Macintosh IIx (1988)
The Macintosh IIx was introduced by Apple Computer in 1988 as an incremental update of the original Macintosh II model. It replaced the 16 MHz Motorola 68020 CPU and 68881 FPU of the II with a 68030 CPU and 68882 FPU (running at the same clock speed); and the 800 KB floppy drive with the 1.44 MB SuperDrive (in fact, it was the first Mac to have one). The initial price of the IIx was US$7,769 or $9,300 for a version with the 40 MB hard disk drive. The Mac IIx sported 0.25 KiB of L1 instruction CPU cache, 0.25 KiB of L1 data cache, a 16 MHz bus (1:1 with CPU speed), and supported up to System 7.5.5.
via Wikipedia: http://en.wikipedia.org/wiki/Macintosh_IIx