SAA5531 Philips Semiconductors, SAA5531 Datasheet - Page 63

• Manufacturer Part Number: SAA5531
• Description: Enhanced TV microcontrollers with On-Screen Display OSD
• Manufacturer: Philips Semiconductors

Philips Semiconductors
19.3.14 C
The cursor operates by reversing the background and
foreground colours in the character position pointed to by
the active cursor position. The cursor is enabled using
TXT7.CURSOR ON. When active, the row the cursor
appears on is defined by TXT9.R<4:0> and the column is
defined by TXT10.C<5:0>. The position of the cursor can
be fixed using TXT9.CURSOR FREEZE.
CC: The valid range for row is 0 to 15. The valid range for
column is 0 to 47. The cursor remains rectangular at all
times, it’s shape is not affected by italic attribute, therefore
it is not advised to use the cursor with italic characters.
TXT: The valid range for row positioning is 0 to 24.
The valid range for column is 0 to 39.
19.3.15 S
CC/TXT: Several special characters are provided for
improved OSD effects. These characters provide a choice
of 4 colours within a character cell. The total number of
special graphics characters is limited to 16.
2000 Feb 23
handbook, full pagewidth
handbook, full pagewidth
Enhanced TV microcontrollers with
On-Screen Display (OSD)
This example could also be done with 8 special characters.
PECIAL GRAPHICS CHARACTERS
URSOR
background colour
background colour
"set at" (Mode 0)
A B
foreground colour 7
Fig.29 Special character example.
VOLUME
Fig.28 Cursor display.
C
serial attribute
special character
foreground colour
normal character
63
They are stored in the character codes 8XH and 9XH of
the character table (32 ROM characters), or in the DRCs
which overlay character codes 8XH and 9XH. Each
special graphics character uses two consecutive normal
characters.
Fringing, underline and overline is not possible for special
graphics characters. Special graphics characters are
activated when TXT20.OSD PLANES = 1.
If the screen colour is transparent (implicit in mixed mode)
and inside the object the box attribute is set, then the
object is surrounded by video. If the box attribute is not set
the background colour inside the object will also be
displayed as transparent.
Table 20 Special character colour allocation
D E F
PLANE 1
0
0
1
1
"set after" (Mode 1)
background colour
foreground colour 6
PLANE 0
0
1
0
1
MGK550
MBK971
background colour
foreground colour
CLUT entry 6
CLUT entry 7
COLOUR ALLOCATION
Preliminary specification
SAA55xx