WIRING
The wiring is quite straight forward and should present no major problems to
anyone. It follows my usual practice of NOT cutting any pcb tracks. The
instructions assume that the board is component side up and that the ‘BUS’ end
is nearest to you. Readers who decide to make this modification do so at their
own risk. I must disclaim any responsibility for any loss or damage. Having
said this, the modification really is very easy to do and I encourage you to try
it.
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First remove the permanent wire link on LK1, noting the original position
which in my case was A-B. This information will be used later to route
through the original 1MHz clock to the correct gate.
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With the aid of figure 2, locate and mark out the positions for the 14 pins
of the 74LS00 chip. You can use a small piece of 0.1″ vero board as a
template.
figure 2: suggested chip placement
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Double check that no tracks are underneath before dril1ing out the holes
with a 1mm drill. Depending on the exact position of the holes, some may
straddle the etched lettering on the underside of the board. The affected
lettering should be removed. Place a hot soldering iron on the letters for
5-10 seconds and then firmly push the foil off with the edge of the iron.
Alternatively, if you don’t want to drill holes in the pcb, you could splay
out the legs of the 74LS00 and secured it to the underside of the board
with glue or double sided tape.