National Semiconductor NS103 Data Checker

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

The NS103 Data Checker makes use of a three-way power switch selecting either floating decimal with manual insertion of the decimal using the [.] key or add mode with the decimal automatically put in the dollars and cents position (0.00).

Dismantling the featured NS103 Data Checker manufactured in January 1979 in Taiwan reveals a clean design centered around a Mitsubishi M58490P single-chip calculator soldered on a single-sided printed circuit board (PCB) circuit powered by just two LR44 batteries.

Please notice the changes of the Brand Identity of the Data Checker product line over time.
Inspecting the PCB of this NS103 manufactured in January 1979 brought our attention to a small mark reading NS103, obviously a reference to the product name and original Revision of the design (schematics and layout).

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

National Semiconductor replaced this model NS103 soon with the NS103A featuring more convenient [ON] and [OFF] keys instead the power switch and removing the [A], [B], and [C] keys from the continuous memories. The early Mitsubishi M58490P chip was replaced with a NEC uPD1833G circuit that was used with many other Account Manager calculators like the Canon Checkbook, IMA 130CBW, Radio Shack EC-306, Royal LCB 841, Texas Instruments TI-2200 Checkwriter, and Unisonic LC 263CK.

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.

Account Manager Calculator Chips

We have no doubts that Mostek was in 1975 with the introduction of the CheckMaster ahead of time, but we credit National Semiconductor for delivering the first "useful" Account Manager Calculator three years later with the NS103 Data Checker. While the NS103 itself was replaced within just two years, lives its legend on and we even bought in 2020 with the Datexx DB-403 and DB-413 two more recent Checkbook Calculators on Amazon to figure out the improvements and changes in technology and usability during 45 years. Please find with the table below an overview of the single-chip calculator circuits discovered while dismantling all of the Account Manager Calculators featured in the Datamath Calculator Museum frm the humble Corvus CheckMaster to the astonishing Canon Checkbook Recorder storing up to 90 financial transactions including item, date, and amount in three different memory banks:

Please find the schematics of the Radio Shack EC-306 sporting a NEC uPD1833G single-chip calculator circuit here or click on the thumbnail picture on the right.

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

© Joerg Woerner, December 1, 2019. No reprints without written permission.