TTL computing

From: Christopher Smith <>
Date: Fri Apr 12 17:11:21 2002

> -----Original Message-----
> From: []

> Here's how I'd do it (to make an 8 * 1 bit fusible-fuse PROM).


> The way it works is like this. Normaly the Rd/Pgm relay is in the Rd
> state (as shown). In which case the sense relay is energised if the
> selected fuse is intact. You can use the contacts of the
> sense relay to
> turn on/off a light bulb or something.

Very close to what I imagined doing -- though, I hadn't gotten as far as
an address decoder. :) Thanks.

> To blow a fuse, select it with the decoder tree and then energise the
> Rd/Pgm relay briefly. Enough current will flow via the
> limiting resistor
> to blow the selected fuse. When the Rd/Pgm relay returns to
> the normal
> position, there will no longer be a path to ground for the
> bottom end of
> the sense relay, so this relay will not be energised.

Again -- a good plan. I was thinking about using a momentary switch
for programming anyway, rather than anything more complex, so that
fits exactly with what I wanted.

> I am going to _have_ to make one of these just for fun....

I'm glad that I'm not the only one crazy enough to consider trying it.


Christopher Smith, Perl Developer
Amdocs - Champaign, IL

/usr/bin/perl -e '
print((~"\x95\xc4\xe3"^"Just Another Perl Hacker.")."\x08!\n");
Received on Fri Apr 12 2002 - 17:11:21 BST

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