1991 - diffrence engine #2 is complete

-  Based on Charles Babbage's second design for a mechanical calculating engine, a team at the Science Museum in London sets out to prove that the design would have worked as planned. Led by curator Doron Swade the team built Babbage’s machine in six years, using techniques that would have been available to Babbage at the time, proving that Babbage’s design was accurate and that it could have been built in his day.

-  powerbook laptops. Apple's Macintosh Portable meets with little success in the marketplace and leads to a complete redesign of Apple's line of portable computers. All three PowerBooks introduced featured a built-in trackball, internal floppy drive, and palm rests, which would eventually become typical of 1990s laptop design. The PowerBook 100 was the entry-level machine, while the PowerBook 140 was more powerful and had a larger memory. The PowerBook 170 was the high-end model, featuring an active matrix display, faster processor, as well as a floating point unit. The PowerBook line of computers was discontinued in 2006.