SAA56XX Просмотр технического описания (PDF) - Philips Electronics

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SAA56XX

Enhanced TV microcontrollers with On-Screen Display (OSD)

Philips Electronics 

Philips Semiconductors

Enhanced TV microcontrollers with

On-Screen Display (OSD)

Product specification

SAA56xx

8.2 ROM protection and verification

SAA56xx devices have a set of security bits allied with

each section of the device, i.e. Program ROM, Character

ROM and Packet 26 ROM. The security bits are used to

prevent the ROM from being overwritten once

programmed, and also the contents being verified once

programmed.

The security bits can be programmed once only and

cannot be erased.

The SAA56xx security bits are set as shown in Fig.4 for

production programmed devices and are set as shown in

Fig.5 for production blank devices.

handbook, full pagewidthMEMORY

PROGRAM ROM

(128 or 192 kbytes)

CHARACTER ROM

(12 kbytes)

PACKET 26 ROM

(4 kbytes)

SECURITY BITS SET

USER ROM PROGRAMMING

DISABLED

VERIFY

ENABLED

DISABLED

ENABLED

DISABLED

ENABLED

GSA036

Fig.4 Security bits for production programmed devices.

handbook, full pagewidthMEMORY

PROGRAM ROM

(128 OR 192 kbytes)

CHARACTER ROM

(12 kbytes)

PACKET 26 ROM

(4 kbytes)

SECURITY BITS SET

USER ROM PROGRAMMING

ENABLED

VERIFY

ENABLED

ENABLED

ENABLED

ENABLED

ENABLED

GSA037

2001 Dec 13

Fig.5 Security bits for production blank devices.

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