DATAMATH  CALCULATOR  MUSEUM

National Semiconductor NS103 Data Checker

Date of introduction:  May 1978 Display technology:  LCD
New price:  $34.95 (SRP May 1978) Display size:  8
Size:  2.8" x 6.0" x 0.30"
 71 x 153 x 8 mm3
   
Weight:  2.8 ounces, 79 grams Serial No:  2433168
Batteries:  2*LR44  Date of manufacture:  mth 01 year 1979
AC-Adapter:   Origin of manufacture:  Taiwan
Precision:  8  Integrated circuits:  Mitsubishi  M58490P
Memories:  3    
Program steps:   Courtesy of:  Joerg Woerner
    Download manual:   (US: 1.6 MByte)

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:

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

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:

Part

Intro.

Power Supply

Memories

Additional Features

Calculators

Mostek
MK6225N
1975 6*AAA cells 1 Fixed two-place decimal Corvus CheckMaster
Mitsubishi
M58490P
1978 2*LR44 3 Fixed two-place / Floating point decimal, Percent, Constant National Semiconductor NS103, Unisonic LC 262
NEC
uPD18xxG
1979 2*LR43 2+1 Floating point decimal, Percent, Constant, [ON/OFF] keys, Conversion Memory National Semiconductor NS107
NEC
uPD1831G
1980 2*LR54 1 Fixed 0...4-place / Floating point decimal, Percent, Constant, [ON/OFF] keys NSC Novus Electronics NS101A, Royal LCB 835
(Canon F-32, TI-1744)
NEC
uPD1832G
1980 2*LR54
2*LR43
1 Floating point decimal, Percent, Constant, [ON/OFF] keys Alco LC-127A, APF M3552CK, NSC Novus Electronics NS100A, Royal LCB 830, Unisonic LC 224CKE
(Toshiba LC-827)
NEC
uPD1833G
1980 2*LR44
2*LR43
2*LR54
3 Fixed two-place / Floating point decimal, Percent, Constant, [ON/OFF] keys National Semiconductor NS103A, NSC Novus Electronics NS103A,
Aurora CB-900, Canon Checkbook, IMA 130CBW, Radio Shack EC-306, Royal LCB 841, TI-2200, Tandy EC-306, Unisonic LC 262CK, LC 263CK
Sharp
LI3329MT
1981 2*LR54 1 Percent, Constant, Square Root, [ON/OFF] keys Enterprex MC-2717,
Unisonic LC 224CK
Hitachi
HD43570
1983 CR2025 2+1 Percent, Constant, [ON/OFF] keys, Full Memory Casio CB-80
NEC
uPD1826G-009
1983 CR2025 5+1 Percent, Constant, [ON/OFF] keys, Full Memory Casio CB-100
Toshiba
T7752S
1985 LR55
LR43
3 Fixed two-place / Floating point decimal, Percent, Constant, [ON/OFF] keys, Password Canon Checkbook II, Radio Shack EC-308, EC-430, TI-2200 II, TI-2200+
Sharp
LI3330MT
1987 2*LR54 1 Percent, Constant, [ON/OFF] keys, Mark-Up, Tax Royal CBC 70,
Unisonic LC 226CK
Toshiba
T9840
1988 CR2025 3+90 Fixed two-place / Floating point decimal, Constant, [ON/OFF] keys, Password, 90 transactions memory, 12 different categories, Clock and Calendar, Search function Canon Checkbook Recorder
Sharp
LI3154
1995 LR54 1 Percent, Constant, Square Root, [ON/OFF] keys, Tax Radio Shack EC-455
(TI-1795+)
Unknown
Unknown
2000 CR2025 3 Fixed two-place / Floating point decimal, Percent, Constant, [ON/OFF] keys, Password Bedol Checkmaster Standard
Unknown
Unknown
2000 2*LR43 3+60 Percent, Constant, [ON/OFF] keys, Full Memory, 3*20 transaction memory, Clock and Calendar, Tax Calculation Datexx DB-413,
Radio Shack 65-504
Unknown
T66L16
2002 2*LR43 3+60 Percent, Constant, [ON/OFF] keys, Full Memory, 3*20 transaction memory, Clock and Calendar, Tax Calculation Datexx DB-413,
Radio Shack 65-504A
Unknown
Unknown
2003 LR54 3 Fixed two-place / Floating point decimal, Percent, Constant, [ON/OFF] keys, [Backspace] key Datexx DB-403
ELAN
ePS6500
2008 LR54 1+100 Floating point decimal, Constant, Auto Power Off, [Key Lock] key Datexx DC-80
NXP (Hitachi)
LH75411
2009 PD2440 (3.7V) 1000's It is a computer,
not a calculator.
AccuBalance Corp. AccuBalance

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.