of Microprocessors

130 MUSICAL ApPLICATIONS OF MICROPROCESSORS
a 12-bit microprocessor that was Digital Equipment PDP-8 software
compatible. A new company called Zilog was formed to make a substantially
improved 8080 called, appropriately enough, the Z-80. All of these
companies ultimately offered complete computers built around their microprocessors,
but none was ever successful in the general microcomputer
market.
The Altair 8800 Microcomputer
The next milestone in the popularization of microprocessors has to be
the announcement in January 1975 of the Altair 8800 microcomputer kit by
MITS as a feature article in another major hobby electronics magazine.
Announcement is emphasized because machines were not delivered until
several months later. Nevertheless, tremendous excitement and quite a bit of
confusion was created by the announcement. The excitement was due to the
microprocessor chip used: the yet to be generally available, exceedingly
powerful (compared to the 8008) 8080. Also, the availability of a kit interested
many more people who were not skilled enough to acquire parts and
etch printed circuit boaids themselves. One confusing factor was the price of
the kit; $60 less than the current price of the microprocessor IC itself, and
the kit contained cabinet, power supply, and several dozen additional ICs
and other parts necessary to support the microprocessor. Most could not
believe that the $360 8080 chip was actually included! This time thousands
of machines were ordered and delivered, and real magazines sprang up to
meet the tide of interest created.
MITS itself was completely overwhelmed with thousands of orders,
which explains the delivery delays that have since become commonplace in
the industry. Had they been able to deliver immediately, the subsequent
evolution of the hobby computer industry may have been entirely different
with one manufacturer in a position of complete dominance. As it was, the
market was thrown wide open to dozens ofsmall companies that materialized
to meet the demand.
Since the Altair used a parallel bus structure with sockets for plugging
in extra memory and peripheral equipment interfaces, these same companies
were able to effectively compete in the add-on market even after MITS started
delivering machines. This bus structure, now called the S-lOO bus, has
become a defacto standard in 8080 (and later Z-80) systems because such a
variety of CPU, memory, and peripheral interface boards are available. Keen
competition in the S-lOO marketplace kept prices low and innovation high.
The First Wave
The original Altair, and later lmsai and some others, were strictly
"hobby" computers. They were nearly always built from kits and expanded
piecemeal as time and resources permitted. In most cases, software consisted