ZiLOG, Redux, Redux, Redux

December 14, 2009

Jack Ganssle-December 14, 2009

In 1974 (according to most sources, or 1973 according to their most recent annual report) Frederico Faggin left Intel to form ZiLOG with Ralph Ungermann. Their first product was the wildly popular Z80 CPU, which even 35 years later is still in production. I wonder if any other CPU has had such a long life.

ZiLOG capitalized on the Z80's success with a variety of other processors, such as the ill-fated Z800 which was Z80-compatible but offered much higher performance. That part never made it to market. The Z280, though, went into production. Somewhat Z80-compatible it offered cache, a range of on-board peripherals, and 24 address lines. Excessively complex the part suffered from a variety of bugs that ZiLOG never managed to iron out.

At the time a company executive told me it had been manually taped out and the cost to move the design to their current CAD system was prohibitive, so no updates were planned. The part soon became a market failure.

Hitachi, though, upscaled the Z80 into their 64180 which had a primitive on-board MMU that extended the address bus to 20 bits. ZiLOG offered the part under the name Z180, and it gained substantial market share, and is also still available today.

They entered the 16 bit market with the Z8000, a very sophisticated chip, which found a ready niche mostly in the military. Overshadowed by the more or less contemporaneous x86 and 68000, it never reached its full potential despite an orthogonal architecture every engineer loved.

Today the company offers other Z80-like parts which have become somewhat successful. Their Z8, a microcontroller, came out in 1979 and is still alive in updated variants.

Sounds like a success story! Alas, ZiLOG was a perennial money-loser, though they did have a shining moment in the 1990s when sales were as high as $223 million. But sales fell, they filed for bankruptcy in 2001, and have struggled since then, losing money at least every year since 2004 (with the exception of a small profit last year generated entirely by the sale of a part of their business). Sales were $36m last year, which was the low point of a steady stream of declining revenue.

Now Ixys Corporation has offered to buy the company for $62.4m in cash, which is roughly the current valuation of ZiLOG's stock. Having had a close association with Zilog in their pre-camelcase years, I'm happy to see them in this alliance, which can only add strength to their tottering balance sheet, and wish the company future success. Perhaps 35 years from now, in 2044, the Z80 will still be going strong.

Jack G. Ganssle is a lecturer and consultant on embedded development issues. He conducts seminars on embedded systems and helps companies with their embedded challenges. Contact him at His website is

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