In 1975 BYTE introduced a new processor from a Pennsylvania calculator firm under the headline “Son of Motorola, or, the $20 CPU Chip”. The chip was MOS Technology’s 6501, and it plugged straight into a socket designed for Motorola’s 6800. Its designers had worked on the 6800 until the year before. Motorola went to court, and the 6501 disappeared, but its sibling, the 6502, went on to run the Apple II, the Atari 400 and 800 and the Commodore 64.
That episode is one reason Motorola matters to anyone programming the machines of the period. The other is the 68000. Many 8-bit home computers ran MOS or Zilog processors; the Macintosh, the Amiga, the Atari ST and the Sega Mega Drive all ran Motorola’s 68000.
Fast facts
- Founded: 25 September 1928, in Chicago, as the Galvin Manufacturing Corporation. The Motorola name began in 1930 on a car radio and became the company’s name in 1947.
- First mass-produced semiconductor: a germanium power transistor for car radios, 1955.
- Processors: 6800 (1974), 6809 (1979), 68000 (sampling from 1979) and its successors, and the PowerPC with Apple and IBM.
- Later history: the chip business became Freescale Semiconductor in 2004 and was bought by NXP in 2015. The rest of Motorola split into Motorola Solutions and Motorola Mobility in 2011.
From car radios to transistors
Paul Galvin and his brother Joseph started the company with a battery eliminator, a converter that let battery radios run from the mains. In 1930 they made a car radio and named it by joining “motor” to “ola”, a sound-suggesting ending. Motorola’s own history dates its first mass-produced semiconductor to 1955: a germanium transistor for car radios, which it calls the world’s first commercial high-power transistor.
By the 1990s Motorola made “radios, telephones, satellites, displays, car parts and all sorts of electronic components”, Amiga Format told its readers in 1995, with “big chip factories in Scotland and the Far East”.
The 6800 and the engineers who left
Motorola’s first microprocessor was the 8-bit 6800, introduced in 1974. Its datasheet describes two accumulators, one 16-bit index register, a 64K address space and 72 instructions, with input and output handled like memory. Motorola built a family of support chips around it, including a Peripheral Interface Adapter for parallel ports and an Asynchronous Communications Interface Adapter for serial ones. By November 1975 BYTE could report that “the first Motorola 6800 kits have just been announced”, and Southwest Technical Products advertised its 6800 computer in the same issue.
Chuck Peddle had worked on the 6800’s peripheral chips and sold the processor to customers who found it too expensive. When Motorola told him to stop work on a cheaper one, he left for MOS Technology in 1974, taking several of the 6800’s engineers with him. MOS announced two processors with the same instructions: the 6501, which fitted the 6800’s pinout, at $20, and the 6502, with a different pinout and its own clock generator, at $25. Motorola sued in November 1975. The trade weekly Electronics reported in April 1976 that the case had been settled: MOS agreed to stop selling the 6501 and to pay Motorola $200,000. The 6502 was unaffected.
The two families stayed related. Neither processor has special input and output instructions, BYTE’s Daniel Fylstra noted: both treat a peripheral chip as memory. MOS also planned “a similar set of chips” to Motorola’s PIA and ACIA, and the Atari 400 and 800 read their joysticks through one of them, a 6520 PIA.
The 6809
Motorola’s own answer to the 8-bit competition was the 6809, designed by Terry Ritter and Joel Boney in Austin and on sale from 1979. It kept an 8-bit data bus but added 16-bit registers and arithmetic, two stack pointers and addressing built for position-independent code. It found its way into the Dragon 32, the Tandy Color Computer, the Vectrex and Williams’ arcade boards for Defender, Robotron and Joust. The 6809 entry tells that story in full.
The 68000 family
In May 1979 BYTE reported that “Motorola expects to start sampling their 68000 this month”, and by September the price was $249 each. The 68000 has sixteen 32-bit registers and a 16-megabyte address space, but a 16-bit data bus, so Motorola called it a “16-/32-Bit Microprocessor”. Most of its instructions work with most of its registers and addressing modes, which made it more regular to program than the 8-bit chips before it.
Motorola extended it into a family that kept the same instructions:
| Processor | What it added | Examples |
|---|---|---|
| 68008 | The 68000 with an 8-bit data bus | Sinclair QL |
| 68010 | Recoverable bus errors for virtual memory; a movable exception table | Fits a 68000’s socket |
| 68020 | Full 32-bit data and address buses, an instruction cache, a coprocessor interface | Amiga 1200 (as the 68EC020) |
| 68030 | A built-in memory management unit and a data cache | Amiga 3000 and 4000/030 |
| 68040 and 68060 | Built-in floating point and much faster pipelines | Amiga 4000/040 and accelerator cards |
Amiga Format said in 1995 that Motorola had designed the 68020 in 1984 “to power UNIX workstations”, and that the big steps in speed came with the even-numbered chips, each “averaging twice the speed” of the one before. That, it suggested, was the real reason Motorola skipped the name 68050.
Where the 68000 went
- Apple Macintosh (1984). Apple’s Inside Macintosh describes a “Sixteen-bit Motorola MC68000 with eight 32-bit data registers”; Amiga Format notes that the first 68000s, used in Apple’s Lisa, ran at 4 MHz.
- Commodore Amiga and Atari ST. Jay Miner left Atari because it would not fund “a 68000 machine”; the Amiga was the result.
- Sinclair QL, with the 68008.
- Sharp X68000, named after its processor.
- Sega Mega Drive, with a 68000 as its main processor alongside a Z80. The Mega-CD add-on brought a second 68000, and Sega’s service manual describes the combined system as having “the CPU (68000 & Z80) of the Mega Drive side” plus its own.
- Neo Geo, SNK’s arcade and home system, with a 68000 as its main processor.
PowerPC
Edge traced Apple’s move to a new processor to “the historic agreement ratified by Apple, IBM and Motorola in October 1991”, which “laid down the architecture for a new family of RISC processors, the Motorola-manufactured PowerPC chips”. By 1994 Apple was selling Power Macintosh computers built around them. Amiga Format wrote in 1995 that Motorola was “probably going to stop further development work on the 68000 series”, though it would keep making the chips. The 68000’s instruction set continued in Motorola’s ColdFire processors for embedded systems, which its 1997 programmer’s manual describes as streamlined members of the “68000 Family”.
Sources
- Motorola Solutions, “Timeline” (web, secondary): the 1928 founding, the battery eliminator, the 1930 car radio and the Motorola name, the 1947 company name, the 1955 transistor, the 6800 in 1974, the 2011 split. https://www.motorolasolutions.com/en_us/about/history/timeline.html
- Amiga Format issue 74, August 1995: Simon Goodwin, 68000 feature part 2, with the box “Who are Motorola?” (the company’s products and factories, the 6800 in 1974), the even-numbered steps and the missing 68050, and Motorola’s plans for the 68000 series. Issue 73, July 1995: part 1 (the 68020 in 1984, the 68030, the Lisa’s 4 MHz 68000), and a news feature describing the PowerPC in the Power Macintosh.
- Motorola, MC6800 8-Bit Microprocessing Unit datasheet: registers, addressing and instruction count.
- BYTE issue 3, November 1975, pp. 56–59: Daniel Fylstra’s comparison of the 6800 and the MOS 6500 series, “Son of Motorola, or, the $20 CPU Chip”; the 6800 kits; and, in the same issue, the Southwest Technical Products 6800 advertisement.
- BYTE, May 1979, p. 118, and September 1979, p. 116: the 68000’s sampling and price.
- Wikipedia, “MOS Technology” (web, secondary), citing Electronics, 13 November 1975, p. 38 (“Motorola seeks to stop microprocessor foe”) and 1 April 1976, p. 39 (“Motorola, MOS Technology settle patent suit”): the lawsuit and the settlement. https://en.wikipedia.org/wiki/MOS_Technology
- For Peddle’s departure and the 6502’s design, see the sources for Chuck Peddle and 6502; for Miner and the 68000 machine Atari refused, see Jay Miner; for the 6809, see 6809; for the 68000’s registers, timings and family, see 68000.
- Apple, Inside Macintosh, volume I (1984): the MC68000.
- Sega, Mega-CD Maintenance Manual: the Mega-CD’s own 68000 alongside the Mega Drive’s 68000 and Z80.
- Edge issue 19, April 1995: the Apple, IBM and Motorola agreement of October 1991 and the Power Macintosh.
- Amiga Format issue 63, September 1994: the PowerPC “developed jointly between Motorola, Apple and IBM”, in a Power Macintosh.
- Motorola, ColdFire Microprocessor Family Programmer’s Reference Manual, revision 1.0 (1997), section 7.
- Wikipedia, “Freescale Semiconductor” (web, secondary): Freescale’s initial public offering after Motorola divested its Semiconductor Products Sector in 2004, and NXP’s acquisition, completed on 7 December 2015. https://en.wikipedia.org/wiki/Freescale_Semiconductor