This was the first in the long series for the PlayStation and contains Pac-Man (1980), Rally-X (1980), New Rally-X (1981), Galaga (1981), Bosconian (1981), Pole Position (1982), and Toy Pop (1986), which was relatively unknown.
All of the games were ported from the original arcade version's source code - Galaga and Pac-Man allowed for an alternative screenmode to compensate for the lack of vertical monitor, whereby the scoreboard was located on the left of the screen, or rotated the image 90 degrees if the user possessed a vertical monitor or was willing to risk placing the television/monitor on its side. The games in Namco Museum: 50th Anniversary Arcade Collection were emulated using the original game ROMs.
The control systems of six of the games were well preserved. Since the PlayStation's analog controller was not available at the time, and analog control for Pole Position is only supported in this compilation by Namco's neGcon joypad.
The package also featured a "museum" mode where the player could walk through a virtual museum containing various curiosities surrounding the games including images of the mainboards, marketing material and conceptual artwork (all from the Japanese releases; neither this nor the others contain any American materials). For this reason, the games themselves are based on the Japanese releases, although for the U.S. the games retain their U.S. changes (i.e., Pac-Man is still "Pac-Man", as opposed to "Puckman"; the ghosts still have their U.S. names, etc.).
Source: Wikipedia, "Namco Museum," available under the CC-BY-SA License.