of Microprocessors

MICROPROCESSORS 131
of little more than what the owner could write and perhaps copy from
magazine articles or friends at computer club meetings. The mass storage
hardware and operating system software that makes a computer easy and
efficient to use was not often seen on these machines.
Then in 1976-77, three integrated microcomputers were introduced,
two by relatively large companies, and each gained a Large following. The
PET (Personal Electronic Transactor) computer manufactured by Commodore
was the first. Actually, Commodore had already made a name for itself in the
pocket calculator business but at the time was struggling. The PET was truly
integrated with a keyboard, display monitor, and tape cassette storage all in
the same cabinet. Most important, a large amount of software was built-in as
a ROM, including a highly sophisticated (at the time) and speedy BASIC
interpreter and rudimenrary operaring system for controlling the cassette
storage. One weakness in comparison to S-100 computers was the lack of a
convenient expansion facility. The $600 asking price (which later proved to
be a teaser) was an incredible shock, being much less than what a similarly
equipped S-100 type compurer would cost. One reason for the low price was
that Commodore, who had earlier acquired MaS Technology, manufactured
most of the key ICs themselves, including the 6502 microprocessor, the
masked ROM, and the memory ICs. The 6502 in fact had been invented by
MaS Technology while they were independent and had many advantages
over the then popular 8080 in an integrated computer product.
Shortly thereafter, Radio Shack introduced its TRS-80 computer. The
name was simply an abbreviation of the manufacturer (Tandy Radio Shack),
while the 80 referred to its Z-80 microprocessor, which was a substantially
improved 8080. Radio Shack packaged their machine differently than
Commodore did. The computer and keyboard were combined into a single,
somewhat overgrown keyboard case, whereas the display, cassette storage,
and power supply were each separate units. All were connected to the
keyboard unit by cables and each was separately priced. The ROM software
was similar with an operating system and BASIC, although the latter was a
greatly simplified version of the language. Expansion was better provided for
in that larger-capacity-memory ICs could simply be plugged in, and a
separate expansion box having even more memory and a disk controller was
later offered. Pricing for a comparable system turned out to be somewhat less
than the PET's, which had risen to $800. This, coupled with Radio Shack's
thousands of already existing electronics stores, made the machine an instant
hit with sales that quickly outstripped the PET's early lead.
The third popular computer of the period was not designed in the
engineering department ofa large company. Instead it evolved from an earlier
model in the California basement of two entrepreneurs, Steve Wozniak and
Steve Jobs. The Apple II was packaged much like the TRS-80 bur had a
built-in power supply and used a 6502 microprocessor like the PET. Its ROM
operating system was more advanced than the other two, however, but, like