Texas Instruments PS20/20, slightly larger than a credit card, with one CR2025 battery, this little organizer is a phone data bank, clock and calculator, with 1 KB of memory.

This is an old gadget from 1987: A TI-2100 - a small card-size digital organizer and data bank, that holds contacts and phone numbers, with a clock and calendar, and a calculator. It has a screen similar to a digital watch or LCD calculator.

This was from a time of electronic versions of a paper Day-Timer planner and Rolodex, just before PDAs like the Palm Pilot and pocket computers running Windows CE, and way before modern iPhone and Android smartphones with their built in apps for email, contacts and calendars.

November 11, 1985 - Scanned aerial photos from a flyover to search for barrels or 55 gallon drums or any other hazardous waste - Grid 279 A-C - Plainville, Norton & North Attleborough area, Massachusetts

This is an old gadget from 1992: A TI PS-2100 - a tiny credit card-size digital organizer and data bank, that holds contacts and phone numbers, with a clock and calendar, and a calculator. It has a screen similar to a digital watch or LCD calculator.

This was from a time of electronic versions of a paper Day-Timer planner and Rolodex, just before PDAs like the Palm Pilot and pocket computers running Windows CE, and way before modern iPhone and Android smartphones with their built in apps for email, contacts and calendars.

NE555P is a precision timing circuit capable of producing accurate time delays or oscillation. In the time-delay or mono-stable mode of operation, the timed interval is controlled by a single external resistor and capacitor network. In the a-stable mode of operation, the frequency and duty cycle can be controlled independently with two external resistors and a single external capacitor.

If you are interested in that, you can follow the below link to see it:

www.utmel.com/productdetail/texasinstruments-ne555p-7646480