Build your own Apollo Guidance Computer
shoppa_classiccmp at trailing-edge.com
Mon Jan 1 06:24:08 CST 2007
Richard <legalize at xmission.com> wrote:
> In article <45981727.2040705 at jetnet.ab.ca>,
> woodelf <bfranchuk at jetnet.ab.ca> writes:
> > Richard wrote:
> > > Is it even possible to build with RTL parts anymore?
> > >
> > > I guess you'd have to do it PDP-8 style with discrete transistors?
> > Well I don't like the FPGA idea -- TTL/DTL/RTL logic is still
> > visible logic. What good is FPGA's if the windows gets updated and
> > the FPGA software is not supported. PALS and GALS I could see used.
> Sense not making, you.
I have hand-programmed PALs all the way from pencil-and-paper logic to
putting the right volts on the right pins and hitting a one-shot to
do the fuse-blowing. No computer necessary at all. It was decades
ago but I did it!
Non-registered PALs can also be reverse-engineered without any
fancy tools (although I'll admit that I usually use a computer to
do so, a couple times I have found all the possibilities for
"what address does this thing decode?" with just some 7493's and a 555.)
Now all that probably could be done for GALs and even FPGA's but
I haven't done that :-). Even most GALS do not have publicly released
I will gladly admit that the "moral equivalent of the visible PAL" is
the guy who built a processor from discrete surface mount parts
where the "programmable logic" was using/not using arrays (of diodes?
most likely) of parts on pluggable PCB's.
Don't have the URL handy and Google isn't helping. End result seemed
to be more compact and functional for homebrew processor purposes than
DIP PAL's, and a lot more visible.
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