News & Analysis

Will the Real Enchilada Please Stand Up?

Peggy Aycinena

2/26/2001 7:29 PM EST

Will the Real Enchilada Please Stand Up?

On the theory that it's better to ask a stupid question than to make a stupid mistake, I often find myself asking company spokesmen: "What's an SOC?" The answer given in quick reply, usually with a bit of a pedantic chuckle: "An SOC is a system on a chip."

"Yeah, okay. So what's a system on a chip?" The answer to that question never comes as quickly and rarely with a chuckle-pedantic or otherwise. In fact, the answer is usually preceded by a sigh. Why?

Because, most technologists must deal with the same transient semantics in electronics that we all wrestle with. It's a whole lot easier to use a catch-all phrase like system on a chip, and let the meaning be implied, than to articulate the exact definition of such a phrase.

So, after the requisite sigh, what kinds of definitions are in use today for an SOC? Well, let's start with David Shanahan's column in this month's issue: "Today's SOC designs typically contain micro-controllers, digital signal processors, memories, peripherals, and physical-interface connections to external devices all in a single package." That's pretty straightforward, so why look any farther? Well, there are lot of folks out there using definitions other than David's that are neither as clear-cut nor as confident.

Here's a sampling of responses to the deceptively easy question: "What's an SOC?"

  • "First off, it depends on who you're talking to, because depending on the end-use, an SOC can mean so many different things."

  • "It's a combination of analog and digital on a chip-and a large chip at that."

  • "An SOC is a product that ends up in a cell phone and probably has DACs, and so forth."

  • "If you can just drop it into your design, it's an SOC."

  • "I can't define a system on a chip."

  • "If you've got a microprocessor, memory, software, controllers, digital hardware, and analog functions all integrated on a single piece of silicon, you've truly got a system on a chip."

  • "It's a successful chip that can be used in production."

  • "It's a chip that's designed with an end-system in mind."

  • "The world is analog. If you've got a chip that can interface with signals from an analog world and compute an output on a digital single-chip platform, you've got a system on a chip."

  • "If you've got everything that was once on the board now rolled up on the chip, you've got an SOC."

  • "If it's got over 100,000 gates, it's probably a system on a chip."

  • "It's a big chip."

  • "In its simplest sense, it's the integration of a microprocessor-or multiple microprocessors-and some memory, controllers, and interface to the board"

  • "If all kinds of stuff that was once on the board is now on the chip, that's an SOC."

  • "The definition's not important. It's only important that I-as an ASIC designer-think now in terms of designing systems and not just in terms of designing ASICs."

  • "Every chip that has a microprocessor in it is a system on a chip."

  • "It's a generic, knobbly thing."

    And so the definitions go-adding confusion, not clarity, to a technology and a term that glibly describes and inefficiently defines the most promising wave in the future of design. Not surprisingly, I continued to be frustrated with the list of responses I had gleaned from industry until I recently met a feisty ASIC designer long on confidence and short on patience.

    "So, what's an SOC?" I asked him.

    He didn't hesitate for a moment. "An SOC," he said with a flourish, "is the whole enchilada!"

    Excellent. I couldn't have put it better myself.

    Okay. One down, three to go.

    First: "What's an embedded system?" Second: "What's an HDL?" Third, and most important to recent polls in EDA: "What's a tape-out?"



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