Sanyo ICC-804D

Sanyo Electronics Company (Japan) entered the market of portable, electronic calculators already in May 1970 with the ICC-82D (Integrated Circuit Calculator). The unusual combination of Nixie tubes and a rechargeable battery for a portable calculator was only a temporary solution. The second design of the ICC-82D was introduced in January 1971 together with the ICC-0081 and used amber colored gas-discharge tubes with the common seven-segment layout.

Within a few months engineers at Sanyo managed it to squeeze the four chip design of the ICC-82D into a package barely larger than the later Texas Instruments Datamath and introduced this incredible ICC-804D, a.k.a. Dictaphone 1681.

Key component of the ICC-804D was the latest display technology, the 8-digit Light-Emitting-Diode (LED) display is much smaller than the gas-discharge display or even the Nixie tubes found in the ICC-82D. Nevertheless lost Sanyo the race for the first electronic calculator with LED display, the legendary Busicom LE-120S was available around June 1971, while the earliest ICC-804D were delivered around August or September to the customers.

Within another few months Bowmar introduced its model 901B based on Texas Instruments’ "calculator-on-a-chip" technology and the Calculator War was waiting already around the corner!

Dismantling the featured Sanyo ICC-804D manufactured in September 1971 in Japan reveals a miracle of engineering! Even today, almost 40 years after its introduction, you ask yourself: Why did they combine such an old-fashioned technology like magnetic reed switches and a four-chip calculator brain with the latest LED technology, yielding to an almost unaffordable product with a list price of ¥ 79,500? 

The ICC-804D is not only a heavy calculator, its specific density is much higher than usual. The calculator feels extremely solid and no space inside is left unused. Removing the backside shelf of the calculator housing with its integrated rechargeable NiCd cells attached to it, gives access to a metal frame with multiple printed circuit board (PCB) assemblies:

The main PCB forms together with the display PCB an extremely compact assembly based on the well-known four integrated circuits with SANYO LM8001, LM8002, LM8003, and LM8005 markings. These chips were manufactured under license of General Instruments Corp., together with Rockwell and Texas Instruments one of the pioneers in the development of LSI circuits (Large-Scale-Integration) in MOS technology. 

The display PCB is attached with a robust connector to the main PCB and sports a total of 8 seven-segment LED modules and 3 discrete LED indicators. We couldn’t locate any markings on the LED modules, but assume that they were manufactured by Monsanto.

The keyboard assembly consists of a PCB with 18 reed switches soldered onto a PCB and their corresponding keys with small magnets attached and a small coil spring. Both the [ON/OFF] and [0/2/4] switch are wired to the keyboard PCB, which uses a huge connector to the main PCB.

The internal construction of the ICC-804D was slightly changed in December 1971. Fellow collector Peter Muckermann reported recently his ICC-804D with serial number C7066953 sporting a much simpler keyboard assembly without the reed switches and a SANYO LM8006 chip instead the LM8005 found in the original design.

This early Sanyo ICC-804D was donated by Lowell Yunker. Thanks!

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

© Joerg Woerner, January 7, 2010. No reprints without written permission.