TM 5-6675-318-14
(a) The operation of the HP-IB Interface ROM circuitry is dependent on
the requirements of the computer or plotter as indicated by the status of signals on
Direction of signal flow depends on which system (computer, HP-IB
the signal lines.
Interface, or plotter) is the active controller and, during an interchange, which
device is talking (the active controller or the HP-IB Interface) and which is
listening.
Signal Direction
(CMPTR
INTFC)
Function
Description
Line*
DATA LINES
Carries all data.
Input/Output Data
Identifies peripheral
Peripheral
Address
device to be addressed.
I/O LINES
L a t c h e s inputs and out-
R e g i s t e r Code
puts into register.
Determines transfer
Direction of Transfer
direction.
(1 = Out)
Initiates transfer.
I / O Strobe
Indicates HP-IB Inter-
Interface Flag
f a c e readiness to com-
(1 = Ready)
puter.
Indicates HP-IB Inter-
Interface Status
face presence to computer.
( 1 = Present)
Resets
HP-IB
Interface.
Calculator
Initialize
Low
priority
request.
I n t e r r u p t Request Low
(-7)
High priority request.
I n t e r r u p t Request High
(8-15)
D e m a n d s response to poll.
Interrupt Poll
* Bar over line designation stands for negative-true logic.
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