Vector Graphic Bitstreamer II, User Manual, Page: 39 / 54

Serial Channel C can be used for 20 mAcurrent loo~ COffinlW1icationra~1er
than RS-232C. To convert it, install a jumper connecting pad 1 and pad 2 in
area G, found about 2 inches from the upper right-hand corner of ~1e board.
The current loop inputs and outputs are then connected to four of the six
pins of the molex coru1ector J6, in the upper right-hand corner of the board.
Use only the first four pins from left to right. They have the following
functions from left to right:
+
IN, - IN,
+
OUT, - OUT.
Before using this section, read over Sections 1.5, 1.9, and 1.10 in
Perspective.
The three 8251 TxRDYpins, the three 8251 RxRDYpins, and ~he 55 Hz real
time clock are accessed in jumper area A, as listed below: (Mask bit will be
explained later.)
Interrupt Source Pad in Area A Mask Bit
Serial
ChanneI A TxRDY 3
0
Serial Channel A RxRDY
6
1
Serial Channe 1 B T".<RDY
7 2
Serial Channel B RxRDY
4 3
Serial Channe
1
C TxRDY
2 4
Serial Channel C RxRDY
5 5
55 Hz
Real Time Clock
1
6
PINT
8
To cause one of the TxRDY, RxRDY,or real time clock lines to interrupt
the processor, install a jumper bet:..,.een the appropr ia te pad in a raa A and
pad 8 in area A. Pad 8 runs directly to the PI~T line of G~e
5-100 DjS.
To
cause mre wan one TxRDY and/or RxRDY line to interrupt the processor,
simply tie all desired pads toge~1er in area A and then tie them to pad 8.
(For readers r.i1o understand digital electronics, this can be done because
the
8251
interrupt sources are connected to area A via open collector
gates. )
However, you C~~NOT tie the real time clock to pad
A-a
in combination
wi th the 8251 interrupt sources. If you want to use the real time clock as