mattislind at gmail.com
Tue Feb 21 14:41:27 CST 2017
tisdag 21 februari 2017 skrev Jecel Assumpcao Jr. <jecel at merlintec.com>:
> Jim Brain wrote:
> > 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.
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.
Unfortunately the software doesn't seem to be available any longer. Anyone
that has it? It would definetely save me some time.
More information about the cctalk