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PDF UM6845A Data sheet ( Hoja de datos )

Número de pieza UM6845A
Descripción CRT Controller
Fabricantes UMC 
Logotipo UMC Logotipo



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No Preview Available ! UM6845A Hoja de datos, Descripción, Manual

(l)UMC
UM6845/UM6845A/UM6845B
CRT Controller
Features
• Applications include smart, programmable, intelligent
CRT terminals; video games; information display
• Alphanumeric, semi-graphic, and full graphic capa-
bility
• Fully programmable via processor data bus and can
generate timing ·for almost any alphanumeric screen
density
• Single +5 volt supply, TTL compatibl-e I/O, NMOS
Technology
• Hardware scrolling by page, line or character
• Provides CPU's with synchronous signals to external
device
• Programmabfe cursor format
• Light pen registers and input strobe signal to latch the
light pen position on screen
• Line buffer-less operation. No external DMA required.
Reading screen memory is mutliplexed between CRTC
and CPU
• Programmable interlace or non- interlace scan
• 14-bit wide display memory reading address
General Description
The CRTC UM6845 family are LSI controllers designed
to provide an interface for microcomputers to raster
scan type CRT displays. The CRTC belongs to the
MC 6800 LSI Family and has full compatibility with
CPU in both data lines and control lines. Its primary
function is to generate timing signals which are necessary
for raster-scan type CRT displays according to the speci-
fication programmed by the .cPU.
Pin Configuration
VSS
RES
lPSTB
MAO
MAl
MA2
MA3
MA4
MA5
MA6
MA7
MA8
MAg
MAlO
MAll
MA12
MA13
DISPTMG
CUDISP
VCC
VSYNC
HSYNC
RAO
RAl
RA2
RA3
RA4
DO
Dl
D2
D3
D4
D5
D6
D7
CS
RS
E
R/W
ClK
5-3

1 page




UM6845A pdf
E
CS
Riw, RS
UM6845 / UM6845A / UM68458
f+---------tcyc E
2.0V
O.8V
1 4 - - - - tACC ---~
Figure 3. Read Sequence
E
CS
p/W
RS (Address Register)
RS (Control
Register)
DO-1?>7
1 4 - - - - - - - - tcYC E
PWEH
Figure 4. Write Sequence
CRTC SIGNAL TIMING
Item
Clock Cycle Time
Clock "High" Pulse Width
Clock "Low" Pulse Width
Rise and Fall Time for Clock Input
Memory Address Delay Time
Raster Address Delay Time
DiSPTMG Delay Time
CUDISP Delay Time
Horizontal Sync Delay Time
Vertical Sync Delay Time
Light Pen Strobe Pulse Width
Light Pen Strobe
Uncertain Time of Acceptance
* See Fig. 5; Fig. 6
Symbol
tcycC
PWCH
PWCL
tCr, tCf
tMAD
tRAD
tDTD
tCDD
tHSD
tVSD
PWLPH
tLPD1
tLPD2
Min.
270
130
130
-
-
-
-
-
-
-
60
-
-
5-7
2.0V
O.8V
Typ.
-
-
-
-
-
-
-
-
-
-
-
-
-
Max.
-
-
-
20
160
160
250
250
200
250
-
70
0
IUnit
nS
nS
nS
nS
nS
nS
nS
nS
nS
nS
nS
nS
nS

5 Page





UM6845A arduino
Example of Raster Scan Display
Fig. 13 shows an example where the same character is
displayed in the non-interlace mode, interlace sync mode,
UM6845 / UM6845A / UM68458
and video mode.
SCAN LINE ADDRESS.
SCAN LINE ADDRESS
0--o---
--
--------0
0
-9------G--1
20
0
-e------G--2
30
0
--9- -- - --€>- 3
4 00000
- 0- -6 -£)-0- G - 4
50
0
--6-----G-- 5
60
--9- -
-- -
-0e- 6
7 -e0 -- -
-
0
-G--- 7
- -e - - - - -£)- 1
o2
-
0
0-
-
-
-
4 000
0
--€)-3
}
00
LINE :fro
-0-------6-5
60
0
-<3------e-7
~====~~~=: }UNE #1
--------7
EVEN
FIELD
ODD EVEN
FIELD FIELD
ODD
FIELD
(al NON-INTERLACE
(bl INTERLACE SYNC
(Cl INTERLACE SYNC AND VIDEO
Figure 13. Interlace Control
Interface to Display Control Unit
MA
RA
CRTC
CLK
t
>14 max
~5max
v
DISPTMG
CUDISP
HSYNC
VSYNC
DISPLAY
MEMORY
~}
CHARACTER
GENERATOR
D
VIDEO
CONTROL
I
VIDEO SIGNALS
SYNC SINGNALS
0
0
0
Figure 14. Interface to Display Control Unit
Fig. 14 shows the interface between the CRTC and display
control unit. Display control unit is mainly composed
of display Memory, Character Generator, and Video
Control circuit. For display memory, 14 Memory Address
lines (0 -16383) max are provided and for character gen-
erator, 5 Raster Address lines (0-31) max are provided.
For video control circuit, DISPTMG signal is used to
control the blank period of video signal. CUDISP signal
is used as video Signal to display the cursor on the CRT
screen. Moreover, HSYNC and VSYNC signals are used
as drive signals respectively for CRT horizontal and vertical
deflection circuits.
Outputs from video control circuit, (video signals and sync
signals) are provided to CRT display unit to control the
deflection and brightness of CRT, thus characters are
displayed on the screen.
5-13

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