Microcircuits and the future

Its been awhile since I’ve posted about anything from Modern Mechanix, but recently he posted an interesting article from Time Magazine about “The Computer Society.” Published in 1978, the special section contained several articles about the specifics of the new microprocessor revolution going on, including a fascinating look at early “smart home” automation work and a discussion of how deeply computers will extend into our lives. One of the most fascinating aspects of the article is how accurate the predictions are in some cases … ““In schools, computers will be more common than carousel slide projectors, movie projectors and tape recorders. They’ll be used from the moment school opens, through recess, through lunch period, and on as far into the day as the principal will keep the school open.”” While that may seem to a common sense observation from the perspective of 2007, its hard to overstate how revolutionary the notion of schoolroom computers was in 1978. At a time when there was a huge debate about the use of basic pocket calculators, the idea that students might use computers “from the moment school opens, through recess, through lunch period, and on as far into the day as the principal will keep the school open” was seen by some as unthinkable.

But what really caught my eye wasn’t any of the articles, but rather the “Letter from the Publisher” where they introduce their newest staff member, PDP-11/34. The first computer I ever worked on, professionally, as a well-log digitizer in Calgary for QC Data Collectors in 1985, was a PDP 11/34. There was also an 11/70 as well as a VAX 11/780, and while the VAX ended up being where I spent most of my time at QC (and was actually the experience that sent me to Africa a few years later), the PDP 11/34 was my first introduction to computing in a professional sense.

While the machines look quaint and obsolete from 2007, the 16-bit architecture and Unibus design were revolutionary for the time. The Unibus design was a radical change from previous designs that used dedicated I/O buses to deal with input and output devices. These interfaces were generally difficult to implement because of the need for specialized I/O based instruction sets in addition to the memory based instruction sets already required. As well as increasing the complexity of implementation and use, the dedicated bus design also tended to be “bulkier” from a code perspective because of the “duplicated” instruction sets. The Unibus design put all I/O on the same bus system as memory operation, which allows programmers to address I/O devices through memory address mapping using the same instruction sets they use for regular memory operations, greatly streamlining the code, and ultimately, operations in general. The Unibus design paved the way for modern computers and “plug and play” peripherals in a very basic way … the ease of use we currently see in peripherals wouldn’t be possible in an architecture based off a dedicated I/O bus. In that way, at least, the PDP 11 marks one of the birth places for what we call the modern computer.

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