Hardware Reference
In-Depth Information
Intel offered to return Busicom's $60,000 investment in exchange for the rights to the
product. Struggling with financial troubles, the Japanese company agreed. Nobody in the
industryatthetime,evenIntel,realizedthesignificanceofthisdeal,whichpavedtheway
for Intel's future in processors.
The result was the November 15, 1971 introduction of the 4-bit Intel 4004 CPU as part
of the MCS-4 microcomputer set. The 4004 ran at a maximum clock speed of 740KHz
(740,000 cycles per second, or nearly 3/4 of a megahertz), contained 2,300 transistors in
an area of only 12 sq. mm (3.5mm×3.5mm), and was built on a 10-micron process, where
eachtransistor wasspacedabout10microns(millionths ofameter)apart.Datawastrans-
ferred 4 bits at a time, and the maximum addressable memory was only 640 bytes. The
chipcostabout$200anddeliveredaboutasmuchcomputingpowerasENIAC,oneofthe
firstelectronic computers.Bycomparison,ENIACreliedon18,000vacuumtubespacked
into 3,000 cubic feet (85 cubic meters) when it was built in 1946.
The4004wasdesignedforuseinacalculatorbutprovedtobeusefulformanyotherfunc-
tions because of its inherent programmability. For example, the 4004 was used in traffic
light controllers, blood analyzers, and even in the NASA Pioneer 10 deep-space probe.
You can see more information about the legendary 4004 processor at
www.intel4004.com
and
www.4004.com
.
In April 1972, Intel released the 8008 processor, which originally ran at a clock speed of
500KHz (0.5MHz). The 8008 processor contained 3,500 transistors and was built on the
same 10-micron process as the previous processor. The big change in the 8008 was that it
had an 8-bit data bus, which meant it could move data 8 bits at a time—twice as much as
the previous chip. It could also address more memory, up to 16KB. This chip was primar-
ily used in dumb terminals and general-purpose calculators.
The next chip in the lineup was the 8080, introduced in April 1974. The 8080 was con-
ceivedbyFredericoFagginanddesignedbyMasatoshiShima(formerBusicomengineer)
under Faggin's supervision. Running at a clock rate of 2MHz, the 8080 processor had 10
times the performance of the 8008. The 8080 chip contained 6,000 transistors and was
built on a 6-micron process. Similar to the previous chip, the 8080 had an 8-bit data bus,
soitcouldtransfer8bitsofdataatatime.The8080couldaddressupto64KBofmemory,
which was significantly more than the previous chip.
The 8080 helped start the PC revolution because it was the processor chip used in what
is generally regarded as the first personal computer, the Altair 8800. The CP/M operating
system (OS) was written for the 8080 chip, and the newly founded Microsoft delivered its
first product: Microsoft BASIC for the Altair. These initial tools provided the foundation
for a revolution in software because thousands of programs were written to run on this
platform.
