DATAMATH

DATAMATH CALCULATOR MUSEUM

Datexx DC-80

Date of introduction:	2008	Display technology:	LCD
New price:	MSRP $15.00 (2010)	Display size:	8
Size:	2.1" x 3.3" x 0.30" 54 x 85 x 7 mm³
Weight:	1.0 ounces, 26 grams	Serial No:
Batteries:	LR54	Date of manufacture:	year 2011
AC-Adapter:		Origin of manufacture:	China
Precision:	8	Integrated circuits:	ELAN ePS6500
Memories:	1+100
Program steps:		Courtesy of:	Joerg Woerner
		Download manual:	(US: 0.8 MByte)

National Semiconductor introduced already in 1978 with the NS103 Data Checker an electronic record keeper with three continuous memories to track bank and charge account balances with dedicated keys:

• Memory 1 [CHK] [DEP] [BAL] [A]
• Memory 2 [PMT] [CHG] [BAL] [B]
• Memory 3 [PMT] [CHG] [BAL] [C]
• Total sum of Memories [GT]

While the NS103 Data Checker was based on proprietary technology, introduced NEC of Japan with the uPD1833G in 1980 a single-chip calculator circuit that created the blueprint for checkbook-sized Account Manager calculators and thereupon the market got swamped with products based on this design. The uPD1833G simplified the use of the memories by removing the redundant [A], [B], and [C] keys and replaced the inconvenient three-way power-switch of the NS103 Data Checker with two dedicated [ON] and [OFF] keys and a [DS] key to toggle between two entry modes:

• Indicator (--) Floating decimal with manual insertion of the decimal using the [.] key
• Indicator (AM) Add mode with the decimal automatically put in the dollars and cents position (0.00)

Even the successor of the NS103, known as NS103A, switched its internals to the uPD1833G but we feature some more Account Manager calculators in the Datamath Calculator Museum based on this technology:

• Canon Checkbook - Missing the Toggle Key for the decimal mode
• Royal LCB 841 - The Art of Perfection in Japan
• Royal LCB 835 - Just one Memory (uPD1831G)
• Texas Instruments TI-2200 Checkwriter - Late, but not too late
• Unisonic LC 262CK Check Master - Credit Card sized

NEC of Japan lost some market share with their design for Account Manager calculators in the Eighties, when competitors like Hitachi and Sharp introduced similar chips and finally lost the business completely to Toshiba's "Solar Cells" compatible design. Find more Account Manager calculators in the Datamath Calculator Museum:

• Canon Checkbook II - Toshiba inside
• Casio CB-80 - Hitachi inside
• Unisonic LC 224CK Check Master - Sharp Inside
• Texas Instruments TI-2200 II Checkwriter - Toshiba + Solar cells = Winning formula

Dismantling the featured Datexx DC-80 Credit Card Balance Tracker manufactured in 2011 by Karce in China reveals a clean design centered around an ELAN ePS6500 single-chip calculator circuit mounted in Chip-On-Board (COB) technology directly on the printed circuit board and hiding under a small epoxy blob. The electronics is powered by a small LR54 (LR1130) battery.

Inspecting the PCB of this DC-80 manufactured in 2011 brought our attention to a small mark reading KC-129AP AA04, obviously a reference to its OEM manufacturer Karce and Revision AA04 of the design (schematics and layout).

Please find an overview of the PCB-Marks we discovered so far on Account Manager calculators.

Learn more about single-chip calculator circuits used in Account Manager Calculators.

Don't miss the Corvus CheckMaster introduced by Mostek already in 1975. This rare product retains the balance of your memory even when shut off but uses power-hungry electronics.

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