Apple IIc Plus

The Apple IIc Plus is the sixth and final model in the Apple II series of personal computers, produced by Apple Computer. The "Plus" in the name was a reference to the additional features it offered over the original portable Apple IIc, such as greater storage capacity (a built-in 3.5-inch floppy drive replacing the classic 5.25-inch drive), increased processing speed, and a general standardization of the system components. In a notable change of direction, the Apple IIc Plus, for the most part, did not introduce new technology or any further evolutionary contributions to the Apple II series, instead merely integrating existing peripherals into the original Apple IIc design. The development of the 8-bit machine was criticized by users more interested in the significantly more advanced 16-bit Apple IIGS.

By 1988 the Laser 128 series of Apple II clones was popular enough that it had, inCider wrote, "won a place in the Apple market, and irritated Apple in the process". The 128 sold for about $300 less than the Apple IIc. The Apple IIc Plus was introduced on September 16, 1988, at the AppleFest conference in San Francisco, with less fanfare than the IIc had received four years earlier. Described as little more than a "turbocharged version of the IIc with a high-capacity 3½ disk drive" by one magazine review of the time, some users were disappointed. Many IIc users already had add-ons giving them something rather close to what the new model offered.

Before the official release of the machine, it had been rumored to be a slotless version of the Apple IIGS squeezed into the portable case of the Apple IIc. Apple employee John Arkley, one of the engineers working on the Apple IIc Plus project, had devised rudimentary plans for an enhanced Apple IIGS motherboard that would fit in the IIc case, and petitioned management for the go-ahead with such a project; the idea was rejected.

Apple priced the IIc Plus much more aggressively than it had the IIc; it was only $126 more expensive than the Laser 128EX/2. When the project started the original plan was to just replace the 5.25-inch floppy drive with a 3.5-inch, without modifying the IIc design. Other features, consequently, were added as the project progressed. It is believed the Apple IIc Plus design, and its existence at all, was influenced by the Laser 128. The Apple IIc Plus is very similar in design to the Laser 128EX/2 model, released shortly before the Apple IIc Plus. As it was fully backwards-compatible, the Apple IIc Plus replaced the Apple IIc.

Codenames for the machine while under development included: Raisin, Pizza, and Adam Ant.

The Apple IIc Plus had comprised three new features compared to the IIc. The first and most noticeable feature was the replacement of the 5.25-inch floppy drive with the new 3.5-inch drive. Besides offering nearly six times the storage capacity (800 KB), the new drive had a much faster seek time (three times faster) and button-activated motorized ejection. To accommodate the increased data flow of the new drive, specialized chip circuitry called the MIG, an acronym for "Magic Interface Glue", was designed and added to the motherboard along with a dedicated 2 KB static RAM buffer (the MIG chip is the only exception to there being no new technological developments present in the machine).

The second most important feature was a faster 65C02 processor. Running at 4 MHz, it made the computer faster than any other Apple II, including the IIGS. Apple licensed the Zip Chip Apple II accelerator from third-party developer Zip Technologies and added to the IIc Plus; instead of the all-in-one tall chip design, Apple engineers broke out the design into its core components and integrated them into the motherboard (a 4 MHz CPU, 8 KB of combined static RAM cache, and logic). Apple stated its performance as three times faster (3.3 times according to benchmarks) than any other 8-bit Apple II. The CPU acceleration was a last-minute feature addition, which in turn made the specialized circuitry for the use of a 3.5-inch drive unnecessary at full CPU speed as the machine was now fast enough to handle the data flow; that circuitry was left in place and put into operation nonetheless to support 1 MHz mode. By default the machine ran at 4 MHz, but holding down the 'ESC' key during a cold or warm boot disabled the acceleration so it could run at a standard 1 MHz operation — necessary for older software that depended on timing, especially games.

The third major change was the internalization of the power supply into the Apple IIc Plus's case, utilizing a new miniature design from Sony and replacing the previous "brick on a leash" external supply design.