Hi everyone,

Some quick pointers that the labs writeups didn't cover too well:

1) What does X and Z mean in the simulator???

Z means disconnected.

X means the simulator doesn't know.

If you get a Z, check your wiring connections. If you get an X, you
might have
mislabeled wires, or you might have done something that confused the
simulator
(like trying to use a stimulator on the output of a gate...).

2) What's up with this "Select Stimulator" dialogue box.

Prof. Katz explained the B0, B1, ... choices in the stimulators box,
but you're
probably wondering what the QWERTY keyboard and that 0 and 1 does.

The QWERTY keyboard allows you to assign an input to the key Q. Now
whenever you press Q, the value of that wire will toggle between 0
and 1.

The 0 and 1 allows you to assign a wire to be always 0 or always 1.

3) What are these complex buses Lab 2 mentions?

For those of you running ahead to Lab 2, complex buses can be used
to collect
multiple buses and individual wires into a single bus.

Let's say we need a 16-bit bus, with the highest order bit a to be
connected to 5v,
(aka VCC), the next bit to ground (aka GND), then we need to splice
in an 8-bit
bus called Foo[7:0], then another bus called Bar[6:2], then another
VCC. First, we
draw a bus. Assume we've got a VCC symbol with a wire called VCC
attached to it
in the schematic. Then, when we need to name the bus with a label or
a terminal, we
need to:
a. uncheck the "simple bus" option
b. In the text entry box now titled "complex bus label" we need
to type
VCC, GND, Foo[7:0], Bar[6:2], VCC

4) What does "clock clk 0 1" mean?

This simulator command will make the wire called clk act like a
clock. Yay. The 0 1
just means that for the first step period clk will be 0, then the
next 1, then repeat.

If you said "clock clk 0 0 1" then clk would be 0 for a period, 0
for a period, 1 for a
period, then repeat.

--Laura