|Company||Apple Computer Inc.|
|CPU||MOS Technology/SynerTek 6502|
|RAM||48 KB (max 64 KB, with language card)|
|Text modes||40x24, 80x24 (with 80-column card)|
|Graphic modes||6 color at 280x192, 4-bit color at 40x48|
|Colors||40x40-48 (16 colours), 280x192 (6 colours)|
The Apple II Plus was the second model of the Apple II series of personal computers produced by Apple Computer, Inc.
The Apple II+ had a total of 48 KB of RAM, expandable to 64 KB by means of the language card, an expansion card that could be installed in the computer's slot 0. The Apple's 6502 microprocessor could support a maximum of 64 KB of memory, and a machine with 48 KB RAM reached this limit because of the additional 16 KB of read-only memory and 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 LOGO, the UCSD Pascal and FORTRAN 77 compilers. Apple's Pascal and FORTRAN ran under a non-DOS operating system called the UCSD P-System, which had its own disk format and included a "virtual machine" that allowed it to run on many different types of hardware.
The Apple II Plus 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 (though it ran at a noticeably slower speed than Steve Wozniak's Integer BASIC) and became the standard BASIC dialect on the Apple.
Like the Apple II, the Apple II Plus had no lowercase functionality. All letter keys on the keyboard would type uppercase letters, and there were no lowercase letters in the text-mode font stored in the computer's ROM. (Note the lack of a caps lock key on the keyboard.) To display lowercase letters, some applications would run in the slower hi-res graphics mode and use a custom font, rather than running in the fast text mode using the font in ROM. Other programs used inverse text mode to represent text that would be lowercase when printed. Alternatively, users could install a custom ROM chip that contained lowercase letters in the font, or purchase one of several third-party 80-column cards that enabled a text mode that could display 80-column, upper- and lower-case text. The "Videx Videoterm" card and its many clones were especially popular. For lowercase input, since it was not possible to detect whether the keyboard's Shift keys were in use, a modification called the "one-wire shift key mod" connected the Shift key to one of the pins on the motherboard's joystick connector. Compatible applications, including nearly all word processors, could then detect whether the Shift key was being pressed. This modification, however, involved adding wires inside the Apple II, and was therefore only popular among hobbyists. For this reason, most applications that could support lower-case letters could also use the ESC key as a substitute lowercase toggle if the "shift key mod" was not installed. The II+ had a metal case with brass mesh running along the inside of the case. This mesh protected the computer from harmful radio frequency energy. Velcro was used to hold the case's top onto the computer.