Corvus 525 a.k.a. CheckMaster

Date of introduction:  1975 Display technology:  LED-modules
New price:  $39.95 (SRP Oct. 1975) Display size:  6
Size:  3.8" x 2.1" x 0.13"
 94 x 172 x 25 mm3
Weight:  1.4 ounces, 151 grams Serial No:  525-0081597
Batteries:  6*AAA cells Date of manufacture:  mth 06 year 1975
AC-Adapter:   Origin of manufacture:  USA
Precision:  6 Integrated circuits:  Mostek MK6225N
Memories:  1    
Program steps:   Courtesy of:  Hans Bloemen
    Download manual:   (US: 1.9 MByte)

CheckMaster_1.jpg (46313 Byte)The Corvus 525 - better known as CheckMaster - looks different to electronic calculators. No doubt, you can't perform even basic calculations with this rare cutie! The CheckMaster was introduced in 1975 and keeps track of your checkbook. The three dedicated keys


simply add to memory, subtract from memory and display the balance of the memory. 

When not in use the CheckMaster folds together to a stylish and slim unit that keeps the balance in memory even shut off. Due to high power consumption of the memory the CheckMaster is powered by 6 AAA-size batteries.

CheckMaster_PCB.jpg (51391 Byte)Dismantling this CheckMaster manufactured by Mostek in June 1975 reveals a MK6225N custom programmed single-chip calculator circuit, a small 7-segment LED display and lot of space for the batteries. Earlier versions made use of a white ceramic packages for the MK6225N instead the later plastic packages.

Learn more about Mostek Calculator Integrated Circuits.

Within about one year Arizona Digital Corporation of Phoenix, AZ introduced the CB82 Check Tronic Purse Calculator and added basic math functionality to the combination of a permanent (till the 9V battery is empty) memory and a power-hungry LED display.

Another two years later, when low-power CMOS technology was readily available, National Semiconductor introduced with the NS103 Data Checker an electronic record keeper with three continuous memories based on a Mitsubishi single-chip calculator circuit. Early in the Eighties the market took off and a huge variety of calculators appeared on the market with dedicated checkbook functions. Don't miss the TI-1880 Checkwriter, TI-2200, IMA 130CBW, Canon Checkbook and the Radio Shack EC-430.

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

Don't miss "real" calculators of the Corvus brand like the 310, 320, 400, 415, 500, and 615 models and the desktop line 300E, 305, and 307.

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If you have additions to the above article please email:

Joerg Woerner, March 23, 2003. No reprints without written permission.