US 6,324,628 B1 · Programming flash in a closed system

Abstract

A method and a system for reprogramming a closed device are disclosed. In one embodiment, the system contains an external memory coupled to a limited access device. The limited access device includes a processor, an internal memory, a select control circuit, an internal data bus, and an external data bus. The internal memory is not accessible except through predefined input and output ports of the select control circuit, which are accessible external to the closed device. The select control circuit selects the external memory as primary memory in response to assertion of a control signal and selects the internal memory as primary memory in response to deassertion of a control signal. The internal data bus transports data within the limited access device which includes the internal memory and the select control circuit and the external data bus transports data between the select control circuit and the external memory.

Claims20

Dependent claims

A system comprising:

an external memory;
and
a closed device, coupled to said external memory, wherein said closed device includes:
a processor coupled to said external memory;
an internal memory coupled to said processor, wherein said internal memory is not accessible except access through predefined input and output ports that are internal to said closed device;
a select control circuit coupled to said processor and configured to select said external memory as primary memory in response to assertion of an external control signal and to select said internal memory as primary memory in response to a deassertion of said external control signal;
an internal data bus, coupled with said select control circuit, said processor, and said internal memory, said internal data bus residing solely within said closed device with no external access;
and
an external data bus, coupled with said select control circuit and said external memory, configured to transport data between said select control circuit and said external memory.

6 more elements

Dependencies are inferred from the claim text.

Programming flash in a closed system

Life of this patent

Programming flash in a closed system

Life of this patent

Abstract

Claims20