The Casio

Casio

is a multinational electronic devices manufacturing company founded in 1946, with its headquarters in Shibuya, Tokyo, Japan. Casio is best known for its electronic products, such as calculators, audio equipment, PDAs, cameras, musical instruments, and watches...

 FX-850P is a scientific calculator

Calculator

An electronic calculator is a small, portable, usually inexpensive electronic device used to perform the basic operations of arithmetic. Modern calculators are more portable than most computers, though most PDAs are comparable in size to handheld calculators.The first solid-state electronic...

 introduced in 1987 and sold until 1992.

Specifications

• 2 lines with 32 5×7 characters LCD
  Liquid crystal display
  A liquid crystal display is a flat panel display, electronic visual display, or video display that uses the light modulating properties of liquid crystals . LCs do not emit light directly....
  
  
  • (some indicators and a 5 digit 7-segment display)
• 8 KB RAM (FX-860P: 24 KB, FX-880P: 32 KB)
• CPU: VLSI at 1,228MHz. Hitachi HD62002A01 (FX-860P, FX880P: HD62002A03)
• Integrated speaker
• Internal slot for memory expansion (32 KB)
• Connector with support for RS232 and Centronics (only level converter for RS232, Centronics needed)
• LCD Driver: 2 x HD66100F
• 2x 3V CR2032 lithium batteries as main power supply
  Power supply
  A power supply is a device that supplies electrical energy to one or more electric loads. The term is most commonly applied to devices that convert one form of electrical energy to another, though it may also refer to devices that convert another form of energy to electrical energy...
  
  
• 1x 3V CR1220 lithium battery as memory backup (RAM power supply)

User's manual at http://www.usersmanualguide.com/casio/calculators/fx-850p

The calculator had a BASIC interpreter, MEMO function, a formula library. The built-in 8 kB memory could be expanded using the optional Casio RP-8 (8 kB) or RP-33 (32 kB) RAM expansion modules. An optional Casio FA-6 interface board provided a cassette tape recorder connector, a Centronics

Centronics

Centronics Data Computer Corporation was a pioneering American manufacturer of computer printers, now remembered primarily for the parallel interface that bears its name.-The beginning:Centronics began as a division of Wang Laboratories...

 printer connector and an RS-232C port. The calculator could print data and listings on any Centronics printer; printing graphics required the Casio FP-100 plotter-printer.

Later, Casio released the FX-880P, which had 32 kB built-in memory. With a RP-33 expansion module, this model could be upgraded to a total of 64 kB.

The memory layout is:

• 0000-00FF Screen memory
• 0100-01FF Reserved for internal functions
• 0200-02ff INPUT Buffer
• 0300-03FF CALCJMP, VALF Buffer
• 0400-04FF Reserved for IN/OUT/CALC modes (CALC$)
• 0500-074A Reserved for internal functions
• 074B-0752 Reserved for storing the user PASSWORD
• 0753-175A Reserved for internal functions
• 175B-175C Vector pointing to MEMO memory start
• 175D-1FE4 Reserved for internal functions
• 1FE5-1FFF Vectors pointing to P0-P9 memory start
• 2000-9FFF User memory (shared by MEMO and P0-p))
• A000-BFFF Repetition of 0000-1FFF
• C000-DFFF Repetition of 0000-1FFF
• E000-FFFF Repetition of 0000-1FFF

Memory area A000-FFFF was either available as user memory (if expansion was present), or would simply repeat the contents of 0000-1FFF

A few glitches are:

• POKE 1867,0 → would delete any user PASSWORD
• POKE PEEK(8027)+256*PEEK(8028),32 → would recover contents of MEMO after a RESET ALL
• POKE PEEK(8027)+256*PEEK(8028),26 → would hide contents of MEMO, much like a RESET ALL would do, but without losing the programs

The internal function library was programmed in BASIC itself and could be extracted with a BASIC decompiler.

Any function in the library can be executed from a regular BASIC program by using GOTO "LIB0:NNNN" where NNNN is the function number (e.g. 5010 for prime factorization). The command GOTO "LIB0:0400" executes a self-test program.

Characters 252 to 255 were user defined. They could be defined by issuing the command DEF CHR$(n)="HHHHHHHHHH" where n ranges from 252 to 255 and the H's are 10 hexadecimal digits (5 bytes). Every byte defines the pixel pattern for a column. Since a column is 7 pixels high, the least significant bit of every byte is ignored.

The CHR$(26) would activate a different character set for Katakana

Katakana

is a Japanese syllabary, one component of the Japanese writing system along with hiragana, kanji, and in some cases the Latin alphabet . The word katakana means "fragmentary kana", as the katakana scripts are derived from components of more complex kanji. Each kana represents one mora...

 and Kanji

Kanji

Kanji are the adopted logographic Chinese characters hanzi that are used in the modern Japanese writing system along with hiragana , katakana , Indo Arabic numerals, and the occasional use of the Latin alphabet...

 characters. CHR$(27) would deactivate Kanji.

Via a serial cable the calculator could connect to a PC

Personal computer

A personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end-user with no intervening computer operator...

or to another Casio FX-850P, allowing the transfer to MEMO and stored programs.

External links

• Casio FX-850P on MyCalcDB Database of 1970s and 1980s pocket calculators