Early Electronic Calculator Texas Instruments SN3900 / SN4500 Series Integrated Circuits

A series of DTL devices from TI.

Pinouts for devices in this series correlate to standard 800/900 series DTL. Also, SN15846 (846 quad 2-in NAND DTL) ICs have been observed in place of SN3925 in a Canon 163 calculator.

The difference then, between this series and standard 800/900 series DTL is not known. There may be no functional difference. These may be units selected for consumer-grade service, or just stamped with part numbers specifically for Canon.

Known Devices:	SN3920, SN3925, SN3931, SN4552, SN4553, SN4554, SN4555, SN4556.
Period:	Late 1960s to early 1970s.
Source of Data:	Data for these devices was obtained from a data sheet for the Monroe 925 and reverse engineering of a Canon EP151 and Canon 163.
Technology:	Standard DTL.
Supply Voltage:	+5 V.
Logic:	Gate symbols are presented in accordance with TRUE = +5V FALSE = 0V Some devices have single-ended outputs with internal pull-up resistors, some have totem-pole outputs.
Packaging:	Standard DIP.

Notes:

IC packages as viewed from above.