How not to fix a classic mac (or: fried logic boards)

[Grant Stockly]

At 03:17 PM 11/14/2007, you wrote:
> > The LAG is labeled "HAL16R8CN 8440 / 342-0251-A" so it does look like a
> > custom ("HAL") chip such as what Tony was mentioning.  Guess that would
>
>It is. The important part of the number is the '16R8' bit. That implies
>it's got 8 registered ouptuts and a total of 16 inputs to the AND array
>(8 serpate inputs and 8 feedback terms from the output pins). That, of
>course, accounts for 16 pins on the 20 pin package, the others are +5V,
>ground, a common clock input to all the flip-flops, and a common output
>enable signal to all the outputs).
>
>It's the same architecture as a PAL16R8, and could be replaced by a
>suitably-programemd GAL16V8. Not that that is any help at all without the
>PAL equations.
>
>I will try to find all my notes on the Mac+ (but not tonight!). I know I
>never figured out the PAL equations, but I might have something of use.

There are equations for the PALs on my website:
http://www.stockly.com/forums/showthread.php?t=6