Wrinkles and the MCS-51

From anti-lock brakes to children’s toys

At a Glance

  • 1977

  • Learning from the past to improve the future.

  • Product engineer Ronald Towle recalled, “It was very much what I would call guerrilla engineering... You had to figure out how to get things done” without the usual support infrastructure.



In December 1977, Intel engineer John Wharton forgot his wallet and asked a friend to take him to lunch. The friend, manager Lionel Smith, said he had to attend a lunch meeting, but invited Wharton to join him. That free meal would lead one of the best-selling microcontroller series in the world, the  MCS-51.

In contrast to Intel’s first microcontroller series, the MCS-48, the new MCS-51 was designed to have an adaptable architecture that would remain viable for a long time to come. 8051 die shot, undated.

Intel had introduced first microcontroller series, the MCS-48, just over a year earlier. The product had enough traction in the market that the company had already implemented several improvements to it, and the lunch meeting was to discuss ways to enhance it further. Listening to the plans on the table, Wharton thought it made more sense to begin pursuing a new product that could incorporate the things Intel had learned from the MCS-48 but which would be designed from scratch. Later, at Smith’s prompting, Wharton wrote up a proposal to that effect. Wharton’s proposal wound up being the beginning of the MCS-51.

The design went smoothly overall but was not without disruption. The biggest challenges presented themselves midway through development when the microcontroller group began relocating from Santa Clara to Intel’s new facility in Arizona. The team wound up split between the two sites, and in the days before the PC, communications were difficult. Most complex information had to be physically transported back and forth in hard copy. Moreover, the Arizona facilities were not fully up and running at first, so employees there often had to get creative to meet their resource needs. Product engineer Ronald Towle recalled, “It was very much what I would call guerrilla engineering. … You had to figure out how to get things done” without the usual support infrastructure.

Attitudes like Towle’s led to a triumphant final product. In contrast to the MCS-48, which was always intended to have a relatively short lifespan, the MCS-51 was designed to be an enduring, widely adaptable architecture, so the original series and its variants became one of the most prolific device lines in history. Introduced in 1980, Intel sold 100 million units in the first decade of the product’s existence. It turned up in everything from anti-lock brakes and airplanes to musical instruments and children’s toys.

Perhaps its most intimate (and cutest) application was in Wrinkles the Talking Dog. When children hugged Wrinkles and heard him laugh or say things like “I am happy,” it was an MCS-51 device that synthesized his voice to make the interaction possible.

Wrinkles the talking dog could say over 1,000 phrases, all of them made possible by an Intel 80C51. Talking Wrinkles doll, ca. 1986.

Intel kept making new variants of the MCS-51 well into the twenty-first century, and second source suppliers continued to do so thereafter. As late as 2008, Bob Wickersheim, Intel’s lead design engineer on the original product, still enjoyed it when people asked him what he did for a living, because he got to respond, “Chances are very high that a chip I worked on exists somewhere in your house.”