Motorola 6800

For the 16/32-bit microprocessor introduced in 1979, see Motorola 68000.
Motorola 6800
Motorola MC6800 microprocessor
General information
Launched1974; 50 years ago (1974)
Common manufacturer
Performance
Max. CPU clock rate1 MHz to 2 MHz
Data width8 bits
Address width16 bits
Architecture and classification
Instruction set6800
Number of instructions72
Physical specifications
Transistors
  • 4,100
Package
History
Successors

The 6800 ("sixty-eight hundred") is an 8-bit microprocessor designed and first manufactured by Motorola in 1974. 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. 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.[2][3]

The 6800 has a 16-bit address bus that can directly access 64 KB 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 1 MHz. Later versions had a maximum clock frequency of 2 MHz.[4][5]

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 (a computerized cash register) around the 6800.[6]

The 6800 was popular in computer peripherals, test equipment applications and point-of-sale terminals. It has also been used in arcade games[7] and pinball machines.[8] 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 (SPI).[9] The Motorola 6809 was an updated compatible design.

  1. ^ Puckett, Dale (1981-04-13). "68XX's Family Is Extended". InfoWorld. 3 (7). CW Communications: 46–47 – via Google Books.
  2. ^ "Motorola joins microprocessor race with 8-bit entry". Electronics. 47 (5). New York: McGraw-Hill: 29–30. March 7, 1974.
  3. ^ "Microcomputer system runs on one 5-V supply". Electronics. 47 (26). New York: McGraw-Hill: 114–115. December 26, 1974. "Motorola's M6800 microcomputer system, which can operate from a single 5-volt supply, is moving out of the sampling stage and into full production." The small-quantity price of the MC6800 is $360. The MC6820 PIA cost $28.
  4. ^ M6800 Microcomputer System Design Data. Phoenix AZ: Motorola. 1976.
  5. ^ Daniels, R. Gary; William C. Bruce (April 1985). "Built-In Self-Test Trends in Motorola Microprocessors". IEEE Design & Test of Computers. 2 (2). IEEE: 64–71. doi:10.1109/MDT.1985.294865. S2CID 22719798. "… MC6800, which was introduced in 1974. The device was built in six-micron NMOS technology with about 4000 transistors."
  6. ^ M6800 Microprocessor Applications Manual. Phoenix AZ: Motorola. 1975.
  7. ^ "System 16 – Atari 6800 Based Hardware". system16.com. Archived from the original on 2018-03-16. Retrieved 2018-03-15.
  8. ^ "Mark's Guide to Williams System 3 Through 7 Troubleshooting and Repair". Archived from the original on 2018-02-16. Retrieved 2018-03-15.
  9. ^ components :: motorola :: dataBooks :: 1983 Motorola 8-Bit Microprocessor and Peripheral Data.