International Business Machines Corporation

Jorge E Lenta

Mark William Kellogg

Christopher M Herring

Daniel P Fuoco

Chester A Heath

Mitchell E Medford

The present invention relates to a computer system and method of using the same in which add-on memory cards are provided which have error correction code logic on the card and logic to do partial writes of data words. The system has a central processing unit (CPU), and a BUS interconnecting the CPU and the add-on memory cards which are configured to write data and read data from the add-on memory. The system is further configured (either within the CPU or as a separate function) to generate parity bits associated with each of the bytes of data the CPU writes to the add-on memory and to read parity bits associated with data the CPU reads from the add-on memory and regenerate new parity bits and compare the newly generated parity bits with the original parity bits to detect data errors on data read from the add-on memory. The add-on memory has ECC logic to identify any byte having a single bit error in the data bytes or the parity bits written by the CPU to the add-on memory and to correct all single bit errors in data read from the add-on memory to the CPU.

Memory card, computer system and method of operation for differentiating

The present invention provides a computer system and method of using the same. Add-on memory cards for the system are provided which cards have error correction code logic on the card, and logic to do partial writes of data words. The system has a central processing unit (CPU), a BUS interconnecting the CPU and the add-on memory cards. The CPU or associated components are configured to write data and read data from the add-on memory as several data bytes constituting data words. The system is further configured either within the CPU or as a separate function to generate parity bits associated with each of the bytes of data the CPU writes to the add-on memory and to read parity bits associated with data the CPU reads from the add-on memory and regenerate new parity bits and compare the newly generated parity bits with the original parity bits to detect data errors on data read from the add-on memory. The system itself does not contain error correction code (ECC). The add-on memory has ECC logic to identify any byte having a single bit error in the data bytes or the parity bits written by the CPU to the add-on memory and to correct all single bit errors in data read from the add-on memory to the CPU. The error correcting code includes logic to generate parity bits in the data bytes written by the CPU to the add-on memory and logic to compare the parity bits written by the CPU with those generated by the error correcting code logic.

Error correction code on add-on cards for writing portions of data words

This invention relates to a personal computer having enhanced memory access capabilities, a memory element enabling such enhancement, and a method of operation of a personal computer. The invention contemplates that enhanced capabilities will be attained by enabling a choice between error detection technologies used.

Personal computer wherein ECC and partly error checking can be

A computer system in which peripherals greater in number than the number of DMA channels provided in the system can all have DMA access. Some of the DMA channels are dedicated to certain ones of the peripherals, while others, termed 'programmable' DMA channels, are shared by remaining ones of the peripherals. Each peripheral having DMA access has a channel priority value. When a peripheral wants DMA access, it transmits its channel priority value onto an arbitration bus. The winning channel priority value is then compared with prestored DMA channel assignment values. If the comparison is successful, the corresponding peripheral is given a DMA channel corresponding to the DMA Channel assignment value with which the comparison was successful.

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Boca Raton, FL, United States of America

Jorge E Lenta