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Apple co-founder Steve Wozniak's keynote speech at last
week's Flash Memory Summit did
not go according to plan. Instead of speaking on "design innovation with solid
state technologies," as stated in the program brochure, Wozniak gave an
entertaining and sometimes hilarious account of his early efforts at computer
design and his struggles with memory back in the 1960s and 1970s.
There was an important message behind the amusing anecdotes
- that memory selection and integration is a key part of any electronic design.
That's no less true for today's systems-on-chip than for 1960's era computers.
The key role of memory in SoC design is one reason that Cadence recently acquired
Denali Software, a provider of memory models and memory controller IP and a
platinum sponsor of the Flash Memory Summit.
Although he's probably best known today for his philanthropic
activities, Wozniak is also chief scientist at Fusion-io, a company bringing new
technology to solid state drives (SSDs). Wozniak said little about that role at
other than to note that the company has taken a unique approach to solid-state
storage and that "I'm glad to be part of them now."
The real focus of Wozniak's talk, as he said, was
"interesting and fun stories of my own technology life when I ran into memory."
Just Stick Your
The first memory device Wozniak built was a relay (he didn't
say when, but from the progression of events, I assume this was during or
before high school). He discovered that if you touch a relay coil when it
releases, you get a big shock. "That's when I learned I was a hardware guy," he
said. Today, Wozniak owns a device that gives random electric shocks to any of
four finger holes. He noted that hardware engineers always stick their fingers
in, and software developers never do.
In high school Wozniak taught himself about computers, and
as a hobby designed computers on paper, never thinking he'd actually make his
living that way someday. He told his father he was going to own a 4K Nova
computer someday; 4K bytes of memory was the minimum needed to load programs.
When his father noted that such a computer would be as expensive as a house,
Wozniak declared he'd live in an apartment.
After high school, Wozniak worked for a Sunnyvale company programming a 20 Mbyte
computer - huge for late 1960s. The California
Dept. of Motor Vehicles bought two, and ran them for 20 years.
Until this point, Wozniak had never actually built anything,
because he had no money to buy the computer hardware. That was especially true
of memory, which he saw as "big magnetic core points with transistors to boost
signals." Then Intel and Intersil came out with 256-bit RAMS, and through a Silicon Valley contact, Wozniak was able to acquire some
Intersil chips. He plugged them into a small computer and ran some programs. He
then destroyed the TTL chips when he stepped on a power cord while demonstrating it to a newspaper editor.
During his third year of college, Wozniak worked on the HP35
scientific calculator, which I still remember as a revolutionary breakthrough
in the 1970s. With 6 micron spacing, the designers were able to get 1,000
transistors on a chip. Wozniak confided that Reverse Polish
Notation, subsequently viewed as a powerful computer science concept, was
used because the ROM memories in the calculators could only hold 500 bytes.
After seeing Pong in a bowling alley, Wozniak built a Pong
machine for his TV with 28 chips. He then got the idea that missing the ball
should bring up a four-letter word. This required two 256-byte PROMS. A
Breakout machine, in contrast, required a 256-byte RAM. Wozniak then discovered
Arpanet and built a terminal that connected to a computer in Boston. A PMOS chip with 1,024 bits of memory
was "perfect," with the lowest cost and pin count.
Beginnings of Apple
By the summer of 1975 Wozniak had met Steve Jobs and had
noticed two important developments - microprocessors and dynamic memory. He
decided to combine a microprocessor with dynamic memory to build a personal computer.
Wozniak bought eight 4K-bit dynamic RAM chips from AMI, and on Jobs' advice
switched to Intel's 4K RAM, which turned out to be the forerunner of today's
DRAMs. The result was the first Apple computer.
The Apple 2 computer was designed "from the ground up to be
a good, fast computer" using some of Wozniak's innovations for screen display,
including a simple approach to representing 16 colors using only 4 bits of
memory. Wozniak's concluding anecdote described how he invented a floppy disk
drive controller in two weeks just so he could attend the Consumer Electronics
Show in Las Vegas
A 2010 Takeaway
The moral of these stories? "The first decision I made for
most projects during my life was what kind of memory to use," Wozniak said. "I
wanted the exact, smallest, simplest, and most importantly, cheapest memory
Computer design has changed a lot since 1975, but memory is
as critical as ever. You cannot build a system that's optimized for
applications development, as described in the EDA360 paper, without choosing and integrating
the best possible memory subsystem. You need to give it the same kind of
priority that Steve Wozniak did 35 years ago. Even in the world of high
technology, some things never change.