The Apple II was shown at the first West Coast Computer Faire in April 1977, and the first complete system shipped on 10 June. It cost $1,298 with 4K of memory, or $2,638 with the full 48K, and it came assembled in a plastic case with a keyboard, BASIC in ROM, game paddles and colour graphics. The month before it shipped, its designer, Steve Wozniak, explained in BYTE how he had made one small board do all of that. The answer, again and again, was to make one circuit do two jobs.
A history of the company published in 1990 by the British user group Apple 2000 counts about 570 Apple IIs sold in the year to September 1977, about 7,600 the following year, 35,100 the year after, and 78,100 in the year to September 1980. The two millionth Apple II was sold in November 1984. In April 1990 Apple’s head, John Sculley, told user groups that “there are 6 million Apple IIs” and that “it would be unfair to walk away from that”. The last model, the Apple IIe, was discontinued in November 1993.
Fast facts
- Manufacturer: Apple Computer, Cupertino, California.
- Shown: West Coast Computer Faire, April 1977; first systems shipped 10 June 1977.
- CPU: MOS 6502 at 1.023 MHz, by Apple’s figure.
- RAM: 4K to 48K on the board, using 4K or 16K chips.
- ROM: 8K, with Wozniak’s BASIC (later called Integer BASIC) and a monitor.
- Text: 40×24, upper case only.
- Graphics: 40×48 blocks in 16 colours; 280×192 high resolution in four colours on the first boards and six on later ones.
- Sound: a speaker that clicks each time a program touches one address.
- Expansion: eight slots.
- Storage: cassette at about 1,500 bits a second; the Disk II floppy drive from 1978.
- Price: $1,298 (4K) to $2,638 (48K), or $598 for the bare board.
One circuit, two jobs
Wozniak’s BYTE article of May 1977 is a first-hand account of the design, and it keeps pointing at the circuits that are not there.
The display refreshes the memory. Dynamic RAM forgets unless something walks through its addresses and recharges the cells, and most designs added logic to do it. The Apple’s display circuit already reads memory continuously to draw the screen. Wozniak split every processor cycle in two, giving the first half, when the 6502 is busy inside itself, to the video circuit: “Since all of memory is continuously being scanned by the low order bits out of video generator, the entire 48 K byte field (maximum) of dynamic memory is refreshed by the video portion of the cycle.” The processor never waits for the screen, and the refresh comes, as he put it, “for free”.
The clock serves the television. Every timing signal comes from one 14.318 MHz crystal, four times the NTSC colour frequency. Jim Sather’s 1983 study of the hardware found the cost of that choice: to keep the picture’s colour in step, one processor cycle in every 65 is stretched. The 6502 runs at 1.0227 MHz for 64 cycles and more slowly for the “long cycle”, so it really averages 1.0205 MHz.
Cassette and slots. The tape interface was simple and quick for its day. Wozniak wrote that it “averages over 180 bytes per second”, using one cycle of 2,000 Hz for a zero and one cycle of 1,000 Hz for a one. Eight expansion slots sat along the back of the board, and they are why the Apple II could take disk drives, printer interfaces and extra cards without a new model.
Colour from position
The Apple II has no colour registers in high-resolution mode. It stores only whether each dot is on or off, and the colour comes from where the dot falls against the television’s colour signal. Apple’s 1979 Reference Manual spells out the rules. Seven bits of each byte are dots, 40 bytes make the 280 dots of a line, and there are 192 lines. A lit dot in an even column shows as violet, one in an odd column as green, and two lit side by side show as white. The eighth bit of each byte shifts that byte’s dots by half a dot, which turns violet and green into blue and red (usually seen as orange).
Wozniak’s first boards did not have the shift, and his May 1977 article lists only “black, white, violet and green”. The manual notes that “On Revision 0 Apple boards, the colors red and blue are unavailable”. Later boards gave six colours, with rules attached: dots in the same byte must all come from one colour set, so violet and orange cannot sit in the same seven-dot group.
Sather summed up the trade in 1983: “There is no need to store HIRES color information in memory. The color information is part of dot positioning. Dot position determines color. Think of the savings in memory over a system where the color information of dots is stored as separate intelligence. The flip side of this coin is: think of the elaborate programs required to produce colored displays dependent on dot position.” Every Apple II game with coloured graphics was written around those rules.
Low resolution is simpler: 40×48 blocks, each four bits, in 16 colours. Apple’s first advertisements said 15, and Sather’s analysis shows why: two of the sixteen, the greys, are identical.
The Disk II and VisiCalc
The Disk II came in the summer of 1978. Apple’s advertisement in BYTE that August offered a 5¼-inch drive with its controller card and disk operating system for $495, storing 113K per diskette and able to “load, store and run any file by name”. DOS 3.3 in 1980 raised the capacity to over 142K. Apple built its millionth Disk II in January 1983.
The disk made the Apple II a business machine. In September 1979 Personal Software advertised VisiCalc in BYTE: an “electronic ‘sheet of paper’” on which changing one figure updated every other figure that depended on it. It was “available now for Apple II computers”, cost $99.50, and needed “a 32k disk system”. The advertisement also said: “You might find that VisiCalc alone is reason enough to own a personal computer.” Dan Bricklin had the idea while watching a professor recalculate a budget on a blackboard at Harvard Business School, and wrote it with Robert Frankston. Looking back in 1985, Compute! said it “was so useful that it helped sell Apple computers”.
Schools and games
Apple formed the Apple Education Foundation in July 1979, and by March 1980 it was awarding computers to people developing teaching materials. Between May and September 1983 Apple’s “Kids Can’t Wait” programme gave about 9,000 computers to California schools, each supplied with Apple Logo.
Games were written around the hardware’s rules. In Computer Gaming World’s reader ratings of July 1983, Sir-Tech’s Wizardry came top, and most of the list was Apple games. Richard Garriott’s Ultima (1981) and Doug Smith’s Lode Runner (1983) began on the Apple II. Jordan Mechner’s Karateka was on sale for the Apple and the C64 by 1985, and his Prince of Persia was still on sale to Apple II owners in 1990.
The family
- Apple II Plus (1979): Applesoft II BASIC in ROM “in lieu of Apple Integer BASIC”, and a monitor that started the machine by itself. Apple’s 1979 Reference Manual covers both machines.
- Apple IIe (1983): a keyboard with upper and lower case, 64K of RAM and an 80-column text option.
- Apple IIc (1984): a compact machine with the disk drive built in, launched in San Francisco on 24 April 1984, when dealers placed more than 52,000 orders. The IIc Plus replaced it in 1988.
- Apple IIGS (1986): a 16-bit model built around the 65C816, which could still run the older machines’ programs. Your Computer reported it in October 1986 as a machine with 256K, expandable to 8MB, and full Apple II compatibility.
Sources
- Stephen Wozniak, “System Description: The Apple-II”, BYTE, vol. 2 no. 5, May 1977, pp. 34-43: video and refresh (p. 35), high-resolution colours and mixed mode (p. 39), cassette rate, recording scheme and eight slots (p. 40).
- BYTE, vol. 2 no. 7, July 1977, pp. 22-23: Apple advertisement and price list.
- Apple Computer, Apple II Reference Manual (1979): high-resolution graphics and colours (p. 19), the Revision 0 limitation, the speaker, low-resolution colours, the 1.023 MHz clock and the half-dot delay (p. 97); the manual covers the Apple II and Apple II Plus.
- Jim Sather, Understanding the Apple II (Quality Software, 1983): timing and the long cycle (p. 3-4); colour generation (pp. 8-6, 8-7).
- BYTE, vol. 3 no. 8, August 1978, p. 15: Apple advertisement introducing Disk II at $495, 113K per diskette.
- BYTE, vol. 4 no. 9, September 1979, p. 51: Personal Software advertisement for VisiCalc.
- Apple 2000, Souvenir Issue 1980-1990 (1990), Apple history timeline: the West Coast Computer Faire, first shipment, fiscal-year sales, the Apple Education Foundation, DOS 3.3, the millionth Disk II, “Kids Can’t Wait”, the IIc launch, the two millionth Apple II and the IIc Plus.
- Antic, vol. 2 no. 12, March 1984: Apple Logo supplied with the “Kids Can’t Wait” computers.
- William G. Watson, report of John Sculley’s address to the Apple User Group Advisory Council, San Jose, 16 April 1990, Apple 2000, vol. 5 no. 5, October 1990.
- Computer Gaming World, no. 11, July 1983: reader game ratings, Wizardry first at 8.09.
- Computer Gaming World, June 1985: Karateka (Broderbund) for Apple and C64.
- Ultima player reference card (1981), Apple II edition.
- Apple 2000, vol. 5 no. 5, October 1990: dealer list including Prince of Persia (Broderbund).
- Your Computer, October 1986: news report of the Apple IIGS.
- Compute!, vol. 7 no. 59, April 1985: Bricklin, Frankston and the origin of VisiCalc.
- Apple Computer, Apple IIe Technical Reference Manual: keyboard, 64K RAM and 80-column display.
- Apple IIe, Wikipedia: discontinued 15 November 1993. (web, secondary)