TTL computing

From: Richard Erlacher <edick_at_idcomm.com>
Date: Sun Apr 14 20:10:45 2002

The easy part is the socket ... If you get a PGA socket for the 84-pin PLCC
socket and plug the PLCC socket into it, your problem is solved. The PGA
socket once was very common, but, though it isn't any longer popular, it is
still quite avaialble.

I personally used the "back" portion of a wirewrap card for the PC/AT, made by
Vector, that had 0,055" holes drilled for wire-wrap pins. I had a number of
old wire-wrap boards with only 16-pin footprints, from Garry Mfg, and one
weekend, while waiting for a repair of my prosthesis, I knocked out aout 5000
such pins from a bunch of boards. I simply insert them in the holes, and they
make up a socket in whatever pattern I desire. There are several mfg's who'll
supply you with those pins if you're willing to pay the price. The cost,
ISTR, seems to hover between $0.10 and $0.15 per pin, which price is generally
beaten with the adapters if you buy them already made up. Companies like
Aires and Emulation Technology, though there are several more that I'd look at
before buying, since both of these are pretty pricey. If you get a part
number from Aires and E.T, nearly anyone else will be able to tell you right
away whether they can supply an equivalent.

More below ...

Dick

----- Original Message -----
From: "Ben Franchuk" <bfranchuk_at_jetnet.ab.ca>
To: <classiccmp_at_classiccmp.org>; <fpga-cpu_at_yahoogroups.com>
Sent: Sunday, April 14, 2002 9:00 AM
Subject: Re: TTL computing


> Richard Erlacher wrote:
>
> > If you buy a moderately cheap CPLD, e.g. the XILINX 95108, in a PLCC84, it
> > costs about $20-30 U.S. at DigiKey. Combine that with a socket, ($4 tops)
and
> > a few wirewrap socket pins, ($.10 each) that's another $8.40. Now find a
> > cheap wirewrap board to which you can solder ... and then use the free
> > software and build the ~$5 ISP adapter.
>
> Has anybody done that?
>
I personally used the ALTERA ISP adapter that was sent to me as part of a
sample kit together with a crosspoint switch with which I manipulate the
positions of the signals in order to make up the differences between signal
assignments from one applicaiton to another. I don't remember that I had to
use it, but it was plugged in. There are, after all, only so many signals
that you can manipulate.
>
> > For the same money, you can use a
> > Xilinx SPARTAN-series FPGA which you can also program using the ISP
> > programmer, though you'll have to do it every time. Then you can design
> > pretty much whatever small computer (only because of pin-count
limitations)
> > you want. These devices even allow you to put in some RAM.
> >
> I have a nice FPGA prototype kit, (altera) but I am having problems
> getting A PROM for it. I may go to using smaller chips like the XC-9572
> (72 macro cells) ? $12 canadian. They don't make wire wrap PLCC sockets
> (or not in DigiKey) so I will end up with making a PCB. I have a new CPU
> design and expect about 10 CPLD's in total.
> --
Both manufacturers seem to believe that you can program their FPGA's from the
parallel port without any sort of prom. I've not yet seen a clear description
of how to do it, though. It probably treads on their programming technology
which they think is "secret."
>
Received on Sun Apr 14 2002 - 20:10:45 BST