
Sun Microelectronics
110
UltraSPARC User’s Manual
5.
UltraSPARC
2
drives the value of its port_ID register on SYSDATA
6.
SC sends S_RAS to UltraSPARC
1
(the initiator)
7.
UltraSPARC
1
reads the port_ID of UltraSPARC
2
from SYSDATA
Table 7-13 shows the number of outstanding NonCachedRead transactions that
each UltraSPARC model supports.
7.8.2 NonCachedBlockRead (P_NCBRD_REQ)
Noncached Block Read Request. UltraSPARC reads 64 bytes of noncached data
with this transaction. Generated by UltraSPARC for block read of a noncached
address space.
The data is aligned on 64-byte boundary (PA<5:4>=0). SC sends an S_RBU (Read
Block Unshared) reply, which directs the requesting UltraSPARC to receive the
data from SYSDATA.
Table 7-13 shows the number of outstanding NonCachedBlockRead transactions
that each UltraSPARC model supports.
7.8.3 NonCachedWrite (P_NCWR_REQ)
Noncached Write. Generated by UltraSPARC to write a noncached address space.
The address is aligned on 16-byte boundary. Any number between 0..16 bytes can
be written, as specified by a 16-bit bytemask in the request. Typically, the data is
written to slave devices that support writes with arbitrary byte masks (mainly
graphics devices). A bytemask of all zeros indicates a no-op at the slave.
SC issues S_WAS to the requesting UltraSPARC to drive the data on SYSDATA.
Table 7-13
Supported Number of Outstanding NonCachedRead Transactions
UltraSPARC-I
UltraSPARC-II
Number
1
1
Table 7-14
Supported Number of Outstanding NonCachedBlockRead Transactions
UltraSPARC-I
UltraSPARC-II
Number
1
2
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