Table of Contents
Advertisement
When jumpered, the bottom pair of pins on P8, labeled G, connects a I kilohm pull-down resistor to the output
of a high-impedance tri-state driver which carries the intemrpt request signal. This pull-down resistor drives tle
intemrpt request line low whenever intemrpts are not active. Whenever an intemrpt request is made, the tri-state
buffer is enabled, forcing the output high and generating an intemrpL You can monitor the interupt strtus through
bit 2 in the status word (I/O address location BA + 0). After the intemrpt has been serviced, the reset command
returns the IRQ line low, disabling the tri-state buffer, and pulling the ouput low again. Figure l-9 shows this
circuit. Because the intemrpt request line is driven low only by the pull-down resistor, you can have two or more
boards which share the same IRQ channel. You can tell which board issued the intemlpt request by monitoring each
board's IRQ status bit.
NOTE: When you use multiple boards that share the same interrupt, only one board should have the G jumper
installed. The rest should be disconnected. Whenever you operate a single board, the G jumper should be installed-
I N T
S O U R G E
I R O S T A T U S
I N T E R R U P T
g"
Fig. 1-9 - Pulling Down the Interrupt Request Line
P9 - DAC 1 Output Voltage Range (Factory Setting: +5 to -5 volts)
This header connector, shown in Figure l-10, sets the output voltage range for DAC 1 at 0 to +5, +5, 0 to +10,
or +10 volts. Two jumpers must be installed, one to select the range and one to select the multiplier. The two
rightmost jumpers select the range, bipolar (15) or unipolar (5). The twoleftmost jumpers select the multiplier, X2
or Xl. When a jumper is on the X2 multiplier pins, the range values become +10 and 10. The table below shows the
four possible combinations of jumper settings, and the diagram shows the factory setting. This header does not have
to be set the same as Pl0.
Voltage Range
Jumpers (Left to Blght)
x2
x1
r5
5
-5 to +5 volts
OFF
ON
ON
OFF
0 to +5 volts
OFF
ON
OFF
ON
-1 0 to +10 volts
ON
OFF
ON
OFF
0 to +10 volts
ON
OFF
OFF
ON
t-7
Advertisement
Table of Contents
