Apple II
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Wikipedia-Article "Apple II"
The Apple II family was the first series of microcomputers mass produced by Apple Computer, in the late 1970s through to the early 1990s. Completely different from Apple's later Macintosh computers, the Apple II was a predominantly 8-bit architecture based on the 6502-series microprocessor.
The progenitor was the Apple I, which was a hand-built machine sold to hobbyists. It was never produced in quantity, but pioneered many of the features that would make the Apple II a success. The first large-scale production computer was the Apple II. It became popular with home users, as well as occasionally being sold to business users, particularly after the release of the first ever spreadsheet on any computer, VisiCalc. See the computing timeline for dates of Apple II family model releases – the 1977 Apple II and its younger siblings, the II Plus, IIe, IIc and IIGS.
The "II" portion of the name was alternately rendered in a variety of creative ways using punctuation symbols. For example, the II and the "unenhanced" IIe was most commonly written ][ and ][e, and the IIc and enhanced, platinum IIe models were written as //c, and //e. Finally, the IIgs and IIc plus were rendered in the form used in this article.
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History
The original Apple II
The first Apple II computers went on sale on June 5, 1977 with a MOS Technology 6502 microprocessor running at 1 MHz, 4 KB of RAM, an audio cassette interface, and the Integer BASIC programming language built into the ROMs. The video controller displayed 24 lines by 40 columns of upper-case-only text on the screen, with NTSC composite video output for display on a monitor, or on a TV set by way of an RF modulator. Third-party add-on cards were available for 80-column and lower-case support. Users could save and retrieve programs and data on audio cassettes; other programming languages, games, applications and other software were available on cassette too. The original retail price was $1298 with 4KB of RAM and $2638 with 48KB of RAM.
Later, an external 5¼-inch floppy disk drive, the Disk II, with controller card that plugged into one of the computer's slots (usually slot #6), enabled much more convenient data storage and retrieval. This disk drive interface created by Steve Wozniak (Woz) is still regarded as an engineering masterpiece. Where other controllers had dozens of chips for synchronizing data I/O with disk rotation, seeking the head to the appropriate track, and encoding the data into magnetic pulses, Woz's controller card had few chips; instead, the Apple DOS used software to perform the functions. The controller also used a form of Group Code Recording, which was simpler and easier to implement in software than the more common MFM. According to legend, Woz laid out the circuit board several times as he realized that moving one more function to software would allow him to remove another chip. In the end, the low chip count of the controller contributed to making Apple's Disk II the first affordable floppy drive system for personal computers. As a side effect, Woz's scheme also made it easy for proprietary software developers to make the media on which their applications shipped hard to copy by employing tricks such as changing the low-level sector format or stepping the drive's head between the tracks; however, other companies eventually sold software such as Copy II Plus and Locksmith that could foil such protection.
The approach taken in the Disk II controller was typical of Woz's design sensibility. The Apple II is full of clever engineering tricks to save hardware and reduce costs. For example, by interleaving the video generation circuitry's memory access with the CPU's, Woz eliminated the need for a separate refresh circuit for the DRAM chips. Rather than using a complex analog-to-digital circuit to read the outputs of the game controller, Woz used a simple timer circuit whose period was proportional to the resistance of the game controller, then used a software loop to measure the timer. The text and graphics screens had a frankly Byzantine arrangement (the scanlines were not stored in sequential areas of memory) which reputedly was due to Woz's realization that doing it that way would save a chip; it was less expensive to have software calculate or look up the address of the needed scanline than to include the extra hardware. The epitome of this design philosophy was the Apple II sound circuitry. Rather than having a dedicated sound synthesis chip, the Apple II had a toggle circuit that could only emit a click through a built-in speaker; all other sounds (including two, three, and eventually four-voice music and even playback of audio samples and speech synthesis) were generated entirely by very clever software that clicked the speaker at the right times. Not for nearly a decade would an Apple II be released with dedicated sound chip. These brilliant quirks served as a gauntlet that drew scores of equally quirky and brilliant programmers to the platform, and these became the Apple II's lifeblood. Wozniak's open design and the Apple's multiple expansion slots permitted a wide variety of third-party devices to expand the capabilities of the machine. Serial controllers, improved display controllers, memory boards, hard disks, and networking components were available for this system in its day. There were also emulator cards, such as the Z80 card which permitted the Apple to switch to the Z80 processor and run a multitude of programs developed under the CP/M operating system such as the dBase II database and the WordStar word processing program. There was also a third-party 6809 card with which one could run OS-9 Level One. The Mockingboard sound card greatly improved the audio capabilities of the Apple with simple music synthesis and text to speech. Eventually accelerator boards were created to double or quadruple the computer's speed.
The family grows
![The Apple II Plus, with original Disk ][ 5.25 drives](http://en.wikipedia.org/wiki/Image:Apple_II_Plus.jpg)
The Apple II was eventually superseded by the Apple II Plus, which 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 (albeit at a slower speed than Steve Wozniak's Integer BASIC) and became the standard BASIC dialect on the Apple.
The Apple II Plus had a total of 48 kilobytes 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 microprocessor could support a maximum of 64 KB of memory, and a machine with 48 KB RAM reached this limit because the machine had an additional 16 KB of read-only memory. 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 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 was followed in 1983 by the Apple IIe, a cost-reduced yet more powerful machine that used newer chips to reduce the component count and add new features, such as the display of upper and lowercase letters and a standard 64 KB of RAM. The IIe RAM was configured as if it were a 48K Apple II Plus with a language card; the machine had no slot 0, but instead had an auxiliary slot that for all practical purposes took the place of slot 3. The auxiliary slot could accept a 1K memory card to enable the 80-column display (the card contained only RAM; the hardware and firmware for the 80-column display was built into the Apple IIe). An "extended 80-column card" with more memory expanded the machine's RAM to 128 KB. As with the language card, the memory in the 80-column card was bank-switched over the machine's main RAM; this made the memory better suited to data storage than to running software, and in fact the ProDOS operating system, which was introduced with the Apple IIe, would automatically configure this memory as a RAM disk upon booting. Third-party aux-slot memory cards later allowed expansion up to 1 MB. The extended 80-column card also enabled two new graphics modes, Double Hi-Res and Double Lo-Res, which doubled the horizontal resolution and, in the case of Double Hi-Res, doubled the number of available colors as well over the standard hi-res mode.
The IIe was the most popular Apple II ever built and was widely considered the "workhorse" of the line. It also has the distinction of being the longest-lived Apple computer of all time -- it was manufactured and sold with only minor changes for nearly eleven years.
Two and a half years before the Apple IIe, Apple produced and marketed a computer called the Apple III for business users. This product was not a success, and Steve Wozniak has been quoted as saying that the Apple III had a 100% failure rate -- every single machine manufactured had some kind of fault. Many of its features were carried over in the design of the Apple IIe, though, including the ProDOS operating system, which was based on Apple III SOS.
Apple released the Apple IIc in May 1984, billing it as a portable Apple II. (By portable it was meant that the computer could be easily carried from place to place; lacking battery power and a built-in display, it was not a true portable as we would use the term today.) The IIc was essentially a Apple IIe with extended 80-column card in a compact, notebook-sized form factor; it even sported a carrying handle that folded down to prop the machine up in a typing position.
The Apple IIc was the first Apple II to use the updated 65C02 processor, and featured a built-in floppy drive and 128K RAM, with a built-in disk controller that could control external drives, both NTSC or PAL and digital RGB video interfaces, serial interfaces for modem and printer, a joystick/mouse port. Having all these interfaces built-in was good because the Apple IIc, unlike previous Apple II models, had no internal expansion slots at all, although third parties did eventually figure out how to wedge up to 1 MB of additional memory and a real-time clock into the machine. To play up the portability, two different monochrome LCD displays were sold for use with the IIc, although both were short-lived due to a high cost and poor legibility. (A IIc with the smaller of these displays appeared briefly in the film 2010.) The IIc had an external power supply that converted AC power to 12V DC, allowing third parties to offer battery packs and automobile power adapters that connected in place of the supplied AC adapter.
On the heels of the Apple IIc, Apple introduced the Enhanced Apple IIe, along with an upgrade kit for existing IIe machines, that included an updated 65C02 processor and provided many of the firmware enhancements from the IIc, including MouseText, an alternate character set that contained a variety of icons and graphical widgets in the text display mode. A final version of the IIe, known as the Platinum Apple IIe, was introduced later; it added a numeric keypad and made an extended 80-column card (and thus 128 KB RAM) standard and updated the color of case to match the then-standard Apple light-gray color scheme.
The next member of the line was the Apple IIGS computer, released in 1986. A radical departure from the existing Apple II line, the IIGS featured a true 16-bit microprocessor, the 65C816, operating at 2.8 MHz with 24-bit addressing, allowing expansion up to 8 MB of RAM without the bank-switching hassles of the earlier machines. It sported two completely new graphic modes sporting a palette of 4,096 colors; however, only 4, 16, or 256 colors could be used at a time, depending on the mode and other restrictions. In a departure from earlier Apple II graphics modes, the new modes laid out the scanlines sequentially in memory. However, programmers in search of a graphics challenge could always turn to 3200-color mode, which involved precisely swapping out the color palettes as the monitor's electron beam traced the screen, allowing up to sixteen different colors for each of 200 scanlines. This technique did not leave many CPU cycles available for other processing, so this "mode" was best suited to displaying static images.
The Apple IIGS stood out from any previous (or future) Apple II model, evolving and advancing the platform into the next generation of computing while still maintaining near-complete backward compatibility. The secret of the Apple IIGS's compatibility was a single chip called the Mega II, which contained the functional equivalent of an entire Apple IIe computer (sans processor), which, combined with the flawless 65C02 emulation mode of the 65C816 processor, provided full support for legacy software.
The computer also included a 32-voice Ensoniq synthesizer with 64K dedicated RAM, 256K of standard RAM, built-in peripherals port (switchable between IIe-style card slots and IIc-style onboard controllers for disk drives, mouse, and serial devices), built-in AppleTalk networking, and a ROM toolkit that supported a graphical user interface derived from Mac OS. The computer could run existing 8-bit Apple II software (including software written for the very first Apple II in Integer BASIC), but also supported new 16-bit Macintosh-style software running under a new OS (first called ProDOS 16 and later called GS/OS). This included a Finder that could be used for managing disks and files and opening documents and applications, along with desk accessories -- just like the Macintosh. The 16-bit operating system would automatically switch to the text display and downshift to 8-bit mode to run legacy software. Eventually the IIGS even gained the ability to read and write Macintosh disks and, through third-party software, even multitasking of a sort and outline font support.
A slightly revised IIGS model, the Apple IIGS with 1 Megabyte of RAM (better known as the "ROM 03"), was introduced in late 1989 with additional built-in memory, improvements to the firmware, and cleaner sound output. Most users considered it a minor maintaince update rather than a new machine.
The final Apple II model was the Apple IIc Plus introduced in 1988. It was the same size and shape as the IIc that came before it, but the 5¼" floppy drive had been replaced with a 3½" drive, the power supply was moved inside (gone was the IIc's "brick on a leash" power supply), and the processor was a fast 4MHz 65C02 processor that actually ran 8-bit Apple II software faster than the IIGS. (Third-party accelerators for other models could, however, go as fast as 10MHz, and IIGS accelerators would eventually reach 16MHz.) The IIc Plus's accelerator was derived from a design licensed from Zip Technologies, a third-party maker of accelerators for the Apple II, though Apple used two chips instead of combining the processor and supporting logic on a single chips as did Zip. The IIc Plus also featured a new keyboard layout that matched the Platinum IIe and IIGS. Many perceived the IIc Plus as Apple's attempt to compete with the Laser 128EX/2, a popular third party Apple-compatible machine that also had an accelerated processor and a built-in 3½" drive. There were few other rational explanations for Apple expending resources on the continued development of a new 8-bit Apple II model rather than furthering the 16-bit Apple IIGS.
In 1990 the Apple IIe Card, an expansion card for the LC line of Macintosh computers, was released. Essentially a miniaturized Apple IIe computer on a card (utilizing the Mega II chip from the Apple IIGS), this card allowed the Macintosh to run 8-bit Apple IIe software through hardware emulation (although video was emulated in software and was slower at times than a IIe). Many of the LC's built-in Macintosh peripherals could be "borrowed" by the card when in Apple II mode (i.e. extra RAM, 3½ floppy, AppleTalk networking, hard disk). The IIe card could not, however, run software intended for the 16-bit Apple IIGS. The Macintosh LC with IIe Card was intended to replace the Apple IIGS in schools and homes and was presumably the reason a new model Apple IIGS that was confirmed by insiders to be in development at one point was cancelled and never released.
Apple's Macintosh product line eclipsed Apple II sales in the early 90's -- after Apple invested years of Apple II profits into the newer computer line. Even after the introduction of the Macintosh, the Apple II had remained Apple's primary source of revenue for years. Once the Apple II and its associated community of third-party developers and retailers was a billion-dollar-a-year industry. Apple continued to sell the IIGS until 1993 and continued to sell the Platinum IIe into 1996. The Nintendo and Super Nintendo game systems were based on the 6502 and 65816 processors, respectively, and the wide range of assembly development tools for the Apple IIe and IIGS made them ideal platforms for game development for these systems.
Clones
Like the IBM PC, the Apple II was frequently cloned, both in the United States and abroad. According to some sources (see below), there were more than 190 different models of Apple II clones were manufactured. Many of these had "fruit" names (e.g. "Pineapple") to indicate to the initiated that they were Apple II clones. For many years the most widely-used microcomputer in the Soviet Union and in Eastern Europe was the Agat, a Russian Apple II clone with a Cyrillic character set.
The Ace clones from Franklin Computer Corporation are the best known and had the most lasting impact, as Franklin copied Apple's ROMs and software and freely admitted to doing so. Franklin's argument: a computer's ROM was simply a pattern of switches locked into a fixed position, and one cannot copyright a pattern of switches. Apple fought Franklin in court for about five years to get its clones off the market, and was ultimately successful. The company later released non-infringing but less-compatible clones; these could run ProDOS and AppleWorks and had an Applesoft-like BASIC, but compatibility with other software was hit-or-miss.
Apple also challenged VTech's Laser 128, an enhanced clone of the Apple IIc first released in 1984, in court. This legal challenge proved unsuccessful, because VTech had reverse-engineered the Monitor ROM rather than copying it and had licensed the Applesoft ROM from its creator, Microsoft. Incredibly, Apple had neglected to obtain exclusive rights to the Applesoft dialect of BASIC from Microsoft; just as incredibly, VTech was the first cloner to bother licensing it. The Laser 128 proved popular and remained on the market for many years, both in its original form and in enhanced versions that ran faster than 1 MHz. Although it wasn't 100% compatible with the Apple II, it was close, and its popularity ensured that most developers tested their software on a Laser as well on as genuine Apple machines. Because it was frequently sold via mail order and mass-market retailers such as Sears, the Laser 128 may have cut into the sales of low-cost competitors such as Commodore Business Machines as much as it did Apple's.
While the first Apple II clones were generally exact copies of their Apple counterparts that competed mainly on price, later clones tended to have extra capabilities too. A Franklin model, the Ace 1000, sported a numeric keypad and lower-case long before these features were added to the Apple II line. The Laser 128 series is sometimes credited with spurring Apple to release the Apple IIc Plus; the built-in 3.5" drive and accelerated processor were features Laser had pioneered.
Bell & Howell, an audiovisual equipment manufacturer whose equipment (particularly film projectors) was ubiquitous in schools, offered what appeared at first glance to be Apple II Plus clones in a distinctive black plastic case. However, these were genuine Apple products manufactured exclusively for B&H for a short period of time. Many schools had a few of these "black Apples" in their labs.
Apple II media
The Disk II floppy drive used 5¼-inch floppy disks. The first disk operating systems for the Apple II were DOS 3.1 and DOS 3.2, which stored 113.75 KiB on each disk. After about two years, DOS 3.3 was introduced, storing 140 KiB thanks to a minor hardware change on the disk controller. The user community discontinued use of DOS 3.2 except for running legacy software. A program called MUFFIN was provided with DOS 3.3 to allow users to copy files from DOS 3.2 disks to DOS 3.3 disks.
A DOS 3.3 disk was formatted with 35 tracks of data; each track contained 16 sectors (DOS 3.2 only had 13 sectors), and each sector stored 256 bytes of data. Tracks 0, 1, and most of track 2 were reserved to store DOS 3.3 itself, and track 17 was reserved for the directory (track 17 was chosen because it was located in the middle of the 35-track disk to reduce the average seek time to the frequently-used directory track.)
Most game publishers did not include DOS 3.3 on their floppy disks; they wrote their own boot loaders and read-only file systems to consume a minimum amount of space on disk and to discourage "crackers" from snooping around in the game's copy-protection code.
Some manufacturers shipped floppy drives that could write 40 tracks to most 5¼-inch disks, yielding 160 KiB of storage per disk, but the format did not catch on widely, and no known software was published on 40-track media.
Later Apple IIs could use 3½-inch disks with a total capacity of 800 KB. DOS 3.3 did not support these drives natively; third-party software was required, and disks larger than about 400 KB had to be split up into multiple "virtual disk volumes." ProDOS, a 1983 descendent of the Apple ///'s SOS, quickly became the Apple II operating system of choice thanks to its native support of volumes up to 32 MB in size (and the fact that AppleWorks required it). Less common in the early days were Apple II computers outfitted with an Apple Profile hard drive, which had a total capacity of 5 MiB. Later, Apple and other companies introduced SCSI and IDE interface cards and larger hard drives; a popular early third-party model was the Sider, from First Class Peripherals, which offered 10 MB for a then-incredible $695.
Life after death
Today, even a PC running Microsoft Windows can emulate the important Apple II models with emulator software such as AppleWin by copying the disk through a serial line. However, emulators cannot run software on copy-protected media unless somebody "cracks," or removes the copy restrictions from, the software. Numerous disk images for Apple II software are available free over the Internet. The Lost Classics Project had as its goal to convince the copyright holders of classic Apple II software to officially allow unrestricted free distribution of their software and has "freed" a number of programs.
One unusual homage to the Apple II is an XScreenSaver "hack" named bsod. The bsod screensaver duplicates the appearance of computer crash screens for various operating systems (including the Windows Blue Screen of Death, after which it is named). In the case of the Apple II, the screensaver actually emulates the CRT display typically used with the computer, so the screen will appear to twitch as text blocks turn on and off, a common quirk of analog NTSC displays. Another module called "Apple2" shows a working Apple II being used to type and run three different BASIC programs, also with CRT emulation and even typos (or "syntax errors").
Industry impact
It is difficult to estimate the enormous impact that the Apple II family of computers has had on world business and, especially, the technology industry. The Apple II was the first computer many people ever saw, and it was affordable enough for middle-class families. Its popularity bootstrapped the entire computer game and the educational software markets and began a boom in the word processor and computer printer markets. The first microcomputer "killer app" for business was VisiCalc, the first spreadsheet, and it ran first on the Apple II; many businesses bought Apple IIs just to run VisiCalc. Apple's success in the home market inspired competitive home computers such as the VIC-20 (1980) and Commodore 64 (1982), which through their significantly lower price point introduced computers to several million more home users -- grabbing some of Apple's market share in the process.
The success of the Apple II in business spurred IBM to create the IBM PC, which was then purchased by middle managers in all lines of business in order to run spreadsheet and word processor software, at first ported from Apple II versions; later, whole new application software dynasties would be founded on the PC. The popularity of these PCs and their clones then transformed business again with LAN applications such as e-mail and later Internet applications such as Usenet and the WWW.
One valuable lesson from the Apple II was the importance of an open architecture to the success of a computer platform. The first Apple IIs shipped with a schematic of the entire computer's circuitry and a complete source listing of the "Monitor" ROM software that served as the machine's BIOS, along with a detailed technical manual. The Apple II's slots, allowing any peripheral card to take control of the bus, enabled an independent industry of card manufacturers who together created a flood of hardware products that let users build systems that were far more powerful and useful (at a lower cost) than any competing system, most of which were not nearly as expandable and were universally proprietary. Even the game port was unusually powerful and could be used for digital and analog input and output; one hacker used it to drive a LaserWriter printer.
Apple decided not to create an open architecture with the initial Macintosh models, and this is widely seen as having hobbled its success. Meanwhile, IBM had created its IBM PC with an open architecture, which resulted in the near-universal adoption of the platform but led to a Pyrrhic victory for IBM itself. In the end, its off-the-shelf, open architecture allowed clones to be manufactured by startup competitors such as Compaq, Dell, Gateway, and countless others, leading eventually to IBM's abandonment of the personal computer business in 2005.
See also
- List of Apple II games
- List of Apple II application software
- Publications/Periodicals devoted to the Apple II
- Apple III
- List of BBS software – For the Apple II and other machines
References
- Wozniak, Steve. "System Description: The Apple II". BYTE. May 1977. [1]