ACT apricot - CRTC Connections

CRT CONTROL
second write is to address location 6AH in the system
input/output space, which loads the value into the control
register, specified by the pointer.
Register
Text
Graphics
Register
Text Graphics
{Hex}
{Hex)
{Hex)
{Hex)
RO
5E
3B
R8 03
03
Rl
50
32 R9
DE DE
R2
4F
30
RIO 00
00
R3
DC
DC
Rll OF OF
R4 19
19
R12 00 00
R5
OA
OA
R13 00
00
R6 19 19
R14
00
00
R7
19
19
R15
00 00
CRTC Connections
DO to D7 Data bus. Used to transfer data between the
internal registers of the CR TC and the
processors.
R/W
Read/write control input connected to the
DT/R control line of the system control bus.
Used in conjunction with CS, RS and E to
control data transfers between the CRTC and
the processors. R/W determines the direction of
data transfer; logic high from the CRTC (read),
logic
low to the CRTC (write).
CS Chip Select. Address input. Active state, logic
low.
When active indicates that the CRTC is
selected for a
data transfer operation.
RS Register Select. Input connected to Al of the
system address bus. Used to select either the
address register (logic low) or one of the
eighteen control registers (logic high).
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