There are packaging options which might be utilized to help you in "scoping"
out your circuit. One of many complaints I have about FPGA's is that they
have far too many pins to suit me. Well, since there are lots of pins, you
can obtain a socketable adapter for the package and then work your way
through the design, changing the "bond-out" by routing the signals you want
to compare to I/O blocks associated with otherwise unused pins. That way
you might be able to help yourself figure out strange timing effects between
internal and external signals, perhaps even allowing you to see the inner
workings at least to some extent.
The handiest package I've run into for these is the PLCC84, for which you
can obtain a socket compatible with a wire-wrap adapter. That would allow
you to do what I described above without interfering with the 40-odd signals
you might want to inject into your existing application. This same thing
might be achievable with a larger package, but I have some doubts about
making the transition from the FPGA package to a wire-wrap socket. You
might have to make an adapter PCB or buy one from Samtech or Emulation
Technology. Those get expensive.
Dick
-----Original Message-----
From: allisonp_at_world.std.com <allisonp_at_world.std.com>
To: Discussion re-collecting of classic computers
<classiccmp_at_u.washington.edu>
Date: Monday, August 30, 1999 12:03 PM
Subject: Re: FPGAs and PDP-11's
>
>> They're wide PDP-8s. Or rather, the PDP-8 is a narrow PDP-4.
>
>I know that! ;) what I don't know is all them little details I know so
>well for PDP-8.
>
>> > I would want a machine that would fit in nx4 or nx8 format parts.
>>
>> Doesn't particularly help if you're putting it in an FPGA.
>
>Why would I want to use them... &-) I was thinking interms of machine
>that work in "ttl" or maybe GALs. FPGAs want those funny sockets to hold
>all those pins and they are a bear to to probe a particular gate under a
>scope after delidding it. ;)
>
>Actually a discussion of PDP-4/7/9/15 would be of interest as those are
>thos ones I really do not know beyond trivial.
>
>Allison
>
Received on Mon Aug 30 1999 - 13:26:25 BST