Need Docs for XT RAM Board...

[Ethan Dicks]

On 11/17/06, Tony Duell <ard at p850ug1.demon.co.uk> wrote:
> > On 16 Nov 2006 at 14:34, Chris M wrote:
> > >  Possibly both. What if both were important?
> > Then you wouldn't be trying to separate them, would you? :)
>
> You might, if you needed to remove the chip for testing (either to test
> the chip, or to be able to force signals that it drove on the board so as
> to test other bits of the machine). Or if you wanted to read out the
> program from said chip (maybe it's a PAL or a microcontroller, or something).

Or have a use for the chip, but value the board as well (especially in
the case of being able to restore it to full functionality later).

> Yes, you can separate ICs and PCBs without damaging either. I do it all
> the time.

Me, too.  The most recent example I can think of is removing an
INS6120 12-bit CPU from a DECmate III board and sticking the chip into
an SBC6120.  I needed the chip right away, but I wanted to replace the
soldered 40-pin DIP CPU with a machined-pin socket for the day when I
wanted/needed to run that board in a DECmate chassis.

The entire board cost me $50, what a bare CPU would have cost, but I
wanted to retain two working parts, not just one.  For those keeping
score at home, the board is a 4-layer board with internal power/gnd
pins that do _not_ want to let go of a DIP CPU.  38 pins were easy...
the power and ground pins were not.  In the end, I managed to end up
with an intact CPU *and* an intact board, but unless you have
pro-grade tools, you'll find it difficult to replicate this effort.

-ethan