TM 5-6675-323-14
(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
circuit initializes (clears) all the HP-IB Interface functions and circuits within
the HP-IB Interface and generates a 100 microsecond pulse on the IFC line.
(b) If the computer is the active controller, the control logic circuit
enables the computer interrupt logic circuit and sets the immediate control (IMD)
signal true.
(c) If the plotter then sends an abort message (IFC), the circuit also
initializes (resets) all the HP-IB Interface functions and circuits.
If, in addi-
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), E0I, and not-data-available (NDAC) lines
low.
(8) The parallel poll logic circuit allows the HP-IB Interface to respond to
a parallel poll by the plotter. The plotter initiates a poll by sending ATN and E0I
true signals.
If the computer has requested service from the plotter, a service
r e q u e s t ( S R Q ) s i g n a l i s r e c e i v e d f r o m t h e H P - I B c o n t r o l b u s l a t c h c i r c u i t . The SRQ
signal induces the parallel poll logic circuit to respond to the parallel poll by
sending a status signal to the plotter via one of the data lines (DI01 thru DI08).
3-3.2.2 (Internal) Interface Circuits. The interface circuits allow transfer in
and out of plotter of data and control information. The interface circuits consist
of the following two printed boards:
I n t e r c o n n e c t PCA Card A1
I n t e r n a l Interface Bus PCA Card A2
I n t e r c o n n e c t PCA card A1.
Houses the connectors for the input/output cable,
the ADDRESS switch S1 integrated module, CONFIDENCE TEST switch and LISTEN ONLY
switch.
( 1 ) The ADDRESS switch S1 integrated module provides an eight-bit address
c o d e to the address comparator in PCA A2.
T h e module is set according to the
operating instructions.
(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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