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CASIO FX-702P

Date of introduction:  November 1981 Display technology:  LCD
New price:  $249.00 (MSRP 1981) Display size:  20 Alpha + 2 Numeric
Size:  3.2" x 6.5" x 0.70"
 82 x 165 x 18 mm3
   
Weight:  6.3ounces, 179 grams Serial No:  1B209A
Batteries:  2*CR2032 Date of manufacture:  mth 01 year 1982
AC-Adapter:   Origin of manufacture:  Japan
Precision:  12 Integrated circuits:  CPU: HD43190A02, HD43190A03
 RAM: 4*uPD444G
 DISP.: HD43191A02, HD43191A03
Memories:  26-226    
Program steps:  1.680-80 Courtesy of:  Joerg Woerner

Sharp Corporation introduced in June 1980 with the PC-1210 (and its sibling PC-1211) the World's first Pocket Computer with BASIC programmability. It took only about three months and Matsushita defined with their Panasonic HHC a new category of Hand-held Computers or Portable Computers. Main competitor in Japan, Casio Computer Co., Ltd, on the other hand introduced with the FX-501P and FX-502P in October 1979 their first keystroke Programmable Pocket Calculator with LC-Display, succeeded in March 1981 with the FX-601P and FX-602P, introducing a dot matrix LC-Display and laying the foundation for the FX-702P "Pocket Computer". Casio took a different approach than Sharp and added BASIC programmability to a Scientific Calculator and labeled the device with "Programmable Calculator" accordingly. Casio's early advertisement featuring the FX-702P used often a big headline "More Power To Your Pocket" to challenge rival Sharp.

With the three cornerstones of the emerging market defined, Sharp consequently split their portfolio for the successors of the PC-1201/PC-1211 into two different directions:

PC-1500 (1982): Portable Computer as a center of a
   Computer System with many peripherals
PC-1401 (1983): Hybrid of a Pocket Computer with BASIC
   Programmability and a Scientific Calculator

The FX-702P Programmable Calculators features not only an internal expansion slot for a memory cartridge but a 7-pin connector for peripherals on its left side:

Product Description MSRP (1981)
FA-2 Cassette Interface
(Fits FX-501P/FX-502P/FX-601P/FX-602P, too)
$49.00
FP-10 Mini Printer, electro-sensitive FP-36 paper, up to 20 characters per line, 2 lines per second
(Fits FX-601P/FX-602P, too)
$109.00
(not released) 4k Bytes RAM module with backup battery  
(not released) 8k Bytes RAM module with backup battery  

Dismantling the featured Casio FX-702P manufactured in January 1982 by Casio Computers in Japan reveals a complex design based on two printed circuit boards (PCBs) in a clamshell packaging. The larger of the two PCBs is populated with two 4-bit microcontrollers and two Integrated Circuits (ICs) to drive the alphanumeric LC-Display. The smaller of the two PCBs holds four RAM (Random-access Memory) chips.

The two PCBs of the FX-702P Pocket Computer hold an impressive list of ICs and Casio proved again the leadership of Japanese companies in miniaturization:

HD43190A02: 4-bit microcontroller with integrated RAM and ROM and display driver for 8 rows manufactured
   by Hitachi in a CMOS process and using an 80-pin QFP (Quad Flat Pack) package
HD43190A03: 4-bit microcontroller with integrated RAM and ROM manufactured by Hitachi in a CMOS process and using
   an 80-pin QFP (Quad Flat Pack) package
4*PD444G: 512*4 Bits RAM manufactured by NEC in a CMOS process and using a 52-pin QFP (Quad Flat Pack) package
HD43191A02: Display driver for 54 columns with built in RAM, manufactured by Hitachi in a CMOS process and using
   an 80-pin QFP (Quad Flat Pack) package
HD43191A03: Display driver for 54 columns with built in RAM, manufactured by Hitachi in a CMOS process and using
   an 80-pin QFP (Quad Flat Pack) package

Comparing the ICs of a FX-702P BASIC Programmable Calculator with the chips of a FX-602P keystroke Programmable Calculators unveils an unexpected similarity:

FX-602P: HD43190A01, HD43191A01, 1*uPD444G
FX-702P: HD43190A02, D43190A03, HD43191A02, HD43191A03, 4*uPD444G



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If you have additions to the above article please email: joerg@datamath.org.

Joerg Woerner, January 5, 2021. No reprints without written permission.