IBM PCjr From 1984 Keeps Today’s Clocks Running In Sync

November 9, 2021 by Robin Kearey 33 Comments

We’ve gotten used to the fact that the clocks on our internet-connected computers and smartphones are always telling the right time. Time servers, provided by a variety of government agencies as well as tech giants, provide them with the exact time and date thanks to accurate atomic clocks and the clever Network Time Protocol (NTP). But it wasn’t always like this: back in the 1990s when many computers didn’t have an internet connection, we had to adjust our computers’ clocks manually. Go back one more decade, and many PCs didn’t even have a battery-backed clock at all; you either set the proper date and time when the computer booted, or just lived with the fact that all new files were timestamped 01-01-1980.

[Michael Brutman] decided to mix today’s world of network time synchronization with the old world of batteryless PCs, and built an SNTP Time Server that runs on a DOS PC. He tried it with two different hardware setups: a 40 MHz 386 PC from 1993, and the (in)famous IBM PCjr from 1984. A standard GPS module serves as an accurate time reference; these units can often be directly connected to old hardware thanks to the eternal RS-232 standard.

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Network Time Clock For A Home Media Center

August 22, 2012 by Brian Benchoff 22 Comments

[Derek] wanted a clock for his media center. A simple wish, but he had a few requirements: he didn’t need an alarm, wanted it to automatically set its time after a power outage, needed a big display, and also wanted it to look good. After shopping around [Derek] couldn’t find a clock that would fit his requirements so he decided to build one.

[Derek]’s project is called the SNTP clock. As you might expect, it gets its name from the protocol used to automatically synchronize the clock in your computer with other network time servers. The clock itself is built around an ATMega168 gathering time data from the Internet with the help of a Lantronics XPort. One inch seven segment LEDs serve as the display for the clock, and everything, from the time offset from UTC, the brightness of the display, and whether the clock displays 12 or 24-hour time is controlled by an infrared Apple remote.

A bare PCB or bundle of wires would look out of place in [Derek]’s media shelf, so he used a metal picture frame and smoked acrylic to dress up his clock. Now he’s got a beautiful and elegant clock that fits right in to his media servers and receiver.