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The 6800 ("''sixty-eight hundred''") was 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.〔 "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.〕 The 6800 architecture and instruction set were influenced by the then popular Digital Equipment Corporation PDP-11 mini computer.〔 "It introduced its 6800 microprocessor in March 1974. The device needed only one +5-volt power supply, in contrast with the Intel 8080's three. And it had an untangled bus structure like the one the Digital Equipment Corp. put in its PDP-11 minicomputers."〕〔 "The microprocessor phenomenon passed the PDP-11 by, even though elements of its architecture turned up in microprocessor designs (especially the Motorola 6800)." - Author interviewed Gordon Bell, designer of the PDP-11〕 The 6800 has a 16-bit address bus that could 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.〔 "… MC6800, which was introduced in 1974. The device was built in six-micron NMOS technology with about 4000 transistors."〕 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 computer terminal. The 6800 was popular in computer peripherals, test equipment applications and point-of-sale terminals. The MC6802, introduced in 1977, included 128 bytes of RAM and an internal clock oscillator on chip. The MC6801 and MC6805 included with RAM, ROM and I/O on a single chip were popular in automotive applications. == Motorola's history in semiconductors == (詳細はtransistors and integrated circuits were used in-house for their communication, military, automotive and consumer products and they were also sold to other companies. By 1973 the Semiconductor Products Division (SPD) had sales of $419 million and was the second largest semiconductor company after Texas Instruments. In the early 1970s Motorola started a project that developed their first microprocessor, the MC6800. This was followed by single-chip microcontrollers such as the MC6801 and MC6805. In 1999 Motorola spun off their analog IC, digital IC and transistor business to ON Semiconductor of Phoenix Arizona. In 2004 they spun off their microprocessor business to Freescale Semiconductor of Austin, Texas. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Motorola 6800」の詳細全文を読む スポンサード リンク
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