SAA5281GP Philips Semiconductors, SAA5281GP Datasheet - Page 27

• Manufacturer Part Number: SAA5281GP
• Description: Integrated Video input processor and Teletext decoder IVT1.8
• Manufacturer: Philips Semiconductors

Philips Semiconductors
CHARACTER SETS
The WST specification allows the selection of national
character sets via the page header transmission bits,
C12 to C14. The basic 96 character sets differ only in
13 national option characters as indicated in the
Tables 21, 22 and 23 with reference to their table position
in the basic character matrix illustrated in Table 20.
The IVT1.8* automatically decodes transmission bits
C12 to C14. Tables 14, 15 and 16 illustrate the character
matrixes.
Character bytes are listed as transmitted from b1 to b7.
1996 Nov 04
handbook, full pagewidth
Integrated Video input processor and
Teletext decoder (IVT1.8*)
alphanumerics and
graphics character
graphics 'space'
contiguous
character
0000010
0110111
graphics character
alphanumerics
separated
character
1011010
0110111
Fig.14 Character format.
27
=
Meshing
This is an alternative method of displaying teletext
subtitles, or similar boxed text superimposed on the TV
picture and operates by showing reduced contrast TV
pictures in place of the (black) background within the
boxed area. The Meshing effect is produced by toggling
the BLAN signal from IVT at pixel rate. By starting at the
same point each field, and toggling the start position each
line, a chequered pattern will result. This allows movement
to be seen behind the text information. The MESH
OFF/ON bit in Register 13 D5 controls this function.
Normally at zero, compatibility with IVT1.0 is maintained.
background
graphics character
alphanumerics or
alphanumerics
blast-through
colour
character
separated
0001001
1111111
=
display
colour
graphics character
alphanumerics
contiguous
character
1111111
1111111
MLA663
Preliminary specification
SAA5281