TM 5-6675-320-14
(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
t h e s i g n a l l i n e s .
Direction of signal flow depends on which system (computer, HP-IB
I n t e r f a c e , o r p l o t t e r ) i s t h e a c t i v e c o n t r o l l e r a n d , d u r i n g a n i n t e r c h a n g e , w h i ch
device is talking (the active controller or the HP-IB Interface) and which is
l i s t e n i n g .
Table 4-1. SIGNAL LINES BETWEEN COMPUTER AND INTERFACE
S i g n a l D i r e c t i on
L i n e*
D e s c r i p t i on
Function
(CMPTR
INTFC)
IODØ
IOD7
PAØ
PAØ
IC1 thru IC2
DOUT
IOSB
FLG
STS
INIT
IRL
IRH
INT
Input/Output Data
Peripheral Address
DATA LINES
C a r r i e s a l l d a t a .
I d e n t i f i e s p e r i p h e r al
device to be addressed.
I/0 LINES
Register Code
D i r e c t i o n o f T r a n s f er
(1 = out)
1/0 Strobe
I n t e r f a c e F l ag
(1 = Ready)
I n t e r f a c e S t a t us
(1 = Present)
C a l c u l a t o r I n i t i a l i z e
Interrupt Request Low
(Ø-7)
Interrupt Request High
( 8 - 1 5)
I n t e r r u p t P o ll
Latches inputs and out-
p u t s i n t o r e g i s t e r.
Determines transfer
d i r e c t i o n .
I n i t i a t e s t r a n s f e r .
Indicates HP-IB Inter-
face readiness to com-
p u t e r.
Indicates HP-IB Inter-
face presence to computer.
Resets HP-IB Interface.
Low priority request .
H i g h p r i o r i t y r e q u e s t .
Demands response to poll.
* Bar over line designation stands for negative-true logic.
4-8
