Motorola 6800
The 6800 is an 8-bit microprocessor designed and first manufactured by Motorola in 1974. The MC6800 microprocessor was part of the M6800 Microcomputer System that also included serial and parallel interface ICs, RAM, ROM and other support chips. A significant design feature was that the M6800 family of ICs required only a single five-volt power supply at a time when most other microprocessors required three voltages. The M6800 Microcomputer System was announced in March 1974 and was in full production by the end of that year. American Microsystems was licensed as the second source.
The 6800 has a 16-bit address bus that can directly access of memory and an 8-bit bi-directional data bus. It has 72 instructions with seven addressing modes for a total of 197 opcodes. The original MC6800 could have a clock frequency of up to. Later versions had a maximum clock frequency of.
In addition to the ICs, Motorola also provided a complete assembly language development system. The customer could use the software on a remote timeshare computer or on an in-house minicomputer system. The Motorola EXORciser was a desktop computer built with the M6800 ICs that could be used for prototyping and debugging new designs. An expansive documentation package included datasheets on all ICs, two assembly language programming manuals, and a 700-page application manual that showed how to design a point-of-sale terminal around the 6800.
The 6800 was popular in computer peripherals, test equipment applications and point-of-sale terminals. It has also been used in arcade games and pinball machines. The MC6802, introduced in 1977, included 128 bytes of RAM and an internal clock oscillator on chip. The MC6801 and MC6805 included RAM, ROM and I/O on a single chip and were popular in automotive applications. Some MC6805 models integrated a Serial Peripheral Interface. The Motorola 6809 was an updated compatible design.
History
Motorola's history in semiconductors
Galvin Manufacturing Corporation was founded in 1928; the company name was changed to Motorola in 1947. They began commercial production of transistors at a new US$1.5 million facility in Phoenix, Arizona in 1955.By the mid-1960s, Motorola had expanded their semiconductor division under the direction of Lester Hogan. Motorola's transistors and integrated circuits were used in-house for their communication, military, automotive and consumer products and they were also sold to other companies. In 1968, Robert Noyce left Fairchild Semiconductor to found Intel, and Fairchild responded by hiring Hogan as the new CEO. Eight other Motorola employees moved with him, they became known as "Hogan's heroes". The resulting chaos was nevertheless short lived, and the company continued to grow through this period.
By 1973 the Semiconductor Products Division had sales of $419 million and was the second largest semiconductor company after Texas Instruments.
5065
By the early 1970s it was clear that most of the large companies in the semiconductor space, including Fairchild and the still-new Intel, were planning to introduce microprocessors. Intel began shopping around the initial concept of what would become the Intel 4004, and on their sales trips they visited Victor Comptometer in Chicago looking for potential customers. Victor had introduced the world's first electronic calculator that used integrated circuits, the Victor 3900. There, Tom Bennett saw the design.In 1971, Motorola decided to enter the calculator business. Looking for someone to lead the effort, they hired Bennett away from Victor. Shortly after joining, Olivetti visited Motorola with a outline of a design for a microprocessor they were planning to use in a series of programmable calculators. Motorola agreed to complete the design and produce it on their PMOS lines in Phoenix.
While the design was eventually completed successfully, their fab proved unable to produce the chips. The problems with the line had become obvious with a number of similar failures; it also proved unable to make competitive memory devices and other designs. To save the contract, Motorola licensed the design to their competitor, Mostek, with the requirement that Mostek could only sell outside the calculator market. Mostek then put the design on the market as the Mostek 5065.
Development team
Customers continued to approach the company with new ideas, and it became increasingly obvious that these concepts could be implemented using a single flexible microprocessor design. A new effort began in late 1971, but in early 1972, the marketing department returned a report stating they could only sell 18,000 over a five year period. Unconvinced, Bennett hired Link Young to try again. Young returned with a potential order for 200,000 from National Data Corporation, more than enough to start design work.The team was composed of designer Tom Bennett, engineering director Jeff LaVell, product marketer Link Young and systems designers Mike Wiles, Gene Schriber and Doug Powell. They were all located in Mesa, Arizona, in greater Phoenix. By the time the project was finished, Bennett had 17 chip designers and layout people working on five chips. LaVell had 15 to 20 system engineers and there was another applications engineering group of similar size.
Tom Bennett had a background in industrial controls and had worked for Victor Comptometer in the 1960s designing the first electronic calculator to use MOS ICs, the Victor 3900. In May 1969 Ted Hoff showed Bennett early diagrams of the Intel 4004 to see if it would meet their calculator needs. Bennett joined Motorola in 1971 to design calculator ICs. He was soon assigned as the chief architect of the microprocessor project that produced the 6800. Others have taken credit for designing the 6800. In September 1975 Robert H. Cushman, EDN magazine's microprocessor editor, interviewed Chuck Peddle about MOS Technology's new 6502 microprocessor. Cushman then asked "Tom Bennett, master architect of the 6800", to comment about this new competitor. After the 6800 project Bennett worked on automotive applications and Motorola became a major supplier of microprocessors used in automobiles.
Jeff LaVell joined Motorola in 1966 and worked in the computer industry marketing organization. LaVell had previously worked for Collins Radio on their C8500 computer that was built with small scale ECL ICs. In 1971, he led a group that examined the needs of their existing customers such as Hewlett-Packard, National Cash Register, Control Data Corporation, and Digital Equipment Corporation. They would study the customer's products and try to identify functions that could be implemented in larger integrated circuits at a lower cost. The result of the survey was a family of 15 building blocks; each could be implemented in an integrated circuit. Some of these blocks were implemented in the initial M6800 release and more were added over the next few years. To evaluate the 6800 architecture while the chip was being designed, LaVell's team built an equivalent circuit using 451 small scale TTL ICs on five 10 by 10 inch circuit boards. Later they reduced this to 114 ICs on one board by using ROMs and MSI logic devices.
John Buchanan was a memory designer at Motorola when Bennett asked him to design a voltage doubler for the 6800. Typical n-channel MOS IC's required three power supplies: −5 volts, +5 volts and +12 volts. The M6800 family was to use only one, +5 volts. It was easy to eliminate the −5 volt supply by using an internal voltage inverter, but the enhancement-mode logic also needed a supply of 10 to 12 volts. To address this, the design added an on-chip voltage doubler. Buchanan did the circuit design, analysis and layout for the 6800 microprocessor. He received patents on the voltage doubler and the 6800 chip layout. Rod Orgill assisted Buchanan with analyses and 6800 chip layout. Later Orgill would design the MOS Technology 6501 microprocessor that was socket compatible with the 6800.
Bill Lattin joined Motorola in 1969 and his group provided the computer simulation tools for characterizing the new MOS circuits in the 6800. Lattin and Frank Jenkins had both attended UC Berkeley and studied computer circuit simulators under Donald Pederson, the designer of the SPICE circuit simulator. Motorola's simulator, MTIME, was an advanced version of the TIME circuit simulator that Jenkins had developed at Berkeley. The group published a technical paper, "MOS-device modeling for computer implementation" in 1973 describing a "5-V single-supply n-channel technology" operating at 1 MHz. They could simulate a 50 MOSFET circuit on an IBM 370/165 mainframe computer. In November 1975, Lattin joined Intel to work on their next generation microprocessor.
Bill Mensch joined Motorola in 1971 after graduating from the University of Arizona. He had worked several years as an electronics technician before earning his BSEE degree. The first year at Motorola was a series of three-month rotations through four different areas. Mensch did a flowchart for a modem that would become the 6860. He also worked the application group that was defining the M6800 system. After this training year, he was assigned to the 6820 Peripheral Interface Adapter development team. Mensch was a major contributor to the design of this chip and received a patent on the IC layout and was named as a co-inventor of seven other M6800 system patents. Later Mensch would design the MOS Technology 6502 microprocessor.
Mike Wiles was a design engineer in Jeff LaVell's group and made numerous customer visits with Tom Bennett during 6800 product definition phase. He is listed as an inventor on eighteen 6800 patents but is best known for a computer program, MIKBUG. This was a monitor for a 6800 computer system that allowed the user to examine the contents of RAM and to save or load programs to tape. This 512 byte program occupied half of an MCM6830 ROM. This ROM was used in the Motorola MEK6800 design evaluation kit and early hobby computer kits. Wiles stayed with Motorola, moved to Austin and helped design the MC6801 microcontroller that was released in 1978.
Chuck Peddle joined the design team in 1973 after the 6800 processor design was done but he contributed to overall system design and to several peripheral chips, particularly the 6820 parallel interface. Peddle is listed as an inventor on sixteen Motorola patents, most have six or more co-inventors. Like the other engineers on the team, Peddle visited potential customers and solicited their feedback. Peddle and John Buchanan built one of the earliest 6800 demonstration boards. In August 1974, Chuck Peddle left Motorola and joined a small semiconductor company in Pennsylvania, MOS Technology. There he led the team that designed the 6500 microprocessor family.