DEC VT220 - Page 104

300 H
2FF H
..... ---- ... 7FFH
BANK 3
CHARACTER
IA8=ll
IA9=1 A10=1j I
- - - - -1700 H
BANK 3 6FF H
ATTRIBUTE
(A8=Oi I
(A9=1, A10=1) ,
-----,600H
BANK 2 Ii 5FF H
'I' CHARACTER
(A8=1! "
IA9=0, A10=111
- _ _ - - 500H
BANK 2 4FF H
ATTRIBUTE
(AB=O)
IA9=0, A10=111
_____ 400 H
I BANK 1 , 3FF H
I
CHARACTER
(A8=11
,IA9=l, A10=01
BANK 1
ATTRIBUTE
n (AB=O)
I (A9=], A10=01
- - - - -1200 H
BANK 0 l1FF H
CHARACTER '
(AB=1)
IA9=0 A 10=0)
- - - - - 100 H
BANK 0 OFF H
ATTRiBUTE
t (AB=OI '
I(A9=O, A1O=O) I
! 1
000
H
Figure 6-15
Line Buffer RAM
Memory Map
FROM
B051 CPU .i.:..~;";";";"';;;'"
FROM
SCREE'N RAM4- --J
FROM {SYNC OM'" H
TIMING T5l
GEN ------+----.....,,-Clr- ........
FROM
ACCESS VIDEO LATCH H
MUX LBF DISABLE H
FROM
CPU LOGIC
FROM
ATTR IBUTE .L.;.;A..;;,D..;;,0_H;.,-_A;,;;D,;.7,;.H __ ...
RAM
CHAR
LATCH
1
TO
CHAR
OUTPUT
TO
LINE
BUFFER
TO
ATTRIBUTE
CIRCUITS
Figure 6-16
Data Input Buffers Block Diagram
6-20