Editing Apple II Plus

{{Infobox computer
| name                              = Apple II Plus
| image                             = [[File:Apple_II_Plus.jpg|250px]]
| caption                 = Apple II Plus – Enhanced Apple II Series Model
| manufacturer                      = Apple Computer, Inc.
| type                              = Home Computer
| release date                      = June 1979
| discontinued                      = December 1982
| price                             = US$1,195 (1979)
| cpu                               = MOS Technology 6502 @ 1.023 MHz
| memory                            = 48 KB RAM (expandable to 64 KB), 12 KB ROM (Integer BASIC, Applesoft BASIC, Monitor)
| storage                           = External cassette tape, optional 5.25" floppy disk drive (Disk II)
| display                           = 40×24 text, 280×192 graphics (6 colours), 16-colour low-res mode
| sound                             = 1-bit built-in speaker (toggle via software)
| dimensions                        = 38.1 cm × 45.7 cm × 10.2 cm
| weight                            = 5.9 kg
| os                                = Apple DOS 3.2, 3.3; ProDOS (later)
| predecessor                       = [[Apple II]]
| successor                         = [[Apple IIe]]
| codename                          = 
| model                             = A2S1048, A2S1049
}}

The '''Apple II Plus''' is the second model in Apple Computer’s influential Apple II series, introduced in June 1979. It featured expanded memory, the introduction of Applesoft BASIC in ROM, and compatibility with a growing ecosystem of expansion cards, making it a mainstay of home, educational, and business computing into the early 1980s.

== Architecture and Processor ==
At its core, the Apple II Plus is powered by the '''MOS Technology 6502''' microprocessor, running at '''1.023 MHz'''. The 6502 was an 8-bit CPU widely adopted in early personal computers for its simplicity and low cost. The Apple II Plus architecture is fully compatible with the original Apple II, but adds improved firmware and ROM routines.

Key architectural features:
* 8-bit data bus, 16-bit address bus (64 KB addressable space)
* Integer BASIC in ROM replaced by '''Applesoft BASIC''' (floating-point support)
* Built-in system monitor in ROM for low-level programming and diagnostics

== Memory and Storage ==
The standard Apple II Plus shipped with '''48 KB RAM''', expandable to '''64 KB''' via an additional 16 KB language card in slot 0. ROM was expanded to '''12 KB''', containing:
* '''Applesoft BASIC''' (8 KB)
* '''Monitor ROM''' (2 KB)
* '''Autostart ROM''' (2 KB, for improved booting and disk support)

Storage options included:
* '''Cassette tape interface''' (standard, for program and data storage)
* Optional '''Disk II 5.25" floppy drive''' (introduced in 1978, widely adopted by II Plus users)
* Third-party and later Apple expansion cards enabled hard disk, RAM disk, and other storage forms

== Display and Graphics ==
The Apple II Plus used the same video subsystem as the original Apple II, providing:
* '''Text modes''': 40 columns × 24 rows (upper/lowercase with third-party mods)
* '''Low-resolution graphics''': 40×48 pixels, 16 colours
* '''High-resolution graphics''': 280×192 pixels, 6 colours (colour availability depends on NTSC artifacting)
* Composite video output for direct connection to colour or monochrome monitors and televisions

The graphics system was memory-mapped, allowing direct manipulation of the display by software.

== Sound Capabilities ==
Sound on the Apple II Plus was simple but effective for its era:
* '''1-bit built-in speaker''', toggled by writing to a memory-mapped address ($C030)
* Programmable by software for single-channel beeps, clicks, and simple tones
* More advanced sound (multi-voice, music, speech) was possible with third-party sound cards and peripherals

== Input/Output and Expansion ==
The Apple II Plus was renowned for its expandability, featuring '''eight internal expansion slots''' for peripherals such as:
* Disk II controller cards (for floppy drives)
* Language cards (RAM expansion)
* Serial and parallel interface cards (printers, modems)
* Video and graphics enhancements
* Sound and speech synthesiser cards
* Networking and hard disk controllers

Standard I/O ports included:
* '''Composite video output'''
* '''Cassette in/out'''
* '''Game I/O connector''' (paddle/joystick support)
* '''Keyboard''' (built-in)
* '''Expansion slots (8)'''

== PCB Schematics & Service Manual ==
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The Apple II Plus main logic board is a single-sided PCB integrating the CPU, RAM, ROM, video, and bus logic. Several revisions exist, with minor changes to support additional RAM or improved reliability.

{| class="wikitable styled-table" style="width:80%; text-align:center;"
! Logic Board !! Schematic Diagrams
|-
| [[File:Apple II j-plus Main Logic Board.jpeg|center|thumb|472x472px|Apple II Plus Logic Board]]
| [[File:Apple_II_Plus_Schematic.png|center|thumb|350x350px|Apple II Plus Logic Board Schematic]]
|}

The official '''Apple II Plus Reference Manual''' and '''Apple II Plus Technical Reference Manual''' provide comprehensive schematics, troubleshooting, and service procedures.

== Gallery ==
<gallery mode="packed" heights="200">
File:Apple II Plus.jpg|Apple II Plus front view
File:Apple II Euro Plus mit Laufwerken.JPG|Apple II Plus with Disk Drives
File:Apple II j-plus Main Logic Board.jpeg|Apple II Plus motherboard
</gallery>

[[Category:Apple Vintage Computers]]
{{Navbox-AppleVintage}}

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