Programming Model

So, for example, the check-bits that correspond to the 64 bits of data found in normal mode (rwcb=0) at $00001000-$00001003 and $00001008-$0000100b are written and read in check-bit mode (rwcb=1) at location $00001003.

Connected to

Lower Falcon

Connected to

Upper Falcon

0

4

8

C

Normal View of Data (rwcb=0)

32 bits

0 1 2 3 4 5 6 7

Check-bit View (rwcb=1

11707.00 9701

Note that if test software wishes to force a single-bit error to a location using the rwcb function, the scrubber may correct the location before the test software gets a chance to check for the single-bit error. This can be avoided by disabling scrub writes. Also note that writing bad check- bits can set the elog bit in the Error Logger register. The writing of check-bits causes the Falcon to perform a read- modify-write to DRAM. If the location to which check- bits are being written has a single- or double-bit error, data in the location may be altered by the write check-bits operation. To avoid this, it is recommended that the derc bit also be set while the rwcb bit is set. A possible sequence for performing read-write check-bits is as follows:

3

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Motorola MVME2300 Series manual 11707.00