Stmicroelectronics Gmbh

Stmicroelectronics (research & Development) Limited

Paul Elliott

Andrew R Dellow

Peter Bennett

Tariq Kurd

Mark Trimmer

Tom Ryan

Matt Hutson

A monitor includes a register configured to store at least two contexts and a context change value. A context selector is configured to select at least one of the two contexts for context monitoring. The selection is made dependent on whether the context change value matches a first part of a memory access address.

Hardware monitor with context switching and selection based on a data memory access and for raising an interrupt when a memory access address is outside of an address range of the selected context

A semiconductor integrated circuit for the processing of conditional access television signals that includes an input interface for receiving encrypted television signals and an output interface for output of decrypted television signals. The semiconductor integrated circuit is provided with some functionality restricted in some way by preventing one or more hardware circuit elements from operating, such as an MPEG decoder, display engine, IO ports or main CPU. To enable the functionality, a subscriber must pay for a service and then receives an encrypted message broadcast to the semiconductor integrated circuit that is decrypted and instructs functionality to be turned on or off.

Method of providing an audio-video device to an end user

A semiconductor integrated circuit includes a hardware mechanism arranged to ensure that associations between instructions and data are enforced so that a processor cannot fetch data from an instruction that is not authorized to do so. A Memory Protection Unit stores entries comprising instructions and associated data memory ranges. A hardware arrangement impairs the operation of the circuit if the processor attempts to make a data fetch from an instruction that is outside the range associated with data in a Memory Protection Unit. Such functioning may be by issuing a chip reset. The Memory Protection Unit may be implemented in a Memory Management Unit having an extension so as to store a validity flag. The validity flag may only be set by a secure process such as the CPU well entrusted code or by a separate trusted hardware source.

Integrated circuit with restricted data access

Security integrated circuit

A clock source selector for selecting either a first clock signal A or a second clock signal B in accordance with a switch request signal includes three retiming circuits each consisting of two clocked flip-flops. The switch request signal is first retimed relative to clock A to give a signal P, is then retimed relative to clock B to give a signal Q, and finally is retimed relative to clock A to give a signal R. Selector circuitry operates such that when signal Q is asserted, the second clock signal B is output, when neither signal P nor signal R, as combined by a NOR gate, are asserted, the first clock signal A is output, and at other times a zero level is output. The clock source selector can be used in an integrated circuit to form a glitch-free multiplexer.

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Bristol, United Kingdom

Paul Elliott