Texas Instruments 990 Maintenance Manual page 9

CRUBIT15
CRUBIT14
CRUBIT13
CRUBIT12
IMODSELA-
CRUDATAOUT
STORECLOCK-
(A)133015
----
-
-
l
,,
l
~
,
.
'
'
~·
~CRUDATAIN
-
CPU DATA CPU COMMAND
16 TO 1
--
ADDR DECODER ADDR DECODER
-
LINE
MULTIPLEXER
L.
jJ
CRU INT-
l
COMMAND AND
-
r=--
STATUS CONTROL
,,
,.
TRANSMIT
-
TRANSMIT
j~ ·~
-
RECEIVE
SHIFT TIM ING AND
~
BUFFER
GATING CONTROL
REµ I STER
.----
l
l
,,
BAUD RATE
RECEIVE
14--
GENERATOR
SHIFT
REGISTER
TRANSMIT
~
SHIFT
REGISTER
!
OSCLK
!
L - - -
4 MHZ
RECEIVE
CRYSTAL TIMING AND i----
OSCILLATOR DATACLK_
CONTROL
-
,.
_t~
t~
TTY LINE EIA LINE
-
EIA COMPATIBLE TERMINAL
-
INTERFACE INTERFACE
-
l
TTY COMPATIBLE TERMINAL
-
-
Figure 1-2. Full Duplex TIY /EIA Interface Module Simplified Block Diagram