p87c770aar NXP Semiconductors, p87c770aar Datasheet - Page 60

• Manufacturer Part Number: p87c770aar
• Description: Microcontrollers Ntsc With On-screen Display Closed Caption
• Manufacturer: NXP Semiconductors

Philips Semiconductors
18.10 Character font format
The character font is a 12 (horizontal) x 13 (vertical)
matrix. The ROM contents have two extra lines in each
field to facilitate the fringing function when groups of
characters are used to build symbols.
A table with 128 characters, two columns of special
characters (32) and a column for proportional spaced
characters (16) is shown in Fig.27.
The ROM size is 176 characters x 12
(4224 bytes, 2816 x 12-bit words).
18.10.1 C
The character addressing scheme is dependent on what
type of character is accessed. Therefore, the ROM format
for the different columns changes respectively.
The ROM format is 16 locations in words of 12 bits, where
the MSB (bit 11) of the ROM word is the left most pixel of
a character displayed.
The lines 0 and 14 are used for fringing of clustered
characters (single images using more than one character)
over row boundaries. Lines 1 to 13 contain the font of the
character and line 15 is not used.
1999 Jun 11
handbook, halfpage
Microcontrollers for NTSC TVs with On-Screen
Display (OSD) and Closed Caption (CC)
number
Fig.23 Character ROM format columns 0 to 7.
line
10
11
12
13
14
15
0
1
2
3
4
5
6
7
8
9
HARACTER
HEX
00C
0C0
C00
C00
0C0
00C
440
003
030
300
300
030
003
000
198
000
top left
MSB
pixel
ROM
character below
line 0 from
character above
line 13 from
FORMAT
bottom right
16 = 33792 bits
pixel
LSB
bottom line
fringing
line not used
fringing
top line
MGL153
60
The proportional spaced characters use only bits 11 to 6
for display. Bits 5 to 0 are defined by repeating the
information held in bits 11 to 6 shifted up one line.
The ROM definition for these characters is shown in
Fig.24. Proportional characters can be displayed in
column A only.
The ROM format for the special characters uses two
subsequent character ROM locations. The character
definition will always start with an even character.
This location holds the information for bit Plane 0 the next
location (odd) contains the bit Plane 1. No shadowing is
supported when using these characters. The bit
combinations of Plane 0 and Plane 1 define which colour
is displayed for a certain pixel. A detailed description on
how these characters are displayed is found in
Section 18.2.16.
The ROM format for each plane is defined as stated for the
normal characters, except that the data on the fringing
lines is ignored.
handbook, halfpage
(1) Line 13 from character above.
(2) Line repeated from line 14 (bits 11 to 6).
(3) Line 1 from character below.
Fig.24 Proportional character ROM format
number
line
10
11
12
13
14
15
0
1
2
3
4
5
6
7
8
9
column A.
value
HEX
00C
00C
30C
30C
30C
30C
30C
000
000
300
306
180
000
000
000
000
11 (MSB)
fringe
fringe
not used
(1)
(3)
6
P8xCx70 family
5
fringe
not used
Product specification
(2)
0 (LSB)
MGL154