Specifications

I/O Simulation Pseudo–Devices 119
SPST Switch
The SPST switch device simulates the actions of a simple open/closed
switch in a digital circuit. When a switch is first created, it is open, and
both connections present a high impedance logic level. Clicking on the
switch (between the two dots) with the cursor in Point mode causes the
switch arm to close and the switch to “conduct.” In terms of the digital sim-
ulation, this means that whatever logic level is present on each pin is trans-
mitted to the other one.
An SPST switch has a default delay of zero but this can be set to any value
from 0 to 32,767 using the Simulation Params command.
SPDT Switch
The SPDT switch device operates in essentially the same manner as the
SPST switch described above, except that it always conducts between the
single pin on one side and one of the two pins on the other. As with the
other two switch types, clicking on it with the arrow cursor changes the
position of the contact.
SPDT Pushbutton
The Windows SPDT Pushbutton switch device operates in essentially the
same manner as the SPDT switch described above, except that it only stays
switched to one side while the mouse is pressed.
Binary Probe
The Binary Probe is a device for displaying the level present on any signal
line. When the probe is first created, its input is unconnected and therefore
in the High Impedance state, which will be displayed as a “Z”. When the
input pin is connected to another signal, the displayed character will
change to reflect the new signal’s current state. Any further changes in the
signal state will be shown on the probe. Possible displayed values are 0
(low), 1 (high) X (Don’t Know), Z (High Impedance), or C (Conflict).
LW Reference.bk Page 119 Monday, December 15, 2003 5:59 PM