Motorola 6800

The MC6800 microprocessor was part of the M6800 Microcomputer System (later dubbed 68xx[1]) that also included serial and parallel interface ICs, RAM, ROM and other support chips.

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.

[12] 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.

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.

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.

[11] 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.

Bill Lattin joined Motorola in 1969 and his group provided the computer simulation tools for characterizing the new MOS circuits in the 6800.

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.

Mike Wiles was a design engineer in Jeff LaVell's group and made numerous customer visits with Tom Bennett during 6800 product definition phase.

[26] 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.

[32] In August 1974, Chuck Peddle left Motorola and joined a small semiconductor company in Pennsylvania, MOS Technology.

They were much more difficult to produce because of an increased sensitivity to contamination that required an ultra clean production line and meticulous process control.

Motorola's n-channel MOS test integrated circuits were complete in late 1971 and these indicated the clock rate would be limited to 1 MHz.

There was a newer fabrication technology that used "depletion-mode" MOS transistors as loads, which would allow smaller and faster circuits (this was also known as depletion-load nMOS).

The 1 MHz clock rate meant the chip designers would have to come up with several architectural innovations to speed up the microprocessor throughput.

[48] The 8080 used same three voltage N-channel MOS process as Intel's existing memory chips allowing full production to begin that April.

In addition to releasing a full set of support chips with the 6800 microprocessor, Motorola offered a software and hardware development system.

[59] Motorola's Semiconductor Products Division would lose thirty million dollars in the next 12 months and there were rumors that the IC group would be sold off.

[citation needed] Chuck Peddle (and other Motorola engineers) had been visiting customers to explain the benefits of microprocessors.

He wrote a memo stating that these instructions were a clear statement that Motorola was abandoning the concept, meaning they could not claim intellectual property against it.

[64] After approaching Mostek and being rejected, in August 1974 Chuck Peddle left Motorola and joined a small semiconductor company in Pennsylvania, MOS Technology.

He was followed by seven other Motorola engineers: Harry Bawcom, Ray Hirt, Terry Holdt, Mike James, Will Mathis, Bill Mensch and Rod Orgill.

Rod Orgill designed the MCS6501 processor that would plug into a MC6800 socket and Bill Mensch did the MCS6502 that had the clock generation circuit on chip.

The IBM Video Graphics Array (VGA), which became ubiquitous (to the point that it is still emulated as the baseline functionality of most modern PC video adapter chips) incorporates a compatible near-superset of the EGA CRTC, still mostly-compatible with the MC6845 (but by this point without the light pen support, which the EGA CRTC retained).

The MC6801 was a single-chip microcomputer (that today would also be called a microcontroller) incorporating a 6802 CPU with 128 bytes of RAM, a 2 KB ROM, a 16-bit timer, 31 programmable parallel I/O lines, and a serial port.

[88] The MITS Altair 8800, the first successful personal computer, used the Intel 8080 microprocessor and was featured on the January 1975 cover of Popular Electronics.

Sphere Corporation of Bountiful, Utah ran a quarter-page advertisement in the July 1975 issue of Radio-Electronics for a $650 USD computer kit with a 6800 microprocessor, 4 kilobytes of RAM, a video board and a keyboard.

[91] Southwest Technical Products Corporation of San Antonio, Texas, officially announced their SWTPC 6800 Computer System in November 1975.

The following 6800 assembly language source code is for a subroutine named memcpy that copies a block of data bytes of a given size from one location to another.

Motorola began making semiconductors in the 1950s.
Block diagram of a M6800 microcomputer system
Motorola 6800 DIP chip pinout
MIKBUG was part of the extensive M6800 microcomputer support developed by Motorola's Application Engineering Group.
A Motorola MC6800 microprocessor registers and I/O lines
A silicon wafer holding many integrated circuit chips
An early advertisement for the Motorola's M6800 family microcomputer system
Introductory advertisement for the MOS Technology MCS6501 microprocessor in August 1975
The M6800 family chips were redesigned to use depletion-mode technology. The MC6820 PIA became the MC6821.
Three typical applications for the MC6800, as shown in a Motorola advertisement from August 1976: a point-of-sale terminal, an electronic signal tester, and a security card entry system.
The SWTPC 6800 computer system, introduced in November 1975, was based on the MEK6800 design evaluation kit chip set.
MITS Altair 680
The Tektronix 4051 graphics computing system used a 6800 microprocessor.