5

MCECC

1.Stop all scrub operations by clearing all of the STON bits and setting all of the STOFF bits in the Scrub Time On/Time Off Register.

2.Set the DERC and RWCKB bits in the Data Control Register.

3.Perform the desired read and/or write checkbit operations.

4.Clear the DERC and RWCKB bits in the Data Control Register.

5.Perform the desired testing related to the location/locations that have had their checkbits altered.

6.Allow the scrubber to proceed by restoring the STON and STOFF bits to their original state.

ZFILL ZERO FILL memory, when set, forces all zeros to be written to the DRAM during any kind of write cycle or scrub cycle. It is intended to be used with the zero-fill function. Refer to the section on Initialization at the end of this chapter. This bit should be cleared for normal system operation.

DERC DISABLE ERROR CORRECTION, when set to one, disables the MCECC from correcting single bit errors. Specifically, read data is presented to the local MC68060 data bus unaltered from the DRAM array. Less-than-line write data performs a read-modify-write without correcting single bit errors that may occur on the read portion of the read-modify-write. Note that DERC does not affect the generation of check bits. DERC should be cleared during normal system operation. DERC also allows the write portion of a read-modify-write to happen regardless of whether or not there is a multiple bit error during the read portion of the read-modify-write. DERC also affects scrub cycles.

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Motorola MVME172 manual Mcecc