TM 5-6675-320-14
(a) When the plotter is the active controller and wishes to abort or
clear the HP-IB Interface, it sends an IFC signal. The computer interrupt logic
c i r c u i t i n i t i a l i z e s ( c l e a r s ) a l l t h e H P - I B I n t e r f a c e f u n c t i o n s a n d c i r c u i t s w i t h in
the HP-IB Interface and generates a 100 microsecond pulse on the IFC line.
( b ) I f t h e c o m p u t e r i s t h e a c t i v e c o n t r o l l e r , t h e c o n t r o l l o g i c c i r c u it
enables the computer interrupt logic circuit and sets the immediate control (IMD)
s i g n a l t r u e .
(c) If the plotter then sends an abort message (IFC), the circuit also
i n i t i a l i z e s ( r e s e t s ) a l l t h e H P - I B I n t e r f a c e f u n c t i o n s a n d c i r c u i t s . I f , i n a d d i-
tion, the plotter sends an attention (ATN) true signal, indicating an expected
transmission of data or information, the circuit readies the HP-IB Interface to
receive data.
Readiness is established by clearing HP-IB output data latch circuit,
disabling HP-IB transceiver circuit transceivers and sending signals on the data-
available (DAV), not-ready-for-data (NRFD), EOI, and not-data-available (NDAC) line s
low.
( 8 ) T h e p a r a l l e l p o l l l o g i c c i r c u i t a l l o w s t h e H P - I B I n t e r f a c e t o r e s p o n d to
a p a r a l l e l p o l l b y t h e p l o t t e r.
The plotter initiates a poll by sending ATN and EOI
t r u e s i g n a l s.
If the computer has requested service from the plotter, a service
request (SRQ) signal is received from the HP-IB control bus latch circuit.
The SRQ
s i g n a l i n d u c e s t h e p a r a l l e l p o l l l o g i c c i r c u i t t o r e s p o n d t o t h e p a r a l l e l p o l l by
sending a status signal to the plotter via one of the data lines (DIO1 thru DIO8).
4 - 3 . 2 . 2
( I n t e r n a l ) I n t e r f a c e C i r c u i t s .
T h e i n t e r f a c e c i r c u i t s a l l o w t r a n s f e r in
and out of plotter of data and control information.
T h e i n t e r f a c e c i r c u i t s c o n s i s t
of the following two printed boards:
Interconnect PCA Card A1
Internal Interface Bus PCA Card A2
a. Interconnect PCA card A1.
Houses the connectors for the input/output cable,
the ADDRESS switch S1 integrated module, CONFIDENCE TEST switch and LISTEN ONLY
s w i t c h .
(1) The ADDRESS switch S1 integrated module provides an eight-bit address
code to the address comparator in PCA A2.
The module is set according to the
o p e r a t i n g i n s t r u c t i o n s .
(2) All communications in and out of the plotter are done via the eight
data lines and eight control lines that transverse PCA1.
(3) The CONFIDENCE TEST switch selects the plotter self-test.
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