Technologizer has published a very interesting article on Osborne Computers, and its founder, Adam Osborne.  Osborne computers was started 30 years ago (April 3rd 1981).  They were the fastest growing, and fastest failing company in Silicon Valley, impressive even today. Adam Osborne was one of the most important people in Silicon Valley (along with Bill Gates and Steve Jobs).  His books in the 70′s are still invaluable resources for collectors, I have several editions of ‘An Introduction to Microcomputers’ which provide an invaluable reference to some of the chip designs of the 1970′s and early 1980′s.

The Osborne 1, the first wildly successful portable, was based on a Zilog Z80A processor and ran the then popular CP/M OS.  If it wasn’t for cash flow problems, Osborne computers may very well have still been making computers today.  It is also interesting that Mr. Osborne had a habit of picking designs that ended up to be not very successful (he chose the Zilog Z8000 and Intel 8089 I/O processor as ‘Chips of the Year’ in 1980)

In 1974 Federico Faggin left Intel after working on the 8-bit 8080 processor.  He formed a company called ZiLOG and developed a much improved version of the 8080 called the Z80.  It was released in 1976 after only 18 months of design.  The Z80 was faster, cheaper, and simpler to build around then the 8080 and enjoyed extremely wide use.  ZiLOG designed the CPU but it was marketed differently then most at the time.  Any company could purchase a license to the design, and build them royalty free.  They were also free to do with the design as they pleased.  This resulted in dozens of companies making clones/versions of it. The Soviets made unlicensed copies as well. In fact other companies made more Z80s then ZiLOG did themselves.

Zilog Z-80 CPU 8400X CS - 1979 2.5MHz

The Z80 was not the only processor that ZiLOG made.  Some of the processors/part numbering can be a bit confusing so we’ll look at each family and part that Zilog made up through 1985.  After 1985 CMOS designs came out as well as dozens of variations.  We just want to look at the first ten years of ZiLOG.

Zilog Z8300-3PS - 1984 2.5MHz

The Z80 itself was, of course, similar to the 8080 but single voltage, and only required a single clock phase.  It was available in speeds of 2.5-8MHz.  ZiLOG also made a low-power version known as the Z80L (Z8300) that ran from 1-2.5MHz.  That’s really all there was to the Z80 family up through 1985.

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In a recent deal to try to solve their cash problems, and streamline profitability, Zilog sold off its secure transaction products (namely 32bit ARM processors) to Maxim (who through the purchase of Dallas, makes many MCS-51 controllers),  They also sold off their wireless division to Maxim (and the software portion of this to a company called UEI)

What does this leave? Essentially the classic Z80 processor that has been around for the last 33 years, and all the related extentions there of.  Old designs tend to stick around for a long time, and the Z80 is no exception.

Source: EE Times