Texas Instruments 990 - Buffer Register; LED Display

-
I
w
Vi
---
-
I
w
°'
TO CRT
MONITOR
FROM
KEYBOARD
TO
SPEAKER
(B)l 36271 A
BIT
PIN
1 1
2
2
3
3
4
4
5
5
6
6
7
7
8
8
TP7
VERT,SYNC
TP6
J
3
_
6
~...:~...:10:..;.R_-...:s...:Y_N...:.c _____ ---49--e---1
J
3
_
4
( VIDOUT
)
Jt-9
J5-10
PARALLEL KEYBOARD DATA
KBDT, 1-B
TP9
KBSIN-
Ut2-B
TP10
REPEAT-
J5-1 ,2,4,5, ~(-A_u_D_1_0 ___________ ~
INVERTING
AMPLIFIER
AND DELAY
AUXILIARY
H-SYNC
GENERATOR
DUAL-GAIN
VIDEO
AMPLIFIER
BUFFER
REGISTER
REPEAT
LOGIC
AUDIO
AMPLIFIER
+5VDC
DIFFERENCE
AMPLIFIER
R12
TP4
COMPOSITE VIDEO CVID
RETR IGGERABLE
ONE SHOT
(NOT USED)
11-BIT SERIAL DATA
TBRLD-
000 000000 0 '
LED DISPLAY
AUDIO
OSCILLATOR
6
FROM VDT
CONTROLLER
TRD1T }
T
TO VDT
CONTROLLER
TET2T
TETIT
}
TO VDT
CONTROLLER
JZ-9
'----<"-.1-_:_:_:_:_ 'T_:-<:~'r ~~~!tR~E~ER
L-----------------------0 0 MODIN <
Figure 1-21. Model 911 VDT Power/Logic PWB Detailed Block Diagram
of Keyboard Data Path, Video, and Audio Logic
DISCRETE JUMPER
REQUIRED