Microprocessor (3 p. 217ff)

Improving chip density (MOS) leads to the idea of a processor on a chip.
But what is it good for?

Busicom of Japan
- top seller of hand-held caculators
- has a line of products with different capabilities
- wants custom designed logic chips for advanced math functions
- approaches Intel

Intel - Intel's Microprocessor History
- Intel proposes a chip with general-purpose computer concept
- call a subroutine, execute, return
- store the subroutines in memory (rather than wiring them in to the logic chip)
- moves the complexity from the logic chip to memory
- add or modify functions by changing what's in memory

- Intel sells more memory chips
- Intel lowers cost to Busicom in return for rights to market logic chip to other customers

1971 Intel advertises the 4004
- "a microprogrammable computer on a chip"
- 4 chip set (processor, ROM, RAM, I/O)
- 4 bit processor

- Ted Hoff @ Intel - initial concept
- Federico Faggin - implementation in silicon
- Stan Mazor - detailed design
- Masatoshi Shima @ Busicom contributed

- Gary Boone @ TI comes up with similar ideas about the same time

1972 - Intel 8008, an 8 bit processor
- based on potential work for mainframe terminals for Computer Terminal Corp (later Data Point)

1973 Rockwell and a few other also offering microprocessors

1974 Intel 8080, $360
-begins to approach the power of comtemporary minis

Intel's approach
- buy 8080
- write special software
- burn it into ROM
- and you have an embedded controller

Educational kits for about $200 by Intel and others
- micro, RAM, ROM, control chip
- all mounted on a printed circuit board
- written material on how to program this system

1974 Intel offers Intellec 4 development system (for 4 bit processors)
- later Intellec 8 for 8 bit processors
- developed for Intel by Gary Kildall
- these were general purpose computers
- purpose was to sell chips
- not available to the public

1. William Aspray, ed., Computing Before Computers (Ames, IA: Iowa State University Press, 1990 ). Also available online at http://www.computerhistory.org/collections/DocumentArchive/Documents/Books/Computing Before Computers/CBC.html (Computer History Museum, accessed 2004 Aug 11).

2. Martin Campbell-Kelly and William Aspray. Computer: A History of the Information Machine (Basic Books, 1996).

3. Paul E. Ceruzzi, A History of Modern Computing, 2nd ed. (Cambridge, MA: MIT Press, 2003).

4. Paul E. Ceruzzi, Reckoners, the Prehistory of the Digital Computer, from Relays to the Stored Program Concept, 1935-1945 (Westport, CT: Greenwood Press, 1983). Also available online at http://www.computerhistory.org/collections/DocumentArchive/Documents/Books/Reckoners/Reckoners.html (Computer History Museum, accessed 2003 Sep 27).