Restoring and Demoing 1960s Vintage Computers at the Computer History Museum [pdf]

Restoring and Demonstrating 1960s Vintage Computers at the Computer History Museum Robert Garner IBM 1401 Restoration Project Lead, Computer History Museum Abstract: Beginning in 2003, the Computer History Museum in Mountain View, California, sponsored long-term projects to fully restore and demonstrate three large 1960s vintage computers: a DEC PDP-1 and two magnetic-tape IBM 1401 systems. By 2005, a small volunteer team of engineers had restored the PDP-1. By 2010, another volunteer team of over a dozen retired IBM customer engineers restored two 1401 systems plus various unit-record equipment. In 2013, the museum opened two public demonstration labs to showcase the restored computers: in the DEC PDP-1 Demo Lab, visitors can pit dueling Spacewar! spaceships against each other on its cathode ray tube display. In the IBM 1401 Demo Lab, docents invite visitors to keypunch their names into punched cards that are then printed on its lively line printer. In this paper, we cover the restoration of the 1960s systems, how they are demoed and used, restoration logistics, ingredients for success, and conclude with thoughts on “Why restore and demo vintage computers?” Introduction Museums help shape the identity and character of a community by preserving and curating artifacts, chronicling key accomplishments, and presenting the human stories that underlie them. Our belief is that a technology museum can dramatically enrich its visitor experience by exhibiting and demonstrating authentically restored and operational vintage computers. Nevertheless, museum staff may feel unprepared to take on the challenges of a vintage computer restoration and demo project. What are the ingredients for a successful project? In this paper, we present an account of the successful restoration and demonstration of three 1960s vintage computers at the Computer History Museum (CHM). The CHM’s mission is “to preserve and present for posterity the artifacts and stories of the Information Age” while bringing the history of computing to life via public exhibits, educational programs, volunteer docent-led tours, speaker series, national media and radio programs, and community outreach. In 1979, the museum, then located in Boston, began assembling what is now the largest collection of computing artifacts in the world.

In 2002, the CHM moved into its current facility at 1401 N Shoreline Blvd, Mountain View, in the heart of Silicon Valley. As the staff began strategizing on goals and exhibits, including plans for a flagship exhibition on computing history, a passionate volunteer petitioned the staff to shepherd a volunteer-driven project to restore and demonstrate a 1960s large vintage computer, believing that it could enrich the visitor experience. In this paper, we summarize the CHM’s two volunteer-based projects that restored three large 1960s vintage computers: a DEC PDP-1 and two magnetic-tape IBM 1401s.1 We also discuss how they are regularly demonstrated and their on-going usage. We conclude by recommending 1 Beginning in 1998, CHM volunteers earlier restored an IBM 1620, “a prototype of a successful artifact intervention” (Spicer, 2005). It is no longer demonstrated to visitors, mainly due to the absence of compelling peripherals. Another team has restored a vintage IBM 350’s fifty-platter stack and servo access arm — the world’s first commercial disk drive — demoed every Wednesday in the Museum’s main Revolution exhibit.Proc. Making IT Work, 22-23 May 201754 Restoring and Demonstrating 1960s Vintage Computers at the Computer History Museum ingredients for a successful restoration and demonstration project and our thoughts on “Why restore and demo vintage computers?” Restoration of a DEC PDP-1 from Massachusetts A restored vintage computer should offer a compelling visitor experience. In 2003, volunteers recognized that the DEC PDP-1, an early display-based interactive computer, would fulfill that objective. In particular, visitors could play the legendary Spacewar! video game on its large cathode ray tube (CRT). Spacewar!, an expression of the 1960s MIT hacker culture that shaped the early days of computing, was arguably the inspiration for the video-gaming industry. While only 55 PDP-1s were produced, they had a prominent presence at leading universities, including MIT, Harvard, Yale, Columbia, and Stanford.

Selecting between the three in its collection, the museum elected to restore a PDP-1 it had acquired from a small Boston firm in 1978. Starting in 1962, the firm had rented it out for human-machine research, such as investigating interface designs in early electronic word processing. Beginning in 2003, meeting once a week in a CHM conference room, a small volunteer team of engineers restored, over two years, its transistor-based CPU mainframe, point-plot Model 30 CRT display, paper tape reader, and Soroban console typewriter (Bickley, 2007). Applying standard practice to its old power supplies, the restoration began by reforming their electrolytic capacitors.2 The main challenges were the finicky CRT deflection amplifiers and the console typewriter. The team elected to substitute contemporary power supplies for the CRT’s 10 kV anode and the light pen’s 1 kV photomultiplier tube. A local typewriter repair shop was happy to take on the console typewriter. Only four printed circuit cards — DEC System Building Blocks — were found to be faulty. To enable visitors to play Spacewar!, the team built two button-actuated control boxes mounted on the exhibit railing (Figure 1). The PDP-1 was fully operational and ready to demonstrate by 2005, when the team began giving weekly demonstrations. The following year, it was moved to a room just around the corner from the main entrance. The back wall has a large vintage photograph of engineers attending to a PDP-1 in DEC’s Maynard, MA facility. A looping video inside conveys the historical significance of the PDP-1 and Spacewar! (Plutte, 2014). Figure 1. Volunteer and Spacewar! author Steve Russell gives a live demo in the DEC PDP-1 Demo Lab 2 After removal, a programmable power supply slowly ramps up the applied voltage on a single capacitor (while safely limiting current), redepositing a natural oxide layer on its positive plate.Proc. Making IT Work, 22-23 May 201755 Robert Garner The PDP-1 is demoed on the first and third Saturdays of every month and Spacewar!

tournaments are held quarterly (Russell, 2011; Verdiell and Bickley, 2017). Volunteers speak to DEC’s lab instrument and computer business and demo the mesmerizing Snowflake and Minskytron CRT drawing programs. They next invite visitors to pit dueling Spacewar! spaceships against each other on the ghostly long-persistence phosphor CRT using the push-button control boxes. As an invaluable historic tie-in, two team members are Spacewar! authors. Another of the original MIT hackers presents the PDP-1 playing transcoded Bach scores in four-part harmony. Every December, continuing a vintage MIT tradition, a sing-along features the PDP-1 playing synthesized holiday music. Restoration of an IBM 1401 from Germany In 2003, while participating in the PDP-1 restoration, we became aware of an IBM 1401 listing on the German eBay. As many people had strong memories of 1401s — the world’s most popular computer in the mid-1960s — the museum staff and volunteers felt that it would offer a compelling vintage computer demonstration. Visitors could keypunch cards, experience its lively chain printer and see spinning magnetic tape drives — the iconic face of computers in the 1960s. With over 15,000 installed worldwide, the business-oriented 1401 Data Processing Systems were an inflection point in computing history, leading the IT industry’s transition from decades of unit-record equipment and accounting machines to an era of ubiquitous and more flexible stored-program computing. For many, the 1401 was their first experience with hands-on programming (Garner and Dill, 2010; Garner, 2013a). When I volunteered to lead the project, my first question was “What is an IBM 1401?” When IBM announced it in 1959, I would not even have been tall enough to reach its control panel. Intrigued with the challenge of bringing a large 1960s vintage computer back to life and, having joined IBM Almaden Research in San Jose, I was curious about IBM’s computing heritage. (My nascent computing experiences were on DEC, SDS, Univac, and GE systems.)

But first I had to find volunteers with the hands-on instinct and experience to tackle the mechanically rich equipment. Following a tip, I placed an “An IBM 1401 Needs Help” ad in the region’s IBM San Jose Retirement Club newsletter. Within a month, over a dozen retired IBM customer and manufacturing engineers stepped forward to help with its restoration (Garner, 2013b; Ross, 2009) — see Figure 2. The German 1401, which we designated as the “DE 1401”, was built in 1964 and operated by an insurance company 24x7 for eight years. In 1972, an entrepreneur procured it for his family service business in Hamm, Germany. In 1977, he mothballed it in a detached automobile garage for 27 years. After arriving at the museum in 2004, the new team of about a dozen volunteers rallied to meet the challenge with a spirit of commitment and determination. Many had been IBM Customer Figure 2. IBM 1401 volunteer restoration team, vintage attireProc. Making IT Work, 22-23 May 201756 Restoring and Demonstrating 1960s Vintage Computers at the Computer History Museum Engineers responsible for keeping businesses up and running 24x7 from the 1950s onward. Some regarded the CHM as yet another mission-critical client, but fortunately without the stress and pressure of needing to get a customer’s system back up and running ASAP. The DE 1401 came with over a dozen units: 1401 CPU mainframe, 1406 extended core memory, and its electro-mechanical peripherals — 1402 card reader/punch, 1403 line printer, six 729 tape drives — along with various 1940s unit record equipment — several 026 key punches, 083 sorter, 077 collator, and a 513 reproducing punch. Luckily, the museum’s facility had a 1,400 square-foot raised- floor server room that could accommodate the 12-kilowatt load, workbenches, test equipment, and volunteers.