The FX-501P and FX-502P were

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

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. I ...

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 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,

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. Turing was highly influential in the development of theoretical co ...

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

seven-segment display A seven-segment display is a form of electronic display device for displaying decimal numerals that is an alternative to the more complex dot matrix displays. Seven-segment displays are widely used in digital clocks, electronic meters, basic ...

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 using the

Kansas City standard The Kansas City standard (KCS), or ''Byte'' standard, is a data storage protocol for standard cassette tapes at . It originated in a symposium sponsored by ''Byte'' magazine in November 1975 in Kansas City, Missouri to develop a standard for th ...

. 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.

Arithmetic

Display

Programming

Programming example

Interface

References

External links