Hardware Reference
In-Depth Information
Because of Intel's success in memory chip manufacturing and design, Japanese manufac-
turer Busicom asked Intel to design a set of chips for a family of high-performance pro-
grammable calculators. At the time, all logic chips were custom-designed for each applic-
ation or product. Because most chips had to be custom-designed specific to a particular
application, no one chip could have widespread usage.
Busicom's original design for its calculator called for at least 12 custom chips. Intel
engineer Ted Hoff rejected the unwieldy proposal and instead proposed a single-chip,
general-purpose logic device that retrieved its application instructions from semiconduct-
or memory. As the core of a four-chip set including read-only memory (ROM), random
access memory (RAM), input/output (I/O) and the 4004 processor, a program could con-
trol the processor and essentially tailor its function to the task at hand. The chip was gen-
eric in nature, meaning it could function in designs other than calculators. Previous chip
designs were hard-wired for one purpose, with built-in instructions; this chip would read
a variable set of instructions from memory, which would control the function of the chip.
The idea was to design, on a single chip, almost an entire computing device that could
perform various functions, depending on which instructions it was given.
In April 1970, Intel hired Frederico Faggin to design and create the 4004 logic based
on Hoff's proposal. Like the Intel founders, Faggin came from Fairchild Semiconductor,
where he had developed the silicon gate technology that would prove essential to good
microprocessordesign.Duringtheinitiallogicdesignandlayoutprocess,Fagginhadhelp
fromMasatoshiShima,theengineeratBusicomresponsibleforthecalculatordesign.Shi-
ma worked with Faggin until October 1970, after which he returned to Busicom. Faggin
received the first finished batch of 4004 chips at closing time one day in January 1971,
working alone until early the next morning testing the chip before declaring, “It works!”
The 4000 chip family was completed by March 1971 and put into production by June
1971.Itisinteresting tonote that Faggin actually signed the processor die with hisinitials
(F.F.), a tradition that others often carried out in subsequent chip designs.
There was one problem with the new chip: Busicom owned the rights to it. Faggin knew
thattheproducthadalmostlimitlessapplication,bringingintelligencetoahostof“dumb”
machines. He urged Intel to repurchase the rights to the product. Although Intel founders
Gordon Moore and Robert Noyce championed the new chip, others within the company
wereconcernedthattheproductwoulddistractIntelfromitsmainfocus:makingmemory.
They were finally convinced by the fact that every four-chip microcomputer set included
two memory chips. As the director of marketing at the time recalled, “Originally, I think
wesawitasawaytosellmorememories, andwewerewillingtomaketheinvestment on
that basis.”
