The Apple II Plus, introduced in June 1979, included the Applesoft BASIC programming language in ROM. This Microsoft-authored dialect of BASIC, which was previously available as an upgrade, supported floating-point arithmetic, and became the standard BASIC dialect on the Apple II series (though it ran at a noticeably slower speed than Steve Wozniak's Integer BASIC).
The Apple II Plus was otherwise identical to the original Apple II. The smaller memory sizes were no longer available, so the II Plus always had a total of 48 kB of RAM, expandable to 64 kB by means of the "language card", a 16 kB RAM expansion card that could be installed in the computer's slot 0. The Apple's 6502 microprocessor could support up to 64 kB of memory, and a machine with 48 kB RAM reached this limit because of the additional 12 kB of read-only memory and 4 kB of I/O addresses. For this reason, the extra RAM in the language card was bank-switched over the machine's built-in ROM, allowing code loaded into the additional memory to be used as if it actually were ROM. Users could thus load Integer BASIC into the language card from disk and switch between the Integer and Applesoft dialects of BASIC with DOS 3.3's INT and FP commands just as if they had the BASIC ROM expansion card. The language card was also required to use the UCSD Pascal and FORTRAN 77 compilers, which were released by Apple at about the same time. These ran under the UCSD p-System operating system, which had its own disk format and emitted code for a "virtual machine" rather than the actual 6502 processor. The UCSD P-system had a curious approach to memory management, which became even more curious on the Apple III.
A TEMPEST approved version of the Apple II Plus called the Microfix was developed in 1980 by the Georgia Tech Research Institute for U.S. Army FORSCOM. Fielded in 1982, the Microfix system was the first tactical system using video disk (Laserdisk) map technology providing zoom and scroll over map imagery coupled with a point database of intelligence data such as order of battle, airfields, roadways, and bridges.
Apple II Europlus and J-Plus
After the success of the first Apple II in the United States, Apple expanded its market to include Europe, Australia and the Far East in 1978, with the Apple II Europlus (Europe, Australia) and the Apple II J-Plus (Japan). In these models, Apple made the necessary hardware, software and firmware changes in order to comply to standards outside of the U.S. The power supply was modified to accept the local voltage, and in the European and Australian model the video output signal was changed from color NTSC to monochrome PAL – an extra video card was needed for color PAL graphics, since the simple tricks Wozniak had used to generate a pseudo-NTSC signal with minimal hardware did not carry over to the more complex PAL system. In the Japanese version of the international Apple, the keyboard layout was changed to allow for Katakana writing (full Kanji support was clearly beyond the capabilities of the machine), but in most other countries the international Apple was sold with an unmodified American keyboard; thus the German model still lacked the umlauts, for example. For the most part, the Apple II Europlus and J-Plus were identical to the Apple II Plus. Production of the Europlus ended in 1983.