I’m a little late for today’s class and I will be leaving a little earlier as well, so the notes for this class may be just a tad bit incomplete (not like the notes for the rest of the lectures were //perfect//!). Of course, today’s class is special because we have the legendary [[wp>Gordon_Bell|Gordon Bell]] as the guest speaker.

Bell started by giving a brief overview of the four main themes of his talk: Moore’s law and Bell’s law, commoditization of technology and computer generations, DEC and minicomputers.

The first couple of slides are on DEC itself. How it was born out of MIT’s Lincoln Lab with some VC like funding from American R&D. The business plan was to design, manufacture and sell logic modules and use earnings to build computers. DEC was legendary in its time for quickly adapting to the rapidly changing technology. Note that in those days the //hardware// was rapidly evolving — these days companies struggle to keep up with just the //software// changes. DEC survived the coming and going of microcomputers, integrated circuits leading to VLSI and so on. And of course DEC made the PDP (Programmed Data Processor) series, without which we probably wouldn’t have had UNIX :)

(//Aside//: I don’t like Mr. Bell’s slides all that much. Too much text, the slides lose focus. And what he says for each slide doesn’t really highlight any focal point in each slide.)

The first PDP was delivered to BBN. The PDP-6 had timesharing. DEC also built the VAX (//Virtual Address eXtension// to the PDP-11), which was one ofthe first systems with a concept of //virtual memory//. Its surprising that DEC was around as late as 2002 — I somehow don’t remember hearing a lot about DEC. Compaq (now HP) acquired DEC in 1992.

The next couple of slides talk about the PDP-1, the PDP-5 etc in a little more detail. Nothing particularly insightful here — mostly factual details and some interesting anecdotes. PDP-1 had 18-bit words and a 4-kilo word capacity. PDP-5 had 12-bit words. So we can still that there was no sense of a platform or architecture or instruction set at that time. PDP-6 (the timesharing super-machine) could serve 128 terminals at once, and had a peak memory capacity of 262000 words.

PDP-11 was 16 bits (here we see the magic number 8 coming up) and VAX was one of the first 32 bit computers. Recall that IBM 360 sort of established the 8-bit byte convention. Before that it was all very ad-hoc.

The “mini-computer” actually denotes the //minimal//-computer: take the current technology, and combine it into a package with the smallest cost (so more like a bare-bones system in today’s parlance).

**Bell’s law of Computer Generations (or “classes”)**

Classes of computers form and evolve just like modes of transportation, restaurants etc. Governed by a lot of economic based laws such as the “network effect” or learning curves or the marginal cost of hardware/software etc. We’ve had the following classes so far: building sized computers, main frames, minicomputer, workstation, PC, laptop, PDA, sensor motes? How will future computers be build? **Scalable Networks and Platforms**.

Every decade a new class emerges, which has an order of magnitude better cost-performance ratio. New classes lead to new apps lead to new industrijes.

Alright time to take off now. I’ll be missing the VAX strategy onwards part of the class. Probably will fill in later after consulting the wiki. Cheers!