saa5288 NXP Semiconductors, saa5288 Datasheet - Page 22

• Manufacturer Part Number: saa5288
• Description: Microcontroller With Full Screen Screen Display
• Manufacturer: NXP Semiconductors

Philips Semiconductors
7.5.4
In common with their predecessors, these devices store
teletext pages as a series of 8-bit character codes which
are interpreted as either control codes (to change colour,
invoke flashing etc.) or displayable characters. When the
control characters are excluded, this gives an addressable
set of 212 characters at any given time.
More characters than this were required to give the
language coverage required from the first version of the
device. The TXT4. East/West bit was introduced to allow
the meanings of character codes D0H to FFH to be
changed, depending on where in Europe the device was to
be used. This bit is still used with the other language
variants, although the name East/West may not make
much sense.
7.5.5
The interpretation of some character codes between 20H
and 7FH depends on the C12 to C14 language control bits
stored in row 25 of the display page.
The interpretation of the C12 to C14 language control bits
is dependant on the East/West bit.
7.6
In many of the character sets, the ‘twist’ serial attribute
(code 1BH) can be used to switch to an alternative basic
character code table, e.g. to change from the Hebrew
alphabet to the Arabic alphabet on an Arabic/Hebrew
device. For some national option languages the alternative
code table is the default, and a twist control character will
switch to the first code table.
The display hardware on the devices allows one language
to invoke the alternative code table by default when the
East/West register bit is a logic 0 and another when the bit
is a logic 1. In all of the character sets defined so far, the
language which invokes the alternative code table is the
same for either setting of the East/West bit.
7.6.1
In the character sets, character codes 80H to 9FH are
OSD symbols. An editor is available to allow these
characters to be redefined by the customer.
1997 Jun 24
TV microcontroller with full screen
On Screen Display (OSD)
The twist attribute
E
N
O
AST
ATIONAL OPTION CHARACTERS
N SCREEN DISPLAY SYMBOLS
/
WEST SELECTION
22
7.6.2
The devices have a readable register TXT12 which
contains a 5-bit identification code TXT12.ROM VER R4 to
TXT12.ROM VER R0 which is intended for use in
identifying which character set the device is using.
7.6.3
When used with 525-line display syncs, the devices modify
their displays such that the bottom line is omitted from
each character cell. The character sets have been
designed to be readable under these circumstances and
anyone designing OSD symbols is advised to consider this
mode of operation.
7.6.4
Character codes 00H to 1FH, B0H to B7H and
BCH to BFH are interpreted as control characters which
can be used to change the colour of the characters, the
background colour, the size of characters, and various
other features. All control characters are normally
displayed as spaces.
The alphanumerics colour control characters (00H to 07H)
are used to change colour of the characters displayed.
The graphics control characters (10H to 17H) change the
colour of the characters and switch the display into a mode
where the codes in columns 2, 3, 6 and 7 of the character
table (see the character table above) are displayed as the
block mosaic characters in columns 2a, 3a, 6a and 7a.
The display of mosaics is switched off using one of the
alphanumerics colour control characters.
The ‘new background’ character (1DH) the background
colour of the display sets the background colour equal to
the current foreground colour. The ‘black background’
character (1CH) changes the background colour to black
independently of the current foreground colour.
The background colour control characters in the upper half
of the code table (B0H to B7H) are additions to the normal
display control characters which allow the background
colour to be changed to any colour with a single control
character and independently of the foreground colour.
The background colour is changed from the position of the
background colour control character.
L
525-
C
ANGUAGE GROUP IDENTIFICATION
ONTROL CHARACTERS
LINE OPERATION
Preliminary specification
SAA5288