The Macintosh IIx was introduced by Apple 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, like the Mac II, sported 0.25 KiB of L1 CPU cache, a 16 MHz bus (1:1 with CPU speed), and supported up to System 7.5.5.
The IIx was the second of three Macintosh models to be built in this case with 6 NuBus slots; the last was the Macintosh IIfx. Apple's nomenclature of the time used the 'x' to indicate the presence of the '030 CPU as used in the Macintosh IIcx and IIvx.
Apple's codenames for the IIx included "Spock" and "Stratos". Support and spare parts for the IIx were discontinued on August 31, 1998.