SAA5250 Ver la hoja de datos (PDF) - Philips Electronics

Número de pieza

componentes Descripción

Fabricante

SAA5250

Interface for data acquisition and control (for multi-standard teletext systems)

Philips Electronics 

Philips Semiconductors

Interface for data acquisition and control

(for multi-standard teletext systems)

Register organization

R0 register

Table 3 R0 Register contents

R04

SLOW/FAST MODE

0 = slow mode

1 = fast mode

R03

PARITY

0 = no parity control

1 = odd parity

Product specification

SAA5250

R02 TO R00

USED PREFIXES

000 = DIDON long

001 = DIDON medium

010 = DIDON short

011 = not used

100 = U.K. teletext

101 = NABTS

110 = without prefix

111 = without prefix

handbook,CfuEllEpFaAgeXwidth

FC

DIDON

short

FC

DIDON

medium

FC

DIDON

long

FC

NABTS

FC

magazine and row address group

MRAG

A

format

A1

A2

A1

A2

A3

CI

A1

A2

A3

CI

Fig.3 Five prefixes.

format

PS

MGH077

All of the bytes (see Fig.3) are Hamming protected. The hatched bytes are always stored in the memory in order to be

processed by the CPU (see section ‘Prefix processing’). In the mode without prefix all of the bytes which follow the

framing code are stored in the memory until the end of the data packet, the format is then determined by the contents of

the R3 register.

If R03 = 0; no parity control is carried out and the 8-bits of the incoming data bytes are stored in the fifo memory.

If R03 = 1; the 8th bit of the bytes following the prefix (data bytes) represents the result of the odd parity control.

If R04 = 0; the device operates in the slow mode. The CIDAC retrieves data from the user selected magazine (see

section ‘R1 and R2’) and without searching for a start to a page stores the data into the FIFO memory.

January 1987

7

Share Link: