21 Feb
2017
21 Feb
'17
12:41 p.m.
tisdag 21 februari 2017 skrev Jecel Assumpcao Jr. <jecel at merlintec.com>:
Jim Brain wrote:
Right now I am in the situation of having a 16L8 with unknown program so I
have been thinking (and googling) to find a solution. I have come to the
conclusion that this device has to be considered as 262144 by 8 ROM. 18
bits address space because it has 8 three state outputs (six of them may
act as inputs) which has to be probed in what way they are active driving
or not and then 10 inputs. I was thinking of driving the outputs through a
1k or so resistor and then reading back the outputs.
The inputs are of course driven as usual. Then I need to write some small
piece of software to deduce the OE pin values and minimise the equations
using some program mentioned above in the thread.
I have seen someone making a small device to do this.
http://dreamjam.co.uk/emuviews/elec/pal.php
Unfortunately the software doesn't seem to be available any longer. Anyone
that has it? It would definetely save me some time.
/Mattis
As a function of "give a man a fish, you
feed him for a day; teach a man
to fish, you feed him for all time", I dloaded Logic Friday, and figured
out a quick way to read the two 16L8 (combinatorial only) PALs on the
board with my EPROM reader (cue duct tape and baling wire snickers).
Don't forget that 16L8 means 8 logic outputs and 16 inputs even though
at first glance there only seems to be 8 inputs. That is because every
output is also an input and can possibly be just an input by forcing the
three state option.