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Section IV -
P
rin ciples o f
O
perat ion
M odel 59313Α
4-22 .
ADDRESS ING OPERATION . Addressin g, whi ch ca n only be done in
t
he ΑΤΝ mode, is done as follows :
pulse .
(1)
Α code pl aced on the DATA IN lin es by the b us controller ca uses ge nerat ion
o
f an ΑΤΝ CLK
(2)
If th e code
i
s the LI STEN
A
DDRE SS code se lected by the jumpers, then th e L LSN line will be
l
atched LO.
(3)
If
t
he code
i
s the TALK ADDRE SS code se lected by t h e jumpers, then
t
he L ΤLΚ
l
ine will be
latc h ed
L
O.
4-23 .
UNTALK -UNLISTEN OPERATION. The L LSN line can be c l ea r ed (set HI) by :
(1)
IFR (INTERFAC E RE SET) pulse fro m RE SET CONTROL.
(2)
Receiving the U NLISTEN code .
Receiving the jumper se lected TALK A DDRE SS .
Th e L TLK lin e can be c lea r ed (set HI) by :
(1)
IFR (INTERFA C E RE SET) pulse fr om RE SET CONTROL.
(2)
Receiving the UNTALK code .
Receivi ng the jumper se lected LI STEN ADDRE SS .
(4)
Receivi ng any
T
ALK ADDRE SS other than the jumper-selected on e.
T
ALK and LISTEN ca nnot occur together.
W
hen L ΤLΚ is
L
O, ΑΤΝ
i
s non-assertive an d SERIAL POLL is
n
ot in
effect, then the 59313 Α
i
s in the TALK mode.
W
hen L LSN is
L
O and ΑΤΝ
i
s non-assertive, then the 59313Α is
in the LI STEN m ode .
4-24 .
Source
H
andshake Ci rcuit .
4-25 .
This ci r c ui t operates only in
t
he TLK mode (w ith or without the SERIAL PO LL m ode).
F
or t h e
handshake to take pl ace two co nditions are necessary :
(1)
Th e 59313 Α OUTPUT
S
EQUENCER sect ion mu st
h
ave pl aced its outpu t data on the 8 DI O
l
ines
and set the Η OUTPUT RE ADY line HI .
(2)
Th e b us listener(s) mu st
h
ave set the NRFD line HI and NDA C line
L
O. Two to
f
o ur microseco nd s
later the DAV (data valid) line will go
L
O to
i
nd icate to the listener(s) that the data is ready and at the sa me t im e
ΤLΚ CLK goes HI . When
t
he li stener(s)
h
ave acce p ted the data they set the NRFD line
L
O and the ND AC line
III
an d the so urce
h
andshake circui t then sets the DAV line HI an d th e TLK CLK line
L
0. (The Τ LΚ CLK
s
ignal is
used by the outpu t sequencer to get the next data byte ready .) Th e so urce
h
andshake
i
s d i sabled w h en either the
Η ΑΤΝ or L TLK line goes III.
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