User`s guide

The XMI
2.4.3 Write Data Cycles
A function code of 0010 identifies an XMI write data cycle. Write data
cycles immediately follow the XMI command cycle during an XMI write
transfer. During this cycle, the commander drives its ID on XMI ID<5:0>
L and drives write data on D<63:0> L. The full 64 bits of data are used
during quadword-length or larger writes. For longword-length writes, only
the lower longword D<31:0> L is used and the value of the upper longword
is unspecified. In either case, the full 64 bits are used when checking XMI
P<2:0> L.
2.4.4 Good Read Data (GRD) and Corrected Read Data (CRD) Response
Cycles
Function codes 1000 through 1111 are used to identify return data
in response to a Read, Interlock Read, Ownership Read, or IDENT
transaction. The Good Read Data response (GRDn, codes 1000 – 1011)
indicates that the quadword of data is error-free. The Corrected Read Data
response, CRDn, codes 1100 – 1111) indicate that the corresponding
quadword of data stored in memory contained a single-bit error which was
successfully corrected using ECC prior to shipment on the XMI. Both types
of read data responses contain a sequence ID located in XMI F<1:0> L,
which is used to identify when a read data cycle has been lost due to an
XMI parity error.
During a read data response cycle, the responder drives the commander’s
ID on XMI ID<5:0> L and read data on D<63:0> L. All 64 bits of data
are used during quadword-, octaword-, and hexword-length reads. For
longword-length reads, only the lower longword (D<31:0> L) is used. In
this case, the value of the upper longword is unspecified. In either case,
the full 64 bits are used when checking XMI P<2:0> L.
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