OS/2

Background
OS/2 is a series of OS published and developed by both IBM and Microsoft. The first version of the system was launched in 1987 and newer versions were released until 2001. After 1994 the operating system would then be called "OS/2 Warp" due to the addition of several performance and GUI improvements, starting with version 3.0. It was targeted at professional and server computers. IBM discontinued support of the software in 2006.

1st Logo (1993-1994)
Logo: On a black background we see the copyright info of the operating system below. Above there's various boxes with various colored circles with the text "OS/2" inside them wiping from below piece-by-piece. Those boxes then disappear, followed by a bigger version of the logo forming the same way as the previous boxes. The copyright info changes to "Loading, please wait..." a second after the logo is formed.

Technique: The wiping logos.

Music/Sounds: Only on the Multimedia version of the OS:
 * Startup: A "baseball charge" sound played by a trumpet.
 * Shutdown: People clapping.

Availability: Extremely rare. Appears on computers with OS/2 2.1.

2nd Logo (1994-1996)
Logo: On a black background we see a white box. On the top-left corner there's the IBM logo. The OS/2 box from before is seen near the right, rotated about 40 degrees to the left. The text "Times New Roman" is seen below. Below the box there's a copyright notice.

Technique: None.

Music/Sounds:
 * Startup: A low ascending synth note that builds up a sudden orchestra hit.
 * Shutdown: A descending synth.

Availability: Very rare. Only on OS/2 Warp 3 systems.

3rd Logo (1996-2006)
Logo: On a marble background, we see the warped text "Times New Roman WARP" on the center. There's the IBM logo on the top-right.

Technique: None.

Music/Sounds:
 * Startup: A calm synth theme with chimes.
 * Shutdown: A loud whoosh, followed by the same descending synth from before, finished by some twinkles.

Availability: Rare. It is found on OS/2 Warp 4 systems. Due to being the latest version of the OS and having a longer support, it's more easier to find than the previous ones.