In the last four decades, the world of computing has seen its share of legendary computers, and if there is one that deserves special attention, it is the Xerox Alto. Launched in March 1973, the Xerox Alto was the first commercial computer controlled with a graphical interface. The YouTube channel CuriousMarc gained access to the process of restoration of a Xerox Alto, which will lead to the verification of every detail in a computer older than the writer of these lines.
A Machine Ahead of Its Time
Several sources describe the Xerox Alto as "the first modern desktop computer". Usually, that description falls on the IBM PC, but history shows there were more than eight years between the two. Needless to say, the Xerox Alto targeted a very different market. We are talking about an era when the concept of "computer" was limited to laboratories or special shared-use environments. The idea that gave shape to the Xerox Alto was developed in a document by scientist and PARC administrator Butler Lampson (thanks to the magic of the Internet, we can read it), and was inspired by the NLS system designed by none other than Douglas Engelbart, the inventor of the mouse. Charles P. Thacker (one of the inventors of what is now known as Ethernet) became project leader, and after giving the green light to an experimental series of 80 units (at an approximate cost of $10,000 each), the success of the Xerox Alto was such that about two thousand additional computers were built in the following ten years.
A Visit That Changed Everything
However, the Xerox Alto holds another special place in history as the system that Xerox employees showed to Steve Jobs during his famous visit to the company in December 1979. The mouse-controlled graphical interface on the Xerox Alto (or WYSIWYG technology, "what you see is what you get") directly influenced the development of the Apple Lisa and, a year later, the Apple Macintosh. Just by opening the Xerox Alto, one can conclude that it was a wonderful piece of electronic engineering in 1973. The Alto has thirteen PCBs, three of which (Control, ALU, and RAM) represent the processor. The available RAM was 128 kilobytes, expandable to 512 kilobytes, but that was not a decision to be taken lightly, since each 'block' of 128 KB had a price close to four thousand dollars.
The Restoration Challenge
The mission to restore a Xerox Alto is titanic even for those with the knowledge and necessary equipment. In addition to the computer's age, we must also add its complexity. The Alto requires a total of four power supplies, providing -15, +15, +12, -5, and +5 volts simultaneously. The power supplies demanded careful evaluation, using "dummy loads" and a variable transformer. Worn-out capacitors, corrosion, deteriorated previous repairs, a CRT tube over 40 years old, and a good dose of trial and error will surely bring this historic computer back from the dark side. It is worth following its progress.
