Ancient
The history of computational devices is much longer than the history of modern computers, and the New Computer Museum includes an exhibit near the entrance about this history. Of course, among other things, there is a sliderule.
Here is a YouTube video that explains the many calculating devices that were around before the computer was invented.
Here is an image of the Antikythera mechanism that you will see hanging on a wall near the entrance to the New Computer Museum.
Here is a YouTube video that explains the history and function of the Antikythera mechanism.
Related page on Cosma.org: computing devices — Antikythera, slide rule, Babbage, etc.
Slide Rule
Of course, before our modern digital computers, there was the beloved slide rule!
The New Computer Museum has a few special slide rules to display as well as a table of slide rules and instructional materials about them available for visitors to use.
Related sites
Simulated Pickett N525-ES StatRule Slide Rule
Derek’s Virtual Slide Rule Gallery (Derek Ross)
Virtual Slide Rules (Derek Ross)
Slide Rule History (HP Museum)
International Slide Rule Museum (Mike Konshak, Louisville, Colorado)
Genealogy
Although computing goes back to the Chinese Abacus—or the Japanese version, the Soroban—the roots of modern computers are found in punch card equipment, particularly its ancestor, the Jacquard loom, which may have operated in the DEC mill at one point. Calculators were built by mathematicians Pascal and Leibetz, but modern mathematicians have given up computer design – leaving computers to engineers. Though calculators are historically and technologically interesting, they’re really dull in comparison to the modern stored-program computer, which gets its power by variable programs, with the ability to calculate rapidly, hold lots of information and even learn. — Gordon Bell (Computer Generations, Digital Equipment Corporation Museum Project, 1975)
This poster from The Computer Museum that shows the evolution of calculating devices up to and including the first modern computers now hangs in the New Computer Museum.
Related page on Cosma.org: Calculator History — Pascal, Leibnitz, Jacquard, Hollerith, etc.
Mark I, Working! (Video)
The IBM Automatic Sequence Controlled Calculator (ASCC), which was dubbed Mark I by Harvard University’s staff, was a general purpose electro-mechanical computer that was used in the war effort during the last part of World War II. It now sits in a relatively public space in the Science Center at Harvard University in Cambridge, MA.
Here is a video in which Professor Harry Lewis takes the class CS50 on a tour and explains a bit of the anatomy and history of the Mark I.
The Mark I received a major renovations not too long ago, and the public was invited to attend a special ceremony in which it was even turned on April 3, 2014. Attending that event was one of Mary Hopper’s most interesting adventures since she began the New Computer Museum.
This video of the Mark I running that was shot by Mary Hopper and narrated by Alan Wu.
Best of all, The Computer Museum held a series of lectures and videotaped them back in the 1980s, and now they are posted on YouTube, so you can hear the story of the Mark I from Grace Hopper herself!
Related posts
Mark I Turned on and working! (April 2014)
Winter fun! (Walter Isaacson’s visit to Harvard, December 2014)
Related sites
Harvard Mark I exhibit gets an upgrade (Alvin Powell, Harvard Gazette)
Here’s looking at you, kid! (The Collection of Historical Scientific Instruments, Harvard University)
Grace Hopper, computing pioneer (Walter Isaacson, Harvard Gazette, December 3, 2014)
Howard Aiken (Computer History Museum)
Harvard Mark I (Columbia University)
Harvard Mark I (Britannica)
Harvard Mark I (Wikipedia)
Pioneers Posters & Videos
The video of Grace Hopper’s lecture included above was just one among many lectures in wonderful series that explored the invention of the computer in great depth. The Computer Museum hosted a historic series entitled Computer Pioneers, and a series of posters were created as advertisements for that series. The actual physical posters were donated to the New Computer Museum by Brian Silverman, and they hang on the walls of the New Computer Museum and serve as links to the corresponding videos of the lectures on YouTube. There is also a page on The Computer Museum’s site that describes the lecture series and links to the videos. The Computer Museum: Videos
Here is a two part video on YouTube of a lecture by Gordon Bell that provides an overview of the history covered in the series.
Here is an extremely helpful image from Gordon Bell that shows the relationships among the earliest computers discussed in the series, and it is also hanging in the New Computer Museum. It originally appeared in the booklet authored by Gordon Bell entitled Computer Generations that was published by the Digital Equipment Corporation Museum Project in 1975.

NSF Computer Tree Graphic, Bell Additions (Click to see the picture and use built-in tools to magnify it.)
Be sure to check out Pioneers Posters and Videos page to see all of the lectures and learn all about how computers were invented!
Related sites
Revolution: The first 2000 Years of Computing (Computer History Museum) Topics & Timeline
Birth of the Computer (Computer History Museum)
Memory & Storage (Computer History Museum)
Inventing the Computer (Engineering and Technology History Wiki)
The History of Early Computing Machines, from Ancient Times to 1981 (Vincze Miklós)