- Windows 2.1 (Wikipedia)
It was released with two different variants with differing CPU compatibility, also known as Windows/286 and Windows/386, so the versions are considered to be similar to its predecessor. In comparison, the Windows/386 variant is considered to be better than Windows/286, since it provides support for EMS emulation and is designed to use both conventional and extended memory. Changes to the user interface did not occur in this version, and rather, its performance was increased and enhanced memory management was added. The version is also noted to be the first one to require a hard disk drive. A minor update version, Windows 2.11, was released in March 1989.
- Messier 18 (Wikipedia)
Messier 18 or M18, also designated NGC 6613 and sometimes known as the Black Swan Cluster, is an open cluster of stars in the constellation Sagittarius. It was discovered by Charles Messier in 1764 and included in his list of comet-like objects. From the perspective of Earth, M18 is situated between the Omega Nebula (M17) and the Small Sagittarius Star Cloud (M24).