Daewoo DTU-14, Руководство по обслуживанию

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4. IC description
4-1. DW 5457 - *** ( SDA 5457 : SIEMENS TYPE )
(1) General Description
The SDA 545x is a single chip teletext decoder for decoding Worled System Telertext data as well as Video Program-
ming System ( VPS ), Program Delivery Control ( PDC ), and Wide Screen Signalling ( WSS ) data used for PALplus
transmissions ( line 23 ). Furthermore, the device provides an integrated C500 based general-purpose, fully 8051-
compatible microcontroller with television specific hardware features. The on-chip display unit for displaying ‘ Level 1.5
’ teletext data can be used for customer defined on-screen displays. Up to 10 display pages are available internally.
ROMless versions can be used together with external RAM.
The SDA 545x contains a slicer for VPS, WSS, PDC, and TTX, an accelerating acquisition hardware modul, a display
generator for “ Level 1.5 “ TTX data, and an 8 bit microcontroller running at 250 ns cycle time ( min. ). The controller
with dedicated hardware guarantees flexibility, does most of the internal processing of TTX acquisition, transfers data
to/from the external memory interface and receives/transmits data via I C-firmware user-interface. The slicer combined
with dedicated hardware stores TTX data in a VBI buffer of 746 Byte. The microcontroller firmware performs all the
acquisition tasks ( hamming - and parity - checks, page search and evaluation of header control bits ) once per field.
Additionally, the firmware can provide high-end Teletext-features like Packed-26-handling, FLOF, TOP ( in 8/10-page-
versions ) and listpages. The interface to the user software is optimized for minimal overhead ( see firmware data
sheet for details ).
The SDA 545xOTP contains 64KB-Program-ROM plus 6KB-Character-ROM, which both are ‘ one-time-programmable
‘ ( OTP ). It is pin-compatible to all the other ROM-types of SDA 545x. It can as such be used as a test circuit, a ramp-
up solution or even for small series in mass production.
(2) Features
Acquisition ( only SDA 545x )
Feature selection via special function register
Simultaneous reception of TTX, VPS, PDC, and WSS ( line 23 )
Fixed framing code for VPS and TTX
Acquisition during VBI
Direct access to VBI RAM buffer
Acquisition of packets x/0 to x/24, x/26, x/27, 8/30 ( firmware )
Assistance of all relevant checks ( firmware )
1-bit framing code error tolerance ( switchable )
Complete TTX-acquisition firmware with simple user interface
Display
Feature selectable via special function register
50/60/100/120-Hz display
Level 1.5 serial attribute display pages
Blanking and contrast reduction output
10 direct addressable display pages for SDA 5450
8 direct addressable display pages for SDA 5454 to SDA 5457
1 direct addressable display pages for SDA 5451 to SDA 5452
12 X 10-character matrix
96 character ROM (standard G0 character set )