Ridge Avenue’s Giant Brain

The birthplace of computers

It’s now the Marketplace at East Falls, but 3747 Ridge Ave. is the birthplace of something bigger.

Outside, there’s an inconspicuous, blue historical marker. Think of the cell phone pulsating next to you, the car that whizzed by a second ago, and the platform you are on at this very moment. Philadelphia played a massive role in developing the background of this technology.

The inky blue sign only winks. It was placed there in 2006 to commemorate the site of the first commercial digital computer, the Binary Automatic Computer (BINAC). Inside the Marketplace, off to the side of the fresh produce, wine and cheese, one may spot the BINAC exhibit parked in a corner. There is a brand-new ATM directly across from it, as if it were in on the joke.

BINAC at 3747 Ridge Ave. Photo: Dan McGrath

Nearly 63 years ago in the month of July, Dr. John Mauchly and J. Presper Eckert introduced the Electronic Numerical Integrator And Computer (ENIAC) at the Moore School of Electrical Engineering in the University of Pennsylvania. It was the first of many firsts for the duo, an electronic computer that quickly earned the nickname of “Giant Brain.” The speedy device was 1,000 times faster than other machines, then at an astronomical cost of about $500,000. It drew immediate national attention during World War II and went on to help the U.S. Army that summer of 1946. Parts of the original model are still on display today at the ENIAC Museum in the University of Pennsylvania.

Presper Eckert was a Germantown native. He placed second in the country in math on the college boards. His first patent, “Light Modulating Methods and Apparatus,” came at age 21. He was then assigned to Mauchly’s ENIAC project, and the rest was history. The two left the Moore School over a dispute for the ENIAC patent. The University of Pennsylvania wanted to claim the device as its intellectual property since it had sponsored Eckert and Mauchly’s work. The young entrepreneurs managed to maintain patent rights.

Mauchly and Eckert were not done. With a team of design engineers, they founded the Eckert-Mauchly Computer Corp. in 1948. They settled at the Ridge Avenue address and got to work. It was here that the Binary Automatic Computer (BINAC) was born on April 7, 1949. The user-friendly machine had a memory capacity of 1,024 words. It was purchased in 1949 by the Northrop Aircraft Co.

The former BINAC site, now the Marketplace at East Falls.

A year after Jeff and Lisa Baskin decided to buy the site for the Marketplace, they learned of the space’s important history. While renovating, they were contacted by Peter Cook, a professor of computer science at Temple who worked with Cook and a group of retirees, who worked on Universal Automatic Computer (UNIVAC)  to add the historical marker outside. It took two years to receive approval for the marker, which was celebrated with a ceremony in 2006.

“We wanted to give John Mauchly and J. Presper Eckert their due,” says Lisa Baskin, “Recently, Mauchly’s grandsons contacted us to reconstruct the computer as it was in 1948 and show it at the Marketplace. They are raising funds for that now.”

Inside the Marketplace


Eckert and Mauchly weren’t just building BINAC at the time. They were also working on another computer–one that would outperform any computer they had built and would recall data from memory and use an input device modeled after a typewriter keyboard. It was finished in 1951 and became the world’s first commercial computer. They sold 46 computers to the government and other buyers.

It is these accomplishments that Mauchly’s grandsons, Jim and William Reed, would like to commemorate. Jim currently runs a Web site called EniacMuseum.com. William is co-owner of two well-established Philadelphia pubs, Johnny Brendas and the Standard Tap. His uncle, Bill Mauchly, also has a Web site devoted to the history of the ENIAC.

“I was only 12 when he [grandfather John Mauchly] died,” recalls William Reed, “So we never shared a beer. He had a baby grand piano in the front room of a rambling old stone house called Little Linden. They had a wing added to the house to accommodate my grandfather’s computers. He had a network of terminals in the house [in the ’70s] and we all grew up thinking that was pretty normal. The computer was hooked up to the precursor to the Internet, and a large tractor feed printer would jump to life at any moment.”

It wasn’t just computer science that dominated Mauchly’s days. He was remembered as being a single-malt scotch drinker and a family man, in addition to his scientific contributions. Reed says that Mauchly’s passion wasn’t limited to the machines he was known for or the parties that he hosted every Christmas.

“John Mauchly was a physicist first, and he would sometimes be sending a colleague ideas on weather prediction or large prime numbers. He would read ‘Scientific American’ and not just get it but send notes to authors with his own ideas on the subject they wrote about. The word ‘genius’ is a bit devalued today, but I don’t have a better word for him,” Reed says.

Eckert with his model for a desktop computer. photo: Dan McGrath

Only five to six UNIVACs were actually made at the site at Ridge Avenue before production was moved to 23rd and Allegheny Avenue. In 1952, after the company had been sold to Remington Rand, the Ridge site saw a final groundbreaking moment: CBS decided to broadcast results from the presidential election, using UNIVAC to predict the outcome. It is documented that Walter Cronkite and CBS programmers were skeptical of the UNIVAC predictions and gave out different numbers from the ones that the computer had provided. UNIVAC ended up being more accurate than the manual prediction, only four electoral votes off count.

The next time you pass 3747 Ridge Ave., look up from your smartphone and give a nod. In the face of many odds, in a time of no venture capitalists, two local men did the unimaginable, and their influence extends far beyond this neighborhood.


  1. Very good read. I just wonder after reading your post and other history related posts – why aren’t these great minds only prosper in the past? We could really use some of them in our society today.

    Andrew of Intervention

  2. Hi – I moved from Philly a year later and never knew I was mentioned in the article until now. It was a honor working to make this happen.

2 Trackbacks / Pingbacks

  1. ENIAC: What is the future of preserving Philadelphia’s super computer legacy? [Video] — Technically Philly
  2. physics laws

Leave a Reply

Your email address will not be published.