Casio FX-850P

• Name — Casio FX-850P • Type — Pocket Computer • Entry — Infix, BASIC • Manufacturer — Casio • Display Type — LCD Dot-matrix • Display Size — 2×32 Character • Prog Lang — BASIC • Processor — Hitachi HD62002A01 • Speed — 1,228MHz • Conn1 — Compact Cassette • Via1 1 — FA-6 • Conn2 — Line Printer • Via2 1 — FA-6 • Via2 2 — Centronics printer port • Conn3 — PC • Via3 1 — FA-6 • Via3 2 — RS-232 • Ports — one vendor specific • Supply — 2×"CR2032" Lithium + 1×"CR1220" Lithium • Weight — 197 g

• 2 lines with 32 5×7 characters LCD • (some indicators and a 5 digit 7-segment display) • 8 KB RAM (FX-860P: 24 KB, FX-880P: 32 KB) • CPU: VLSI at 1.228 MHz. 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 • 1x 3V CR1220 lithium battery as memory backup (RAM power supply) User's manual at http: www.usersmanualguide.com/casio/calculators/fx-850p The computer 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 printer connector and an RS-232C port. The computer 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$) • 0500-074A Reserved for internal functions • 074B-0752 Reserved for storing the user PASSWORD • 0753-175A Reserved for internal functions • 175B-175C Vector pointing to MEMO memory start • 175D-1FE4 Reserved for internal functions • 1FE5-1FFF Vectors pointing to P0-P9 memory start • 2000-9FFF User memory (shared by MEMO and P0-P9) • A000-BFFF Repetition of 0000-1FFF • C000-DFFF Repetition of 0000-1FFF • E000-FFFF Repetition of 0000-1FFF Memory area A000-FFFF was either available as user memory (if expansion was present), or would simply repeat the contents of 0000-1FFF A few glitches are: • POKE 1867,0 → would delete any user PASSWORD • POKE PEEK(8027)+256*PEEK(8028),32 → would recover contents of MEMO after a RESET ALL • POKE PEEK(8027)+256*PEEK(8028),26 → would hide contents of MEMO, much like a RESET ALL would do, but without losing the programs The internal function library was programmed in BASIC itself and could be extracted with a BASIC decompiler. Any function in the library can be executed from a regular BASIC program by using GOTO "LIB0:NNNN" where NNNN is the function number (e.g. 5010 for prime factorization). The command GOTO "LIB0:0400" executes a self-test program. Characters 252 to 255 were user defined. They could be defined by issuing the command DEF CHR$(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$(26) would activate a different character set for Katakana and Kanji characters. CHR$(27) would deactivate Kanji. Via a serial cable the calculator could connect to a PC or to another Casio FX-850P, allowing the transfer to MEMO and stored programs.