TM 5-6675-323-14
b. The functions are accomplished by the following functional units:
Signal
lines
Select code decoder circuit
I/O register decoder circuit
Computer command register circuit
I/O data register circuit
Computer
interrupt
logic
circuit
Control
logic
circuit
Interrupt
logic
circuit
HP-IB transceiver circuit
HP-IB output data latch circuit
HP-IB address register circuit
HP-IB input multiplexer circuit
HP-IB control bus latch circuit
Parallel
poll
logic
circuit
(1) Signal lines carry the data, information, and control signals between
t h e HP-IB Interface ROM, the computer and the plotter (Tables 3-1 and 3-2). Signal
lines can be grouped by function into four groups:
Data lines
Transfer lines
Control
lines
I/O lines
(2) Data lines are found on both sides of the HP-IB Interface. They contain
all the signals that communicate data, including input, output and program codes;
address control; and status information. Transfer lines hold the signals that
control the transfer of each byte of information between the plotter (via HP-IB) and
Signals on the control lines are primary
the HP-IB Interface (either to or from).
control signals and govern the flow of information over both the transfer and data
Signals on the I/O lines perform
lines between the HP-IB Interface and the plotter.
t h e same functions between the HP-IB Interface and computer, as those on the
transfer and control lines do between the HP-IB Interface and the plotter.
3-7
