Memory system
OwnerDavid Stuart Gordoninventor
Life of this patent
Estimating the term…
Abstract
A computer system is described having a proxy DMA unit which is used as an intermediary during direct memory access operations performed by a conventional DMA controller. The proxy DMA unit is provided with check summing circuitry which calculates a check sum for the data transferred between system memory and an external peripheral device. The check sum is subsequently used by the computer system to validate the data when it is read back to the system memory via the proxy DMA unit thus generating a second check sum. If the two check sums are the same the data is uncorrupted whereas if they are different the data is corrupted and remedial procedures can be initiated.
Claims49
A computer system comprising:
- a processing unit for controlling the operation of the computer system;
- system memory for storing data used by the computer system;
- a system bus for connecting the processing unit to the system memory;
- a DMA controller coupled to said system bus for controlling data transfers between the system memory and an external peripheral device;
- a further DMA unit which is coupled to said system bus;
- wherein said processing unit is operable to program said DMA controller to write data to or request data from said further DMA unit;
- wherein said further DMA unit comprises:
- writing and reading circuitry for writing data to or reading data from said system memory in accordance with the data received or requested from said DMA controller;
- output circuitry for outputting data read from said system memory to said DMA controller;
- and
- calculating circuitry for calculating check data for the data written to or read from the system memory.
A proxy DMA unit for use in calculating check data for data transferred by a DMA controller between system memory of a computer system and an external peripheral device, the proxy DMA unit comprising:
- circuitry for receiving data or requests for data from said DMA controller;
- writing and reading circuitry for writing data to or reading data from said system memory in accordance with the data received or requested from said DMA controller;
- output circuitry for outputting data read from said system memory to said DMA controller;
- and
- calculating circuitry for calculating check data for the data written to or read from the system memory.
A processing unit operable to control the transfer of data between the system memory of a computer system and an external peripheral device using a DMA controller and a further DMA unit, the processing unit being characterised in that it is operable to program said DMA controller to write data to or request data from said further DMA unit instead of from said system memory.
A computer instruction carrier medium carrying instructions for causing a programmable processing apparatus to control a data transfer operation between system memory of a computer system and an external peripheral device using a DMA controller and a further DMA unit, the instructions comprising instructions for programming said DMA controller to write data to or request data from said further DMA unit instead of from said system memory.
A method of operating a computer system having a processing unit, a system memory, a DMA controller and a further DMA unit, the method comprising the steps of:
- programming said DMA controller to write data to or request data from said further DMA unit;
- writing data or reading data from said system memory and outputting read data to said DMA controller in accordance with the data received or requested from said DMA controller;
- and
- calculating check data for the data written to or read from the system memory.
Dependencies are inferred from the claim text.