Connection machines were a line of parallel supercomputers built by Thinking Machines Corporation. Notably Stephen Wolfram and Richard Feynman were involved in the early years of the corporation.
Here are some delightfully academic and stiff Thinking Machines Corp. promo videos from Youtube. The first one features some great footage from a lattice gas automata fluid dynamics model (I can’t believe it took a person year for the LGA model, I put one together in a week or so on MATLAB. My ego is pleased.)
Ironically Thinking Machines Corp. went bankcrupt in 1994, when parallel computing is a hot commodity today in 2009.
I want to write a little bit more about my studies on waves and automata models. I wrote a vastly improved TLM code on MATLAB which now includes for example first order absorbing boundaries. It is important to distinct this approach from a mathematical model, this is a analogous physical system to wave propagation. You could think of it as using computer memory element grid as an discrete analogy to the vacuum.
This sort of physical modelling and computation was first used by a Hungary born mathematician and electrical engineer Dr. Gabriel Kron in 1943 while working for General Electric (see paper called ‘Equivalent Circuits to Represent the Electromagnetic Field Equations’ on Physical Review Vol.64 Numbers 3-4 1943.) The approach involved analog computing in the form of a RLC network. The approach was then picked up by P.B. Johns and R.L. Beurle (see paper ‘Numerical solution of 2-dimensional scattering problems using a transmission-line matrix’ on Proc. IEE, Vol. 118, No. 9, 1971, pp. 1203-1208) applied to ‘computors’ as they were then called.
The Johns and Beurle numerical method involves applying a simple scattering automata rule to a discrete node grid. This doesn’t exactly involve integration in the sense that a discretisized mathematical model would; only arithmetic needed is addition (floating or fixed-point) for summing up the node incidence and reflection time-step impulses involved in the scattering rule (which are directly derivable from normalized unitary impedance electrical node network.)
The simple TLM here is configured for the classic Young double slit experiment. Although this particular setup could be thought to just propagate the electric field, the corresponding magnetic field can be derived aswell together with different permittivity and permeability coefficients to model material properties.
Visited a small retro gaming event this weekend and came home with some cool new vintage computing junk. In particular I finally got hold of a Commodore Vic-20. This was my first computer back in the eighties so it holds a special place for me. It is in good condition, even has the first(?) ceramic revision of the VIC video chip. However it’s not the model that takes the C-64 type of power supply, instead it has a two prong connector which should feed the vic with 2 amps worth of 9 volt alternating current. I had some 9V ac wallwarts laying around so I decided to try it out if the thing is in working condition.
Turns out that the wallwart rated at 1A isn’t enough for the circuitry, or alternatively the VIC chip or something along the address bus decoding is busted. I’m guessing it has more to do with the power supply, since probing with a scope revealed that the TTL glue logic responsible for the VIC address decoding is stuck at around 2 volts.
The glitching causes interesting visual patterns though!
