Texas Instruments 990 Manual page 91

EXTCLOCK
NCEL
~
NCEL
CLK
TO REFRESH MEMORY,
PH1
LS51
~
VIDEO OUTPUT LOGIC
OSCILLATOR DOT RO
CEL
_J
1
CEL
DOTR1
DOTR2
--
LS04
CLOCK BUFFER/
b
SELECTOR
CEL ' -
~
A QA
~
• QB
,
QC
r--
r - -
B
QD
QE
CLK
CK
QF
,,-
FROM CRU
NRL2
QG
~CL
INTERFACE
...
LO~IC
QH
1--
LS164
~
DOT
I
COUNTER
3
DOTR4
DOTR5
(8)136298
DOTR1
DOTR3
DOTR4
DOTR5
DOTR6
LS04
NDOT4
-
-
LS04
NDOT5
~
368
~
NDOT6
a
_J
...,
TO REFRESH MEMORY, MEM ORY
C,
RACTER
>
READ/WRITE CONTROL LOG!
VIDEO OUTPUT LOGIC, CHA
SYNCHRONIZATION LOGIC
,,.
TO KEYBOARD LOGIC,
VIDEO OUTPUT LOGIC
TO CHARACTER
SYNCHRONIZATION LOGIC
1
--i
p
D2TRU5Q DOTR1
J
Q
CLK
LS109
CK
-
-
NDOT5
K
Q 1---
CL
NRL2
j
1-=;,_
p
D2TRU6Q
DOTRl
J
Q
CLK
LS109
CK
- -
NDOT6
K Q
~
NRL2
J
INTERVAL TIMERS
TO REFRESH
MEMORY,
MEMORY
READ/WRITE
CONTROL
LOGIC
TO REFRESH
MEMORY,
MEMORY
READ/WRITE
CONTROL
LOGIC, VIDEO
OUTPUT
LOGIC
Figure 1-49. Model 911
Vid~o
Display Controller Time Base
Generator Oscillator and Dot Clock
1-81/1-82
Digital Systems Division