ' ...

and

Texas Instruments Texas Instruments Incorporated (TI) is an American multinational semiconductor company headquartered in Dallas, Texas. It is one of the top 10 semiconductor companies worldwide based on sales volume. The company's focus is on developing analog ...

calculators implementing

variable scientific notation Engineering notation or engineering form (also technical notation) is a version of scientific notation in which the exponent of ten is always selected to be divisible by three to match the common metric prefixes, i.e. scientific notation that al ...

with exponent shift facility).

Programming

The programming model employed was key stroke programming by which each key pressed was recorded and later played back. On record multiple key presses were merged into a single programming step. All operations fitted into one program step. The FX-501P could store 128 steps, with 11 memory registers. The FX-502P had twice that capacity with 256 steps and 22 memory registers. Conditional and unconditional jumps as well as subroutines were supported. The FX-502P series supported 10 labels for programs and subroutines called P0 .. P9. Each program or subroutine could have up to 10 local labels called LBL0 .. LBL9 for jumps and branches. The FX-501P and FX-502P supported indirect addressing both for memory access and jumps and therefore the programming model could be considered

Turing complete Alan Mathison Turing (; 23 June 1912 – 7 June 1954) was an English mathematician, computer scientist, logician, cryptanalyst, philosopher and theoretical biologist. He was highly influential in the development of theoretical comput ...

. Since the FX-501P and FX-502P only employed a

seven-segment display A seven-segment display is a display device for Arabic numerals, less complex than a device that can show more characters such as dot matrix displays. Seven-segment displays are widely used in digital clocks, electronic meters, basic calculators, ...

each program step was represented by a special 2-digit codes made up of the digits 0 .. 9 and the character C, E, F and P. The calculator came with a special overlaycasio fx-501p with programming overlay
/ref> so the user did not need to memorize the mapping between code and actual command. What differentiated the FX-501 / FX-502P from its competitors was that programming was retained in a battery-buffered memory when the calculator was turned off.

Programming example

Here is a sample program that computes the factorial of an integer number from 2 to 69. For 5!, the user would type 5 P0 and get the result 120. The whole program is only 9 bytes long.

Interface

The FX-501P and FX-502P used the FA-1 to store program and data to

Compact Cassette The Compact Cassette, also commonly called a cassette tape, audio cassette, or simply tape or cassette, is an analog magnetic tape recording format for audio recording and playback. Invented by Lou Ottens and his team at the Dutch company ...

using the Kansas City standard. The FA-1 also enabled the calculators to generate musical notes. The FX-501P was used on the 1981 song "Pocket Calculator" by electronic music group

Kraftwerk Kraftwerk (, ) is a Germany, German Electronic music, electronic band formed in Düsseldorf in 1970 by Ralf Hütter and Florian Schneider. Widely considered innovators and pioneers of electronic music, Kraftwerk was among the first successful a ...

Arithmetic

Display

Programming

Programming example

Interface

References

External links