Editing Apple II (original)

{{Short description|First model in the Apple II computer series}}
{{About|the first mass-produced Apple computer|the series of computers|Apple II}}
{{Use mdy dates|date=June 2019}}
{{Infobox information appliance
| logo = Apple2Logo.svg
| image = Apple II typical configuration 1977.png
| caption = A common 1977 configuration, with a 9" monochrome monitor, game paddles, and a Red Book-recommended [[Panasonic]] RQ-309DS cassette deck
| developer = [[Steve Wozniak]] (lead designer)
| manufacturer = [[Apple Inc.|Apple Computer, Inc.]]
| family = [[Apple II]]
| releasedate = {{Start date and age|1977|6}}<ref name="hist70">{{Cite web |last=Weyhrich |first=Steven |date=2010-07-10 |title=1969-1977 |url=http://apple2history.org/appendix/ahb/ahb1/ |access-date=2016-10-02 |publisher=Apple II History |archive-date=May 17, 2022 |archive-url=https://web.archive.org/web/20220517004444/http://www.apple2history.org/appendix/ahb/ahb1/ |url-status=live }}</ref>
| price = {{US$|1298|1977|round=-1}}
| discontinued = {{End date and age|1979|5}}
| os = [[Integer BASIC]] / [[Apple DOS]]
| cpu = [[MOS Technology 6502]] <br /> @ {{nowrap|1.023 MHz}}
| storage = [[Compact  Cassette|Audio cassette]],<br />[[Disk II]] (5.25-inch, 140&nbsp;KB, Apple)
| memory = 4, 8, 12, 16, 20, 24, 32, 36, 48, or 64&nbsp;KiB
| display = [[NTSC]] video out (built-in [[RCA connector]])
| graphics = Lo-res: 40×48, 16-color<br />Hi-res: 280×192, 8-color<ref name="laboratorium.net">{{cite web | url=http://laboratorium.net/archive/2009/03/08/why_did_the_applie_ii_have_six_colors#comment-70109 | title=The Laboratorium : Why Did the Apple II Have Six Colors? }}</ref>
| sound = 1-bit speaker (built-in)<br />1-bit cassette input (built-in [[microphone jack]])<br />1-bit cassette output (built-in [[headphone jack]])
| input = Upper-case keyboard, 52 keys
| controllers = [[Paddle (game controller)|Paddles]]
| connectivity = [[Parallel port]] card (Apple and third party); [[Serial port]] card (Apple and third party); [[SCSI]]
| predecessor = [[Apple I]]
| successor = [[Apple II Plus]]
}}

[[File:Micromodem II in Apple II.jpg|thumb|240px|An Apple II computer with an external [[modem]] ]]

The '''Apple II''' (stylized as {{nowrap|'''apple ]['''}}) is a [[personal computer]] released by [[Apple Inc.]] in June 1977. It was one of the first successful mass-produced [[microcomputer]] products and is widely regarded as one of the most important personal computers of all time due to its role in popularizing [[Home computer|home computing]] and influencing later [[software]] development.<ref>{{cite magazine|url= http://www.pcworld.com/article/id%2C126692-page%2C10-c%2Csystems/article.html|magazine=PC World|title=The 25 Greatest PCs of All Time|archive-url=https://web.archive.org/web/20080511194506/http://www.pcworld.com/article/id,126692-page,10-c,systems/article.html#II|archive-date=2008-05-11}}</ref><ref>{{Cite web |date=2012-09-25 |title=10 Most Popular Computers in History |url=https://computer.howstuffworks.com/10-most-popular-computers-in-history.htm |access-date=2024-03-06 |website=HowStuffWorks |language=en-us}}</ref><ref>{{Cite web |date=2021-08-12 |title=The Most Important PCs in History, Ranked |url=https://www.digitaltrends.com/computing/most-important-personal-computers-in-history/ |access-date=2024-03-06 |website=Digital Trends |language=en}}</ref><ref>{{Cite news |last=Stuart |first=Keith |date=2020-09-07 |title=The 20 greatest home computers – ranked! |url=https://www.theguardian.com/games/2020/sep/07/the-20-greatest-home-computers-ranked |access-date=2024-03-06 |work=The Guardian |language=en-GB |issn=0261-3077}}</ref><ref>{{Cite news |last=Reimer |first=Jeremy |date=December 14, 2005 |title=Total share: 30 years of personal computer market share figures |work=[[Ars Technica]] |url=https://arstechnica.com/articles/culture/total-share.ars/3 |access-date=May 25, 2010 |archive-date=December 4, 2008 |archive-url=https://web.archive.org/web/20081204091105/http://arstechnica.com/articles/culture/total-share.ars/3 |url-status=live }}</ref>

The Apple II was designed primarily by [[Steve Wozniak]]. The system is based around the [[8-bit]] [[MOS Technology 6502]] microprocessor. Jerry Manock designed the foam-molded plastic case,<ref name="JobsBio1">{{Cite book |last=Isaacson |first=Walter |title=Steve Jobs |title-link=Steve Jobs (book) |publisher=Simon & Schuster |year=2011 |isbn=9781451648546 |oclc=859338048 |author-link=Walter Isaacson}}</ref> [[Rod Holt]] developed the [[Switched-mode power supply|switching power supply]],<ref name="wozorg">{{Cite web |last=Wozniak |first=Steve |title=Comment From e-mail: Why didn't the early Apple II's use Fans? |url=http://archive.woz.org/letters/general/35.html |url-status=dead |archive-url=https://web.archive.org/web/20151226203330/http://archive.woz.org/letters/general/35.html |archive-date=2015-12-26 |access-date=2015-05-10 |publisher=woz.org}}</ref> while [[Steve Jobs]] was not involved in the design of the computer.<ref>{{Cite web |date=2015-09-02 |title=Steve Jobs 'played no role at all' in designing the Apple I or Apple II computers, Woz says |url=http://finance.yahoo.com/news/steve-jobs-played-no-role-212749041.html |access-date=2023-12-05 |website=Yahoo Finance |language=en-US}}</ref> It was introduced by Jobs and Wozniak at the 1977 [[West Coast Computer Faire]], and marks Apple's first launch of a computer aimed at a consumer market—branded toward American households rather than businessmen or computer hobbyists.<ref name=":0">{{Cite journal |last=Stein |first=Jesse Adams |year=2011 |title=Domesticity, Gender and the 1977 Apple II Personal Computer |journal=Design and Culture |volume=3 |issue=2 |pages=193–216 |doi=10.2752/175470811X13002771867842 |hdl-access=free |hdl=10453/30296 |s2cid=143648126}}</ref>

[[File:Home or Personal Computers from 1977 - Commodore PET 2001, Apple II, TRS-80 Model I, together called 'Trinity77' (edited image).jpg|thumb|406x406px|The three computers that ''Byte'' magazine referred to as the "1977 Trinity" of home computing: Commodore PET 2001, Apple II, and TRS-80 Model I]]

[[Byte (magazine)|''Byte'']] magazine referred to the Apple II, [[Commodore PET|Commodore PET 2001]], and [[TRS-80]] as the "1977 Trinity".<ref>{{Cite magazine |date=September 1995 |title=Most Important Companies |magazine=[[Byte (magazine)|Byte]] |url=http://www.byte.com/art/9509/sec7/art15.htm |access-date=2008-06-10 |archive-url=https://web.archive.org/web/20080618072507/http://www.byte.com/art/9509/sec7/art15.htm |archive-date=2008-06-18}}</ref> As the Apple II had the defining feature of being able to display color graphics, the [[Apple logo]] was redesigned to have a [[spectrum]] of colors.<ref>{{cite web|title=Apple II History Chapter 4 |url=http://apple2history.org/history/ah04.html |author=Steven Weyhrich |date=April 21, 2002 |access-date=November 16, 2006 |url-status=dead |archive-url=https://web.archive.org/web/20060925003021/http://apple2history.org/history/ah04.html |archive-date=September 25, 2006 }}</ref><ref>{{cite web |title=Interview with Rob Janoff, designer of the Apple logo |url=https://creativebits.org/interview/interview_rob_janoff_designer_apple_logo/ |date=July 20, 2020 |access-date=September 12, 2020 |archive-date=October 24, 2017 |archive-url=https://web.archive.org/web/20171024013734/http://creativebits.org/interview/interview_rob_janoff_designer_apple_logo |url-status=live }}</ref>

The Apple II was the first in a series of computers collectively referred to by the [[Apple II]] name. It was followed by the [[Apple II Plus|Apple II+]], [[Apple IIe]], [[Apple IIc]], [[Apple IIc Plus]], and the 16-bit [[Apple IIGS]]—all of which remained compatible. Production of the last available model, the Apple IIe, ceased in November 1993.<ref name="hist90">{{Cite web |last=Weyhrich |first=Steven |date=May 16, 2003 |title=1990-1995 |url=https://apple2history.org/appendix/ahb/ahb5/ |access-date=May 25, 2010 |publisher=Apple II History |archive-date=August 19, 2010 |archive-url=https://web.archive.org/web/20100819190221/http://apple2history.org/appendix/ahb/ahb5/ |url-status=live }}</ref>

==History==
By 1976, Steve Jobs had convinced product designer Jerry Manock (who had formerly worked at Hewlett Packard designing calculators) to create the "shell" for the Apple II—a smooth case inspired by kitchen appliances that concealed the internal mechanics.<ref name=":0" /> The earliest Apple II computers were assembled in [[Silicon Valley]] and later in Texas;<ref>{{Cite book |last=Rose |first=Frank |title=West of Eden |publisher=Arrow Books |year=1989 |isbn=0-09-976200-5 |page=3}}</ref> [[printed circuit board]]s were manufactured in [[Republic of Ireland|Ireland]] and [[Singapore]]. The first computers went on sale on June 10, 1977<ref name="Apple II intro date">{{Cite web |title=June 10, 1977 - Apple II Released Today |url=http://www.computerhistory.org/tdih/June/10/ |access-date=August 3, 2012 |website=This Day in History |publisher=Computer History Museum |location=Mountain View, CA |archive-date=June 20, 2012 |archive-url=https://web.archive.org/web/20120620175048/http://www.computerhistory.org/tdih/June/10/ |url-status=live }} June 10, 1977 was a Friday.</ref><ref name="Apple II History">{{Cite web |last=Weyhrich |first=Steven |title=4-The Apple II, cont. - Product Introduction |url=http://apple2history.org/history/ah04/ |access-date=August 3, 2012 |website=Apple II History |date=December 2008 |publisher=Apple2History.org |quote=The first motherboard-only Apple II computers shipped on May 10, 1977, for those who wanted to add their own case, keyboard, and power supply (or wanted to update their Apple-1 'system' with the latest and greatest). A month later, on June 10, 1977, Apple began shipping full Apple II systems. |archive-date=May 22, 2015 |archive-url=https://web.archive.org/web/20150522020820/http://apple2history.org/history/ah04/ |url-status=live }}</ref> with an [[MOS Technology 6502]] microprocessor running at 1.023 [[MHz]] ({{frac|2|7}} of the [[Colorburst|NTSC color subcarrier]]), two [[Paddle (game controller)|game paddles]]<ref name="helmers197803" /> (bundled until 1980, when they were found to violate [[Title 47 CFR Part 15|FCC regulations]]),<ref name="ccvag1983spring">{{Cite magazine |last1=Ahl |first1=David H. |author-link=David H. Ahl |last2=Rost |first2=Randi J. |year=1983 |title=Blisters And Frustration: Joysticks, Paddles, Buttons and Game Port Extenders for Apple, Atari and VIC |url=https://www.atarimagazines.com/cva/v1n1/joysticks.php |magazine=Creative Computing Video & Arcade Games |volume=1 |issue=1 |pages=106ff |access-date=2021-01-28 |author2-link=Randi J. Rost |archive-date=February 24, 2021 |archive-url=https://web.archive.org/web/20210224144058/https://www.atarimagazines.com/cva/v1n1/joysticks.php |url-status=live }}</ref> 4&nbsp;KiB of [[random-access memory|RAM]], an [[Cassette tape#Data recording|audio cassette]] interface for loading programs and storing data, and the [[Integer BASIC]] programming language built into [[read-only memory|ROMs]]. The video controller displayed 24 lines by 40 columns of monochrome, uppercase-only text on the screen (the original character set matches [[ASCII]] characters 20<sub>h</sub> to 5F<sub>h</sub>), with [[NTSC]] [[composite video]] output suitable for display on a video monitor or on a regular TV set (by way of a separate [[RF modulator]]).

The original retail price of the computer with 4 KiB of RAM was {{US$|1298|1977|round=-1}}<ref>{{Cite book |last1=Forster |first1=Winnie |authorlink1=Winnie Forster |title=The Encyclopedia of Consoles, Handhelds & Home Computers 1972–2005 |publisher=Gameplan |year=2005 |isbn=3-00-015359-4 |page=19}}</ref> and with the maximum 48&nbsp;KiB of RAM, it was {{US$|2638|1977|round=-1}}<ref name="Avidd Pricelist">[[:File:AVIDD Apple price list 1977 front.jpg|1977 Apple II price list]] A-VIDD Electronics Co., 1977 Long Beach, CA.</ref> To reflect the computer's [[Apple II graphics|color graphics]] capability, the Apple logo on the casing has rainbow stripes,<ref>{{Cite web |last=Weyhrich |first=Steven |date=April 21, 2002 |title=4-The Apple II, cont. |url=http://apple2history.org/history/ah04.html |url-status=dead |archive-url=https://web.archive.org/web/20060925003021/http://apple2history.org/history/ah04.html |archive-date=September 25, 2006 |access-date=November 16, 2006 |publisher=Apple II History}}</ref> which remained a part of Apple's corporate logo until early 1998. Perhaps most significantly, the Apple II was a catalyst for personal computers across many industries; it opened the doors to software marketed at consumers.<ref name=":0" />

Certain aspects of the system's design were influenced by [[Atari, Inc.]]'s [[arcade video game]] ''[[Breakout (video game)|Breakout]]'' (1976), which was designed by Wozniak, who said: "A lot of features of the Apple II went in because I had designed ''Breakout'' for Atari. I had designed it in hardware. I wanted to write it in software now".<ref>Connick, Jack: "...And Then There Was Apple". Call-A.P.P.L.E. Oct 1986: 24.</ref> This included his design of color graphics circuitry, the addition of game paddle support and sound, and graphics commands in [[Integer BASIC]], with which he wrote ''Brick Out'', a software clone of his own hardware game.<ref name="wozniak20140501">{{cite web | url=https://gizmodo.com/how-steve-wozniak-wrote-basic-for-the-original-apple-fr-1570573636 | title=How Steve Wozniak Wrote BASIC for the Original Apple From Scratch | publisher=Gizmodo | date=2014-05-01 | access-date=2 May 2014 | author=Wozniak, Steve | archive-date=May 2, 2014 | archive-url=https://web.archive.org/web/20140502050217/http://gizmodo.com/how-steve-wozniak-wrote-basic-for-the-original-apple-fr-1570573636 | url-status=live }}</ref> Wozniak said in 1984: "Basically, all the game features were put in just so I could show off the game I was familiar with—''Breakout''—at the [[Homebrew Computer Club]]. It was the most satisfying day of my life [when] I demonstrated ''Breakout''&mdash;totally written in BASIC. It seemed like a huge step to me. After designing hardware [[arcade games]], I knew that being able to program them in BASIC was going to change the world."<ref name="wozniak198412">{{cite magazine | url=https://archive.org/stream/byte-magazine-1984-12/1984_12_BYTE_09-13_Communications#page/n461/mode/2up | title=The Apple Story / Part 1: Early History | magazine=[[Byte (magazine)|BYTE]] | volume=9 | issue=13 | date=December 1984 | access-date=23 October 2013 |author1=Williams, Gregg |author2=Moore, Rob | pages=A67 | type=interview}}</ref>

==Overview==
In the May 1977 issue of [[Byte (magazine)|''Byte'']], [[Steve Wozniak]] published a detailed description of his design; the article began, "To me, a personal computer should be small, reliable, convenient to use, and inexpensive."<ref name="wozniak197705">{{Cite magazine |last=Wozniak |first=Steve |date=May 1977 |title=System Description / The Apple-II |pages=34–43 |magazine=[[Byte (magazine)|BYTE]] |volume=2 |issue=5 |url=https://archive.org/stream/byte-magazine-1977-05/1977_05_BYTE_02-05_Interfacing#page/n35/mode/2up |access-date=October 17, 2013}}</ref>

The Apple II used peculiar engineering shortcuts to save hardware and reduce costs, such as:
* Taking advantage of the way the 6502 processor accesses memory: it occurs only on alternate phases of the clock cycle; video generation circuitry memory access on the otherwise unused phase avoids memory contention issues and interruptions of the video stream;
* This arrangement simultaneously eliminated the need for a separate [[Memory refresh|refresh]] circuit for [[Dynamic random-access memory|DRAM]] chips, as video transfer accessed each row of dynamic memory within the [[Memory refresh#Refresh interval|timeout]] period. In addition, it did not require separate RAM chips for video RAM, while the PET and TRS-80 had SRAM chips for video;
* Apart from the 6502 CPU and a few support chips, the vast majority of the semiconductors used were 74LS low-power Schottky chips;
* Rather than use a complex [[analog-to-digital]] circuit to read the outputs of the game controller, Wozniak used a simple timer circuit, built around a quad [[555 timer IC]] called a 558, whose period is proportional to the resistance of the game controller, and he used a software loop to measure the timers;
* A single 14.31818&nbsp;MHz master oscillator (f<sub>M</sub>) was divided by various ratios to produce all other required frequencies, including microprocessor clock signals (f<sub>M</sub>/14), video transfer counters, and color-burst samples (f<sub>M</sub>/4). A solderable jumper on the main board allowed to switch between European 50&nbsp;Hz and USA 60&nbsp;Hz video.

The text and graphics screens have a complex arrangement. For instance, the scanlines were not stored in sequential areas of memory. This complexity was reportedly due to Wozniak's realization that the method would allow for the refresh of dynamic RAM as a side effect (as described above). This method had no cost overhead to have software calculate or look up the address of the required scanline and avoided the need for significant extra hardware. Similarly, in high-resolution graphics mode, color is determined by pixel position and thus can be implemented in software, saving Wozniak the chips needed to convert bit patterns to colors. This also allowed the ability to draw text with [[subpixel rendering]], since orange and blue pixels appear half a pixel-width farther to the right on the screen than green and purple pixels.<ref>{{Cite web |last=Gibson |first=Steve |title=The origins of sub-pixel font rendering |url=http://www.grc.com/ctwho.htm |url-status=live |archive-url=https://web.archive.org/web/20060721130149/http://www.grc.com/ctwho.htm |archive-date=July 21, 2006 |access-date=August 4, 2006 |publisher=Gibson Research Corporation}}</ref>

The Apple II at first used [[data cassette]] storage, like most other microcomputers of the time. In 1978, the company introduced an external {{frac|5|1|4}}-inch [[floppy disk]] drive, called [[Disk II]] (stylized as Disk ][), attached through a controller card that plugs into one of the computer's [[expansion slot]]s (usually slot 6). The Disk II interface, created by Wozniak, is regarded as an engineering masterpiece for its economy of electronic components.<ref>{{Cite web |last=Weyhrich |first=Steven |date=December 28, 2001 |title=5-The Disk II |url=http://apple2history.org/history/ah05.html |url-status=dead |archive-url=https://web.archive.org/web/20061201122002/http://apple2history.org/history/ah05.html |archive-date=December 1, 2006 |access-date=November 16, 2006 |publisher=Apple II History}}</ref><ref>{{Cite book |last1=Freiberger |first1=Paul |title=Fire In The Valley, Part Two |last2=Swaine |first2=Michael |date=January 1985 |work=A+ Magazine |page=45 |type=Book excerpt |author-link=Paul Freiberger |author-link2=Michael Swaine (technical author)}}</ref>

The approach taken in the Disk II controller is typical of Wozniak's designs. With a few small-scale logic chips and a cheap PROM ([[programmable read-only memory]]), he created a functional floppy disk interface at a fraction of the component cost of standard circuit configurations.

==Case design==
The first production Apple II computers had hand-molded cases; these had visible bubbles and other lumps in them from the imperfect plastic molding process, which was soon switched to machine molding.<ref>{{Cite book |editor-last1=Laurel |editor-first1=Brenda |editor-last2=Mountford |editor-first2=S. Joy |url=http://worldcat.org/oclc/490225229 |title=The art of human-computer interface design |date=1990 |publisher=Addison-Wesley Pub. Co |isbn=0-201-51797-3 |oclc=490225229}}</ref> In addition, the initial case design had no vent openings, causing high heat buildup from the [[printed circuit board]] (PCB) and resulting in the plastic softening and sagging. Apple added vent holes to the case within three months of production; customers with the original case could have them replaced at no charge.

==PCB revisions==
[[File:Apple II motherboard (53171103722).jpg|thumb|left|An Apple II PCB. The white rectangle outline near the middle surrounds the three RAM banks, here all loaded with 16kx1 DRAMs.]]
The Apple II's [[printed circuit board]] (PCB) underwent several revisions, as Steve Wozniak made modifications to it. The earliest version was known as Revision 0, and the first 6,000 units shipped used it. Later revisions added a "color killer" circuit to prevent color fringing when the computer was in text mode, as well as modifications to improve the reliability of cassette I/O. Revision 0 Apple IIs powered up in an undefined mode and had garbage on-screen, requiring the user to press Reset. This was eliminated in later board revisions. Revision 0 Apple IIs could display only four colors in hi-res mode, but Wozniak was able to increase this to six hi-res colors on later board revisions. (Technically it was eight, but only six were visible.<ref name="laboratorium.net">{{cite web | url=http://laboratorium.net/archive/2009/03/08/why_did_the_applie_ii_have_six_colors#comment-70109 | title=The Laboratorium : Why Did the Apple II Have Six Colors? }}</ref>)

Apple II PCBs have three [[random-access memory|RAM]] banks for a total of 24 RAM chips. Original Apple IIs had jumper switches to adjust RAM size, and RAM configurations could be 4, 8, 12, 16, 20, 24, 32, 36, or 48&nbsp;KiB. The three smallest memory configurations used 4kx1 [[Dynamic random-access memory|DRAMs]], with larger ones using 16kx1 DRAMs, or mix of 4-kilobyte and 16-kilobyte banks (the chips in any one bank have to be the same size). The early [[Apple II Plus|Apple II+]] models retained this feature, but after a drop in DRAM prices, Apple redesigned the circuit boards without the jumpers, so that only 16kx1 chips were supported. A few months later, they started shipping all machines with a full 48&nbsp;KiB complement of DRAM.

Unlike most machines, all [[integrated circuit]]s on the Apple II PCB were socketed; this cost more to manufacture and created the possibility of loose chips causing a system malfunction, but it was considered preferable to make servicing and replacement of bad chips easier.

The Apple II PCB lacks any means of generating an [[interrupt request]], although expansion cards may generate one. Program code had to stop everything to perform any [[Input/output|I/O]] task; like many of the computer's other idiosyncrasies, this was due to cost reasons and Steve Wozniak assuming interrupts were not needed for gaming or using the computer as a teaching tool.

==Display and graphics==
{{Main|Apple II graphics}}

Color on the Apple II series uses a quirk of the [[NTSC]] television signal standard, which made color display relatively easy and inexpensive to implement. The original NTSC television signal specification was black and white. Color was added later by adding a 3.58-megahertz subcarrier signal that was partially ignored by black-and-white TV sets. Color is encoded based on the [[phase (waves)|phase]] of this signal in relation to a reference [[color burst]] signal. The result is that the position, size, and intensity of a series of pulses define color information. These pulses can translate into [[pixel]]s on the computer screen, with the possibility of exploiting [[composite artifact colors]].

The Apple II display provides two pixels per subcarrier cycle. When the color burst reference signal is turned on and the computer is attached to a color display, it can display green by showing one alternating pattern of pixels, magenta with an opposite pattern of alternating pixels, and white by placing two pixels next to each other. Blue and orange are available by tweaking the pixel offset by half a pixel-width in relation to the color-burst signal. The high-resolution display offers more colors by compressing more (and narrower) pixels into each subcarrier cycle.

The coarse, low-resolution graphics display mode works differently, as it can output a pattern of dots per pixel to offer more color options. These patterns are stored in the character generator ROM, and replace the text character bit patterns when the computer is switched to low-res graphics mode. The text mode and low-res graphics mode use the same memory region and the same circuitry is used for both.

A single HGR page occupied 8&nbsp;KiB of RAM; in practice this meant that the user had to have at least 12&nbsp;KiB of total RAM to use HGR mode and 20&nbsp;KiB to use two pages. Early Apple II games from the 1977–79 period often ran only in text or low-resolution mode in order to support users with small memory configurations; HGR not being near universally supported by games until 1980.

==Sound==
Rather than a dedicated sound-synthesis chip, the Apple II contains a toggle circuit that can only emit a click through a built-in speaker or a line-out jack. More complex sounds, such as music or audio samples, are generated by software manually toggling the speaker at an appropriate frequency. This technique requires careful and precise timing, rendering it difficult to display moving graphics while sound is playing. Third party [[Apple II sound cards|expansion cards]] were later released that addressed this problem.

A similar technique is used for cassette storage: cassette output works the same as the speaker, and input uses a simple [[Zero crossing threshold detector|zero-crossing detector]] as a 1-bit audio digitizer. Routines in machine ROM encode and decode data in [[frequency-shift keying]] for the cassette.

==Programming languages==
{{More citations needed section|date=August 2022}}
Initially, the Apple II was shipped with Integer BASIC encoded in the motherboard [[read-only memory|ROM]] chips. Written by Wozniak, the interpreter enabled users to write software applications without needing to purchase additional development utilities. Written with game programmers and hobbyists in mind, the language only supported the encoding of numbers in 16-bit integer format. Since it only supported integers between -32768 and +32767 (signed 16-bit integer), it was less suitable to business software, and Apple soon received complaints from customers. Because Steve Wozniak was busy developing the Disk II hardware, he did not have time to modify Integer BASIC for floating point support. Apple instead licensed Microsoft's 6502 BASIC to create [[Applesoft BASIC]].

Disk users normally purchased a so-called Language Card, which had Applesoft in ROM, and was located below the Integer BASIC ROM in system memory. The user could switch between either BASIC by typing {{code|FP}} or {{code|INT}} in BASIC prompt. Apple also offered a different version of Applesoft for cassette users, which occupied low memory, and was started by using the {{code|LOAD}} command in Integer BASIC.

As shipped, Apple II incorporated a [[machine code monitor]] with commands for displaying and altering the computer's RAM, either one byte at a time, or in blocks of 256 bytes at once. This enabled programmers to write and debug machine code programs without further development software. The computer powers on into the monitor ROM, displaying a {{code|*}} prompt. From there, {{key press|Ctrl|B}} enters BASIC, or a machine language program can be loaded from cassette. Disk software can be booted with {{key press|Ctrl|P}} followed by {{key press|6}}, referring to Slot 6 which normally contained the Disk II controller.

A 6502 assembler was soon offered on disk,<ref>{{Cite book |last=Hyde |first=Randall |title=Using 6502 Assembly Language: How Anyone Can Program the Apple II |year=1981 |publisher=Datamost |isbn=9780881900033 |edition=1st}}</ref> and later the [[UCSD Pascal|UCSD compiler and operating system]] for the [[Pascal (programming language)|Pascal]] language were made available. The Pascal system requires a 16&nbsp;KiB RAM card to be installed in the language card position (expansion slot 0) in addition to the full 48&nbsp;KiB of motherboard memory.

==Manual==
The first 1,000 or so Apple IIs shipped in 1977 with a 68-page [[mimeograph]]ed "Apple II Mini Manual", hand-bound with brass paper fasteners. This was the basis for the ''Apple II Reference Manual,'' which became known as the Red Book for its red cover, published in January 1978. All existing customers who sent in their warranty cards were sent free copies of the Red Book. The ''Apple II Reference Manual'' contained the complete schematic of the entire computer's circuitry, and a complete source listing of the "Monitor" ROM firmware that served as the machine's [[BIOS]].

An Apple II manual signed by Steve Jobs in 1980 with the inscription "Julian, your generation is the first to grow up with computers. Go change the world." sold at auction for $787,484 in 2021.<ref>{{Cite news |title=An Apple II Manual Sells At Auction For $787,484 |language=en |work=NPR.org |url=https://www.npr.org/2021/08/23/1030223394/an-apple-ii-manual-sells-at-auction-for-787-484#:~:text=An%20Apple%20II%20Manual%20Sells%20At%20Auction%20For%20$787,484%20:%20NPR&text=An%20Apple%20II%20Manual%20Sells%20At%20Auction%20For%20$787,484%20The,owner%20of%20the%20Indianapolis%20Colts. |access-date=2022-09-04 |archive-date=September 4, 2022 |archive-url=https://web.archive.org/web/20220904120132/https://www.npr.org/2021/08/23/1030223394/an-apple-ii-manual-sells-at-auction-for-787-484#:~:text=An%20Apple%20II%20Manual%20Sells%20At%20Auction%20For%20$787,484%20:%20NPR&text=An%20Apple%20II%20Manual%20Sells%20At%20Auction%20For%20$787,484%20The,owner%20of%20the%20Indianapolis%20Colts. |url-status=live }}</ref>

==Operating system==
The original Apple II came with an 8&nbsp;KiB [[read-only memory|ROM]] containing a BASIC variant called [[Integer BASIC]] as well as a [[resident monitor]] called the Apple System Monitor. Initially, only [[magnetic-tape data storage|cassette tape]] was available for storage, which was considered too slow and unreliable for business use. In late 1977, Apple began to develop the [[Disk II]] floppy disk drive and required an operating system to utilize it. The existing standard at the time was [[CP/M]], but due to incompatibility with the 6502 processor and a perceived clunkiness, Apple contracted [[Shepardson Microsystems]] for $13,000 to write [[Apple DOS]].<ref name="Apple DOS commissioned">{{cite web|title=The untold story behind Apple's $13,000 operating system|url=http://news.cnet.com/8301-13579_3-57577597-37/the-untold-story-behind-apples-$13000-operating-system/|url-status=live|archive-url=https://web.archive.org/web/20130404095756/http://news.cnet.com/8301-13579_3-57577597-37/the-untold-story-behind-apples-$13000-operating-system/|archive-date=April 4, 2013|access-date=April 4, 2013|website=CNET|location=San Francisco, CA|df=mdy-all}}</ref><ref name="Apple DOS contract">{{cite web|title=DigiBarn Docs: "How Apple Booted Up" Key Documents in the Creation of Apple's First Operating System (Apple II DOS, 1978)|url=http://www.digibarn.com/collections/business-docs/apple-II-DOS/index.html|url-status=live|archive-url=https://web.archive.org/web/20130403083337/http://www.digibarn.com/collections///business-docs/apple-II-DOS/index.html|archive-date=April 3, 2013|access-date=April 4, 2013|publisher=DigiBarn|location=CA|df=mdy-all}}</ref> At Shepardson, Paul Laughton developed the software in just 35 days, a remarkably short deadline, even for the time.<ref name="Apple DOS developer">{{cite web|title=Apple Computer The Early Days A Personal Perspective|url=http://www.laughton.com/Apple/Apple.html|url-status=live|archive-url=https://web.archive.org/web/20130725020604/http://www.laughton.com/Apple/Apple.html|archive-date=July 25, 2013|access-date=April 4, 2013|publisher=Paul Laughton|df=mdy-all}}</ref> The Disk II and Apple DOS were released in late 1978. The final and most popular version of this software was [[Apple DOS]] 3.3.

Apple DOS was superseded by [[Apple ProDOS|ProDOS]], which supported a hierarchical filesystem and larger storage devices. With an optional third-party [[Zilog Z80|Z80]]-based [[expansion card]],<ref name="z80" /> the Apple II could boot into the [[CP/M]] operating system and run [[WordStar]], [[dBase|dBase II]], and other CP/M software.

Apple released [[Applesoft BASIC]] in 1977, a more advanced variant of the language which users could run instead of Integer BASIC for more capabilities, such as the ability to use [[floating point numbers]].

Some commercial Apple II software came on [[self-booting disk]]s and did not use standard DOS disk formats. This discouraged the copying or modifying of the software on the disks, and improved loading speed.

==Third-party devices and applications==
When the Apple II initially shipped in June 1977, no expansion cards were available for the slots. This meant that the user did not have any way of connecting a modem or a printer. One popular hack involved connecting a teletype machine to the cassette output.

Wozniak's [[open architecture|open-architecture]] design and Apple II's multiple expansion slots permitted a wide variety of third-party devices, including [[Apple II peripheral cards|peripheral cards]], such as [[Apple II serial cards|serial controllers]], display controllers, memory boards, hard disks, networking components, and [[Apple II system clocks|real-time clocks]]. There were plug-in [[Apple II processor cards|expansion cards]]—such as the [[Z-80 SoftCard]]—that permitted Apple II to use the [[Zilog Z80|Z80]] processor and run programs for the [[CP/M]] operating system,<ref name="z80">{{Cite magazine |last=Petersen |first=Marty |date=February 6, 1984 |title=Review: Premium Softcard IIe |magazine=[[InfoWorld]] |url=https://books.google.com/books?id=gC4EAAAAMBAJ&pg=PA64 |volume=6 |issue=6 |pages=64–66 |quote=Several manufacturers, however, make Z80 coprocessor boards that plug into the Apple II. |access-date=September 20, 2021 |archive-date=March 10, 2023 |archive-url=https://web.archive.org/web/20230310062207/https://books.google.com/books?id=gC4EAAAAMBAJ&pg=PA64 |url-status=live }}</ref> including the [[dBase|dBase II]] database and the [[WordStar]] word processor. The Z80 card also allowed the connection to a modem, and thereby to any networks that a user might have access to. In the early days, such networks were scarce. But they expanded significantly with the development of bulletin board systems in later years. There was also a third-party [[Motorola 6809|6809]] card that allowed [[OS-9]] Level One to be run. Third-party [[Apple II sound cards|sound cards]] greatly improved audio capabilities, allowing simple music synthesis and text-to-speech functions. [[Apple II accelerators|Apple II accelerator cards]] doubled or quadrupled the computer's speed.

Early Apple IIs were often sold with a [[Sup'R'Mod]], which allowed the composite video signal to be viewed in a television.

The Soviet Union radio-electronics industry designed Apple II-compatible computer [[Agat (computer)|Agat]]. Roughly 12,000 Agat 7 and 9 models were produced and they were widely used in Soviet schools.<ref>{{cite web | url=http://www.computer-museum.ru/histsoft/informatika_sorucom_2011.htm | title=Школьная информатика в России – техническая база начального периода | language=ru | access-date=February 1, 2019 | archive-date=September 23, 2015 | archive-url=https://web.archive.org/web/20150923210225/http://www.computer-museum.ru/histsoft/informatika_sorucom_2011.htm | url-status=live }}</ref> Agat 9 computers could run "Apple II" compatibility and native modes. "Apple II" mode allowed to run a wider variety of (presumably pirated) Apple II software, but at the expense of less RAM. Because of that Soviet developers preferred native mode over "Apple II" compatibility mode.

In 1978, Bob Bishop of [[Apple, Inc.|Apple Computer, Inc.]] programmed 9 Apple II computers to run the gameboard on the TV game show ''[[Tic-Tac-Dough]]'';.<ref>{{cite magazine|url=https://www.computingpioneers.com/index.php/Bob_Bishop |title=R&D on the Apple Frontier |last=Maginnis |first=Mike |date=June 2009 |magazine=[[Juiced.GS]] |pages=5&ndash;9|via=computingpioneers.com |access-date=April 15, 2024}}</ref>  Each Apple was responsible for displaying various contents for each box of the gameboard (category, X, O, bonus game numbers and amounts, TIC, TAC or Dragon, as well displaying custom messages and an active screensaver), and in turn controlled by an [[Altair 8800]] system. It was the first game show to use computerized graphics.<ref>{{Cite book | url=https://books.google.com/books?id=sMB1MHrE3oYC&q=Tic+Tac+Dough+first+game+show+computer&pg=PA327 | title=Who was Who on TV| isbn=9781456824563| last1=Chance| first1=Norman| date=2011-01-07| publisher=Xlibris Corporation}}</ref>

==Reception==
[[File:Apple II advertisement Dec 1977 page 2.jpg|thumb|Advertisement for Apple II (1977)]]
Jesse Adams Stein wrote, "As the first company to release a 'consumer appliance' micro-computer, Apple Computer offers us a clear view of this shift from a ''machine'' to an ''appliance''." But the company also had "to negotiate the attitudes of its potential buyers, bearing in mind social anxieties about the uptake of new technologies in multiple contexts. The office, the home and the 'office-in-the-home' were implicated in these changing spheres of gender stereotypes and technological development."<ref>{{Cite magazine |last=Stein |first=Jesse Adams |year=2011 |title=In Memoriam: Domesticity, Gender and the 1977 Apple II Personal Computer |magazine=Design and Culture |volume=3 |issue=2 |page=194}}</ref> After seeing a crude, [[wire-wrapped]] prototype demonstrated by Wozniak and [[Steve Jobs]] in November 1976,<ref name="helmers197803">{{Cite magazine |last=Helmers |first=Carl |date=March 1978 |title=An Apple to Byte |pages=18 |magazine=[[Byte (magazine)|BYTE]] |volume=3 | issue=3 |url=https://archive.org/stream/byte-magazine-1978-03/1978_03_BYTE_03-03_Computer_Music_Systems#page/n19/mode/2up |access-date=October 17, 2013}}</ref> ''Byte'' predicted in April 1977, that the Apple II "may be the first product to fully qualify as the 'appliance computer' ... a completed system which is purchased off the retail shelf, taken home, plugged in and used". The computer's color graphics capability especially impressed the magazine.<ref name="helmers197704">{{Cite magazine |last=Helmers |first=Carl |date=April 1977 |title=A Nybble on the Apple |pages=10 |magazine=[[Byte (magazine)|BYTE]] | volume=2 | issue=4 |url=https://archive.org/stream/byte-magazine-1977-04/1977_04_BYTE_02-04_Baudot_Machines#page/n11/mode/2up |access-date=October 16, 2013}}</ref> The magazine published a favorable review of the computer in March 1978, concluding: "For the user that wants color graphics, the Apple II is the only practical choice available in the 'appliance' computer class."<ref name="helmers197803" />

''[[Personal Computer World]]'' in August 1978 also cited the color capability as a strength, stating that "the prime reason that anyone buys an Apple II must surely be for the colour graphics". While mentioning the "oddity" of the artifact colors that produced output "that is not always what one wishes to do", it noted that "no-one has colour graphics like this at this sort of price". The magazine praised the sophisticated monitor software, user expandability, and comprehensive documentation. The author concluded that "the Apple II is a very promising machine" which "would be even more of a temptation were its price slightly lower ... for the moment, colour is an Apple II".<ref name="pcw197808">{{Cite magazine |last1=Coll |first1=John |last2=Sweeten |first2=Charles |date=August 1978 |title=Colour is an Apple II |pages=50 |magazine=Personal Computer World |url=https://archive.org/stream/Personal_Computer_World_1978-08_Apple_II_Review#page/n0/mode/2up |access-date=18 August 2014}}</ref>

Although it sold well from the launch, the initial market was to hobbyists and computer enthusiasts. Sales expanded exponentially into the business and professional market, when the spreadsheet program [[VisiCalc]] was launched in mid-1979. VisiCalc is credited as the defining [[killer app]] in the microcomputer industry.

By the end of 1977 Apple had sales of {{US$|long=no|775,000}} for the fiscal year, which included sales of the Apple I. This put Apple clearly behind the others of the "holy trinity" of the TRS-80 and Commodore PET, even though the TRS-80 was launched last of the three.<ref>{{Cite book |last=Badgnall |first=Brian |title=Commodore |date=May 24, 2024 |publisher=Variant Press |isbn=978-0973864960}}</ref> However, during the first five years of operations, revenues doubled about every four months. Between September 1977 and September 1980, annual sales grew from {{US$|long=no|775,000}} to {{US$|long=no|118 million}}.<ref>{{Cite book |last=Malone |first=Michael S. |title=Infinite Loop |date=1999 |publisher=Doubleday Business |isbn=0-385-48684-7 |page=157}}</ref> During this period the sole products of the company were the Apple II and its peripherals, accessories, and software.

In 2006, PC World wrote that the Apple II was the greatest PC of all time.<ref>{{Cite web|url=http://www.pcworld.com/article/id,126692-page,10-c,systems/article.html#II|title=The 25 Greatest PCs of All Time|archive-url=https://web.archive.org/web/20080511194506/http://www.pcworld.com/article/id,126692-page,10-c,systems/article.html#II |archive-date=May 11, 2008 }}</ref>

==References==
{{Reflist}}

==External links==
{{commons category|Apple II}}
* [http://bitsavers.informatik.uni-stuttgart.de/pdf/apple/apple_II/ Additional documentation in Bitsavers PDF Document archive]
* [https://www.old-computers.com/museum/computer.asp?c=68&st=1 Apple II on Old-computers.com]
* [https://sites.google.com/a/my.sduhsd.net/apple-ii-resource/ Online Apple II Resource]
* [http://apple2history.org/appendix/ahb/ahb2 Apple2History.org]
* [https://www.youtube.com/watch?v=VStscvYLYLs <nowiki>How the Apple ][ Works!</nowiki>] – on YouTube by the [[The 8-Bit Guy|8-Bit Guy]]

{{Apple hardware before 1998}}
{{Steve Wozniak}}
{{Authority control}}

[[Category:Apple II computers]]
[[Category:Computer-related introductions in 1977]]
[[Category:6502-based home computers]]
[[Category:8-bit computers]]
[[Category:Products and services discontinued in 1979]]
[[Category:1977 establishments in the United States]]
[[Category:1979 disestablishments in the United States]]

[[ca:Apple II]]