Power Macintosh 6100 (1994)

The Power Macintosh 6100 is Apple Computer's first computer to use the new PowerPC RISC type processor created by IBM and Motorola. It came in the Centris 610's "pizza box" low-profile case,[1] and superseded the Quadra series that used Motorola's 68040 processor, Apple's previous high end workstation line. It is the earliest Macintosh model able to run Mac OS 9.

via Wikipedia: http://en.wikipedia.org/wiki/Power_Macintosh_6100