1. LOG nodes which are not connected to any transistors or cells
are ignored. Thus, you can not get orphan nodes just by drawing
stray wires. You must explicitly use "orphan" gates as described
above under ORPHAN.
2. Cells which pass "global" nodes to their subcells, but which do
not actually use those nodes themselves, must include those
global names in their own port lists. For example, if a
higher-level cell does not use GND and VDD but its subcells do,
you must include GND and VDD in this cell's PORT list. (Note
that if you are using the recommended "template gate" method
rather than writing a PORT list, this is all handled for you
3. LOGNTK is case-insensitive, but case-preserving. That is, if you
call something FOO in some places, and Foo in others, the names
will be considered the same, and one of the names will be chosen
for use everywhere in the output file. Which name is chosen is
arbitrary, except that preference is given to usage in the PORT
command. Note that LOG itself is case-sensitive in some ways,
for example, TO/FROM signal names "Vdd" and "VDD" are considered
to be different by LOG but this difference is not acknowledged by
LOGNTK. This sort of disagreement can cause LOGNTK to produce
strange or erroneous output files.
4. The "VDD" and "GND" symbols are exactly equivalent to TO's or
FROM's with the names Vdd and Gnd, respectively.
5. In LOGED, you can use the CONNECT command to cause two pins to be
connected internally. (For example, the crossing-wires gate
CROSS2 and the toggle switch SW2 work this way.) If you use such
a gate as an instance in LOGNTK, only the lowest-numbered of the
connected pins corresponds to a port in the PORT list; the other
pins in the connection group are skipped when being matched to
ports, in the same way as global ports are skipped when being
matched to pins. Once again, using a template gate to describe
your ports handles this automatically.
6. GINST gate symbols include an arrow -- this arrow signifies the
pin which is numbered "pin 1". Pins are numbered consecutively
from this pin, moving in a clockwise direction.
- john [dot] lazzaro [at] gmail [dot] com