FPGA VAX update

[Chuck Guzis]

On 11/2/2005 at 6:31 PM Allison wrote:

>Valves are harder due to power, heat and most importantly size. A few
>hundred
>miniature duo-triodes will fill several racks.

I used to buy old mil-surplus boards that each contained six wired-in
subminiature (Raytheon CK something or the other) dual triodes--no sockets,
the tubes were equipped with wire lead bases and were about the size of
those suminiature tubes in the old Motorola Pixie radio.  At the time, I
wasn't that interested in computers, but the triodes made for some great
VHF circuits.

What surprises me about the home-built computers from scratch is the lack
of imagination when it comes to architecture.  Most are basically
one-address-cum-accumulator designs.  It would seem that larger register
files are much easier to build nowadays and would open up the door to some
2 and 3-address designs.  

I've always thought that 24 bits is a nice word size for a small computer.
Divisible by 2, 3, 4, 6, 8 and 12 bits.  An instruction could use 6 bits
for opcode and 3 register addresses out of a 64 register file...

Variable word length, dataflow, all sorts of possibilities--why be limited
by implementing something that resembles an already existing machine?

But then why go to the trouble of wiring the thing up?  Write a
simulator--it'll probably run faster anyway.

Cheers,
Chuck