High speed redundant data processing system

1. A data processing system comprising a data input, first and second data processing modules, and first and second data checking modules, wherein:

said first and second data processing modules are each arranged to perform substantially the same processing steps on data received at said data input, with each providing an output;

said first and second checking modules are arranged to compare the outputs of said first and second data processing modules and to output an error signal indicative of whether or not said first and second data processing modules have performed substantially the same processing steps on said data received at said data input;

said first and second checking modules are located on physically separate devices;

said first checking module has first and second inputs and said second checking module has first, second and third inputs;

said first and second inputs of said first checking module receive the outputs of said first and second data processing modules respectively;

said first checking module outputs first and second data signals corresponding to said outputs of said first and second data processing modules respectively and a first error signal indicative of whether or not said first and second data processing modules have performed substantially the same processing steps on said data received at said data input; and

said first and second inputs of said second checking module receive said first and second data signals from said first checking module and said third input of said second checking module receives said first error signal from said first checking module.

2. A data processing system as claimed in claim 1 , wherein said first and second data processing modules are located on physically separated devices.

3. A data processing system as claimed in claim 1 , further comprising a third checking module arranged to compare the outputs of said first and second data processing modules and to output a signal indicative of whether or not said first and second data processing modules have performed substantially the same processing steps on said data received at said data input.

4. A data processing system as claimed in claim 3 , wherein said third checking module has first, second and third inputs, wherein:

said second checking module outputs third and fourth data signals corresponding to said outputs of said first and second data processing modules respectively and a second error signal indicative of whether or not said first and second data processing modules have performed substantially the same processing steps on said data received at said data input; and

said first and second inputs of said third checking module receive said third and fourth data signals from said second checking module and said third input of said third checking module receives said second error signal from said second checking module.

5. A data processing system as claimed in claim 3 , wherein the third checking module is physically separated from each of said first and second checking modules.

6. A data processing system as claimed in claim 3 , wherein said signal indicative of whether or not said first and second data processing modules have performed substantially the same processing steps on said data received at said data input output by said third checking module is provided as an input to said first checking module.

7. A data processing system as claimed in claim 1 , wherein said signal indicative of whether or not said first and second data processing modules have performed substantially the same processing steps on said data received at said data input is provided as an input to at least one of said first and second data processing modules.

8. A data processing system as claimed in claim 1 , further comprising an error output flag, wherein said error output flag is set when any of said checking modules outputs a signal indicating that the first and second data processing modules have not performed substantially the same processing steps on said data received at said data input.

9. A data processing system as claimed in claim 1 , wherein the functionality of each of said first and second processing modules is defined by data stored in one or more memory modules.

10. A data processing system as claimed in claim 9 , wherein the functionality of said first processing module is defined by data stored in a first memory module and the functionality of said second processing module is defined by data stored in a second memory module.

11. A data processing system as claimed in claim 9 , wherein the data received at said data input contains a code referencing a memory location in said one or more memory modules defining the functionality of said data processing modules.

12. A method of data processing comprising the steps of:

passing a data input to both first and second data processing modules;

arranging for said first and second data processing modules to perform substantially the same processing on said data input;

arranging for first and second checking modules to output an error signal indicative of whether or not said first and second data processing modules have performed substantially the same processing steps on said data input;

passing outputs of both said first and second data processing modules to said first checking module; and

passing said outputs of said first and second data processing modules from said first checking module to said second checking module, together with a first error signal indicative of whether or not said first and second data processing modules have performed substantially the same processing steps on said data received at said data input,

wherein said first and second checking modules are located on physically separate devices.

13. A method as claimed in claim 12 , wherein said first and second data processing modules are located on physically separated devices.

14. A method as claimed in claim 12 , further comprising the step of passing the outputs of both said first and second data processing modules to a third checking module, wherein said third checking module is arranged to output an error signal indicative of whether or not said first and second data processing modules have performed substantially the same processing steps on said data input.

15. A method as claimed in claim 14 , further comprising the step of:

passing said outputs of said first and second data processing modules from said second checking module to said third checking module, together with a second error signal indicative of whether or not said first and second data processing modules have performed substantially the same processing steps on said data received at said data input.

16. A method as claimed in claim 14 , wherein the third checking module is physically separated from each of said first and second checking modules.

17. A method as claimed in claim 14 , further comprising the step of providing said signal indicative of whether or not said first and second data processing modules have performed substantially the same processing steps on said data received at said data input output by said third checking module as an input to said first checking module.

18. A method as claimed in claim 12 , further comprising the step of providing at least one of said signals indicative of whether or not said first and second data processing modules have performed substantially the same processing steps on said data received at said data input as an input to at least one of said first and second data processing modules.

19. A method as claimed in claim 12 , wherein said data input includes a code referencing a memory location in one or more memory modules to which said first and second data processing modules have access, said memory location defining the functionality of said data processing modules.