Early Electronic Calculator Texas Instruments SN3900 / SN4500 Series Integrated Circuits

One of TI's standard DTL series. This series contained many more devices than the few presented here.

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.