Home  >  Classic Macintosh Section  >  The Macintosh IIx

For more information on the Macintosh II read "The Big Mac: Macintosh II"

View all posts by: Vectronic | View all posts in category: Macintosh History

The Macintosh IIx, codenamed "Spock" and "Stratos", was introduced in September 1988 as an incremental update of the Macintosh II. Apple replaced the 16 MHz 68020 processor and 68881 FPU on the Macintosh II with a 16 MHz 68030 processor and 68882 FPU on the Macintosh IIx. The IIx is the first Mac to include an FDHD (Floppy Disk, High Density) controller.

The addition of the FDHD controller was a major change for the Macintosh. The higher capacity drive is designed to work with early Macintosh disks (400K and 800K) as well as MS-DOS 3.5-inch disks in either 740K or 1.4 MB. The SuperDrive, Apple's marketing name for the 1.4 MB drive, can also read ProDOS-formatted disks. You can place a standard MS-DOS or ProDOS diskette into the SuperDrive and then use a translation facility, like Apple's File Exchange program or later system extensions or utilities, to translate a file on the disk into a format that the Macintosh can understand. The SuperDrive can format 400K, 800K, or 1.4 MB disks. You need a 1.4 MB high-density disk to create a 1.4 MB disk volume. The IIx has two bays for internal floppy disk drives and two floppy disk connectors on the motherboard, but the IIx does not have an external disk drive port. The IIx has one bay for an internal SCSI hard disk that connects to the motherboard through a 50-pin connector.

The Macintosh IIx uses a Motorola 68030 processor chip. The chip operates at 16 MHz, like the 68020 CPU of the Macintosh II, but because of tricks like on-chip data caching, it runs applications 15 percent faster than the 68020. Apple improved the level 1 cache form .25K on the Macintosh II to .5K on the Macintosh IIx. The IIx has an integrated on-chip paged memory management unit (PMMU), which was optional on the Macintosh II. The PMMU is necessary for running A/UX, Apple's multitasking version of Unix.

The IIx is easy to upgrade by removing the top. It has six NuBus slots for expansion. The IIx pictured has a monitor card and a network card.

Disassembled Macintosh IIx

The IIx's 68030 processor sits on top of a 16 MHz, 32-bit bus. Although advertised as a 32-bit computer, the Macintosh IIx ROMs are "dirty," containing some 24-bit code. Running in 32-bit addressing mode requires Mode32. The IIx uses the Motorola 68882 floating-point processor chip. This chip gives twice the performance of the 68881 chip found in the Macintosh II.

68030 CPU (left), 68882 FPU (right)

The IIx uses two 3.6V Lithium batteries that do not require a soldering gun to replace

The IIx has six NuBus slots for expansion. Like the Macintosh II, it has no built-in monitor port. The monitor it can support and the bit depth depends on the NuBus card installed. The IIx has a ROM SIMM slot that must be filled with a IIx ROM. Without this ROM, the computer will not function. The Macintosh II does not use a ROM SIMM. The IIx's ROM SIMM holds the basic "personality" of the computer. Classic Macs like the IIx depended heavily on their ROMs, which made it necessary for Mac OS to patch the ROM whenever Apple wanted to revise their functionality. Apple decided it would be advantageous to introduce the removable ROM SIMM in the IIx to make replacement easier and to avoid the need to patch them the next time Apple revised the standard Mac ROMs or dramatically changed Mac OS. The application of this as an upgrade path was handled haphazardly by Apple and many future Macintosh systems did not have replaceable ROMs. Modern Macs rely extensively on Mac OS loaded in RAM. Furthermore, the use of ROMs to hold important components of the Macintosh operating system was only necessary because sufficient RAM memory was expensive at the time of the introduction of the IIx.

The IIx ROM SIMM (left corner) and RAM

Apple NuBus High Resolution Display Video Card

The Macintosh IIx can support up to 8 MB of RAM using 24-bit addressing. The IIx has eight RAM slots. RAM must be installed in groups of four. The IIx can use 256K, 1 MB, 4 MB, and 16 MB 30-pin SIMMS. The IIx requires special PAL SIMMs when using 4 MB or larger SIMMs. It can address up to 128 MB using these SIMMs, but must use 32-bit addressing in order to go above 8 MB, thus it requires Mode32. A Macintosh IIx with 128 MB RAM has eight 16 MB PAL SIMMs and has Mode32 installed. The Macintosh IIx shipped with a standard 1 MB of RAM.

The IIx has the following built-in ports: two ADB ports, one DB-25 SCSI port, one serial modem port, one serial printer port, and one sound-out port. The IIx does not have a built-in microphone or sound-in port. The IIx has a tiny built-in speaker. The Macintosh IIx originally shipped with Mac OS 6.0.1 and it can support up to Mac OS 7.5.5.

IIx ports

The initial price of the IIx was $7769 with no internal hard drive or $9300 for a version with a 40 MB hard disk drive. Apple offered either a 40 MB or 80 MB internal SCSI hard drive. The IIx has room for up to two internal floppy drives and a half-height 5.25-inch or smaller hard drive.

The Macintosh IIx wasn't a revolutionary computer, but it was a logical extension of the Macintosh II line. It was expensive and used almost exclusively for professional applications. The IIx is unquestionably superior to the original Macintosh II, but it still has some obvious deficiencies other than its astronomical cost. It is an extremely large, heavy computer, weighing in at 24 pounds without a monitor. Its dimensions (5.5-in high x 18.7-in wide x 14.4-in deep) are such that it requires the use of a large desk. The IIx doesn't support 32-bit addressing because its ROM is not 32-bit clean, which limits the amount of RAM the IIx can support (up to 8 MB), even with eight RAM slots. The IIx can take advantage of System 7's virtual memory because it uses a 68030 processor, but the use of 32-bit addressing and access to up to 128 MB RAM requires Mode32. Apple discontinued the IIx in October 1990, about ten months after the retirement of the Macintosh II. Its successor, the Macintosh IIfx, introduced in March 1990, would be even more expensive and would stay on the market for two more years before being discontinued in April 1992.

   Rate this article: