Via Digital Trends, the first computer had a strange, fascinating beginning.

Its construction in the 1940s marked a major milestone in computing’s early history, being involved with research into the hydrogen bomb. It’s celebrated every year on February 15 (ENIAC Day), but it’s just as appropriate to pay it some attention during Women’s History Month in March.

The job of programming ENIAC, the first computer, fell on a team of six young women. Their contribution to its success was largely glossed over in the years that followed, but all of that has changed. The truth about how the first computer was programmed is a story of that needs to continue to be retold.

Despite the trailblazing work the six women did, they’re likely not names that you’re familiar with. Back then, computers were programmed through a physical system of adjusting switches and cables manually — debugging a program meant climbing inside the ENIAC in search of faulty connections. A new program had to first be sketched out on paper, then implemented with extreme precision. Setting up a single calculation could take days, and a full program could take weeks.

See the videos below for some insights from and about these amazing pioneering women and read more here.