Tandy 1000
Advance
InforDl.ation
CRT CONTROLLER (CRTC)
The MC6845 CRT Controller performs
the
interface
to
raster scan
CRT displays. It
is
intended
for use
in
processor-based controllers for
CRT terminals
in
stand-alone
or
cluster configurations.
The CRTC
is
optimized for hardware/software balance
in
order
to
achieve integration of
a"
key functions and maintain flexibility.
For
instance, all keyboard functions, R/W. cursor movements. and editing
are under processor control; whereas
the
CRTC provides video timing
and Refresh Memory Addressing.
• Applications include "glass-teletype." smart. programmable. intel-
ligent CRT terminals; video games; information display.
• Alphanumeric, semiijraphic. and full graphic capability.
•
Fully
programmable
via
processor
data
bus. Can generate timing
for
almost
any alphanumeric screen density, e.g.
80
x
24,
72
x 64,
132
x 20. etc.
• Single
+5 volt supply.
TTL/6800
compatible
I/O.
• Hardware scroll (paging
or
by
line
or
by character!
•
Compatible
with CPU's and MPU's which provide a means for
synchronizing external devices.
• Cursor register and compare circuitry.
• Cursor
format
and blink are programmable.
• Light pen register.
• Line buffer-less operation. No external DMA required. Refresh
Memory
is
multiplexed between CRTC and
MPU.
• Programmable interlace
or
non·interlace scan.
• 14-bit wide refresh address.
Technical Reference Manual
MC6845
MOS
(N-Channel, Silicon-Gate)
CRT CONTROLLER
(CRTC)
~
CERAMIC
PACKAGE
CASE
715
NOT
SHOWN;
P
SUFFIX
PLAST
Ie
PACKAGE
CASE
711
FIGURE
1 -
TYPICAL
CRT
CONTROLLER
APPLICATION
H
Sync
V
Sync
This
i.
advance
information
and
specification
••
r.
IUblect
to
cheng.
without
notic
•.
CMOTOROlA
INC., 1917
AD1-465
(Replaces
NP-67)
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