Apple IIc Plus

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.

Along its right side is the opening for the built-in 3½-inch floppy drive, which replaced the older 5¼-inch drive.

The rear expansion ports. Note the standard AC-power connector and smaller mini DIN-8 serial ports.

Cosmetic changes were apparent as well. The keyboard layout and style now mirrored that of the Apple IIGS and Macintosh, including an enlarged "Return" key and updated modifier keys (Open and Solid Apple being replaced by "Command" and "Option"). Above the keyboard, the rarely used "40/80" switch was replaced by a sliding volume control (gone was the left side volume-control dial, and as a cost-cutting measure, the audio headphone jack disappeared with it). The case housing and keyboard had been changed to the light-grey Apple platinum color, creating a seamless blend between keyboard and case, making them appear almost as one. The machine, a half pound lighter than the original IIc, weighed in at 7 pounds (3.2 kg).

In the rear of the machine the most obvious change was a three-prong AC plug connector and power switch where the voltage converter had once been, a Kensington security slot at the top left corner, and the standardization of the serial port connectors (changed from DIN-5 to mini DIN-8, but still providing an identical signal). All the same built-in Apple II peripheral equivalents and port functionality of the IIc remained, with the one exception being the floppy port. Whereas the previous IIc could only support one external 5.25-inch floppy drive and (in later models) "intelligent" storage devices such as the UniDisk 3.5, the Apple IIc Plus offered backwards port compatibility and more. Support for the external Apple 3.5 Drive used by the Apple IIGS and Macintosh was now present, and up to two external 5.25-inch floppy drives could be added as well.

Internally, the new motherboard sported a pin connector for an internal modem; however no products ever utilized it. The same memory expansion socket introduced on late-model IIc's was present, although it was not compatible with memory cards designed for the previous system. The ROM firmware (now labeled revision "5", following in the sequence from the original IIc) remained the same size, as did RAM, meaning the machine continued to ship with only 128 KB of memory.

The most criticized aspect of the Apple IIc Plus, even among collectors today, is the lack of an internal 5.25-inch drive. The reason for this is the vast majority of software for the 8-bit Apple II series shipped on 5.25-inch disks (often hardcoded for the medium) making the machine of limited use unless an external 5.25-inch drive is added.

Along the same lines of breaking with standards, most 8-bit Apple II software (particularly games) had been designed to run at 'normal' 1.024 MHz operation, but the IIc Plus ran natively at 4 MHz. While user adjustable, the IIc Plus had no automated method to lock-down or "remember" the CPU speed (e.g. a physical turbo button or software-based Control Panel), meaning it would always default back to 'fast' 4 MHz operation if power cycled, reset or simply warm-booted. Acceleration could only be temporarily disabled with a special key press, making it inconvenient for users to repeatedly lower the clock speed manually (for example, booting games on different floppy diskettes).

Another unpopular change was the removal of the voltage converter. While the built-in power supply made the IIc Plus a more integrated one-piece unit for desktop use, the negative aspect was the loss of the ability to operate the machine from a battery source. This, in turn, eroded the portability aspect of the IIc series–a main selling point even despite its lack of a built-in screen, rooting it further to a desktop-only environment.

The removal of the audio-out jack used for headphones or a speaker was another feature users missed.

• 65C02 running at either 1 MHz or 4 MHz (user-selectable)
• 8 KB SRAM cache (16 KB physical installed; 8 KB for TAG/DATA)
• 8-bit data bus

• 128 KB RAM built-in
  • Expandable from 128 KB to 1.125 MB RAM
• 32 KB ROM built-in

• 40 and 80 columns text, with 24 lines¹
• Low-Resolution: 40×48 (16 colors)
• High-Resolution: 280×192 (6 colors) *
• Double-Low-Resolution: 80×48 (16 colors)
• Double-High-Resolution: 560×192 (16 colors) *

*effectively 140×192 in color, due to pixel placement restrictions

¹Text can be mixed with graphic modes, replacing either bottom 8 or 32 lines, depending on video mode

• Built-in speaker; 1-bit toggling
• User-adjustable volume (manual sliding switch)

• Internal 3.5-inch floppy drive
  • 800 KB, double-sided
  • Motorized ejection/auto-injection

• IIc Plus Memory Expansion Card connector (34-pin)
• Internal modem (7-pin)

• IWM (Integrated Woz Machine) for floppy drives
• MIG (Magic Interface Glue) with 2 KB SRAM, for "dumb" 3.5-inch drive support
• Dual 6551 ACIA chips for serial I/O

• Joystick/Mouse (DE-9)
• Printer, serial-1 (mini DIN-8)
• Modem, serial-2 (mini DIN-8)
• Video Expansion Port (D-15)
• Floppy drive SmartPort (D-19)
• NTSC composite video output (RCA connector)

The Apple IIc Plus had a relatively short product lifespan, produced for only two years (it was officially discontinued in November 1990). Though for many years it was believed that there had been no changes or revisions made to the machine, in 2008 hobbyists discovered the existence of two versions of the motherboard.[4] While the revised board contained several minor differences (mainly different ASIC manufacturers and markings), there were no updates or bug fixes seen in the firmware (which was still identified as ROM version '5').

There were also no international versions of the Apple IIc Plus produced, so the keyboard, unlike the original IIc, was only manufactured with American English printed keycaps and the 'Keyboard' switch was utilized solely for changing between QWERTY and Dvorak layout (rather than localized keyboard layouts). Consequently, the Apple IIc Plus was only sold in the U.S. — not even Canadian Apple dealers were authorized to distribute or sell it.