saa5244a NXP Semiconductors, saa5244a Datasheet - Page 17

• Manufacturer Part Number: saa5244a
• Description: Integrated Teletext Decoder Ivt1.1
• Manufacturer: NXP Semiconductors

Philips Semiconductors
SAA5244A page memory organization
The organization of the page memory is shown in Fig.9. The device provides an additional row as compared with first
generation decoders; this brings the display format up to 40 characters by 25 rows. Rows 0 to 23 form the teletext page;
row 24 is available for software generated status messages and FLOF/FASTEXT prompt information.
March 1992
Row 0:
Row 0 is for the page header. The first seven columns (0
to 6) are free for status messages. The eighth is an
alphanumeric white or green control character, written
automatically by SAA5244A to give a green rolling header
when a page is being looked for. The last eight characters
are for rolling time.
Row 25:
The first 10 bytes of row 25 contain control data relating to
the received page as shown in Table 1. The remaining 14
bytes are free for use by the microcomputer.
Integrated VIP and teletext decoder
(IVT1.1)
7 characters
for status
page information
10 bytes for
received
7
10
Fig.9 Basic page memory organization.
PACKET X / 24 STORED HERE IF R0D7 = 1
1
24 characters from page header
rolling when display page looked for
written by IVT hardware
alphanumerics white for normal
alphanumerics green when looking
MAIN PAGE DISPLAY AREA
fixed character
by microcontroller
PACKET X / 22
PACKET X / 23
free for use
14 bytes
14
24
17
for display page
Fig.10 Organization of the extension memory.
always rolling
8 characters
(time)
MBA274
PACKET X / 27 / 0
8
PACKET X / 24 if R0D7 = 0
PACKETS 8 / 30 / 0 to 15
ROW
20
21
22
23
24
25
to
0
1
2
3
4
5
MBA275 - 2
Product specification
SAA5244A
ROW
0
1
2