[etoys-dev] Toy computers

[Jecel Assumpcao Jr.]

David,

the problem with your plastic logic toy was that it had a single level.
Simple projects were simple and understandable, but more complicated
ones would get out of hand. In the same way, I feel that the solution is
to have a sequence of Etoys projects where what you build in one is a
basic block in another. You can either go bottom up (better for concrete
thinkers) or top down (abstract thinkers like this).

Here is a college level course that does this:

http://www.cs.huji.ac.il/course/2006/nand2tet/

http://www.youtube.com/watch?v=JtXvUoPx4Qs (10 minute video)

http://video.google.com/videoplay?docid=7654043762021156507 (61 minute
video)

Starting with NAND and building everything on that is cute from a
mathematical viewpoint, but it I would start by showing the basic gates
in terms of switches and lamps (there is an Etoys project for this, I
think) or in terms of colored rectangles for CMOS chips (perhaps this
could be done in Kedama in a reasonable way).

Their processor is really pathetic, but they only use it to implement a
Java-like virtual machine and then use that from then on. The Squeak VM
could be used as an alternative, but it is very complicated compared to,
for example, the one in Little Smalltalk.

Chuck Thacker's TinyComputer designs are simply wonderful, but by
implementing it as a very compact Verilog description there is just too
much magic for someone who hasn't seen the logic gates and lower levels.
There is no reason not to implement it as a schematic, however.

I have a very long list of educational processors you can look at, if
you want. Some have been implemented in TTLs, others in FPGAs and still
others just as simulators running on PCs. Here is one of my favorites:

http://www.bradrodriguez.com/papers/piscedu2.htm

-- Jecel