¡ Semiconductor
MSM5718B70
PROTOCOL
The transaction protocol used in Rambus systems is built from several types of information packets.
These include the request, acknowledge, serial mode, and data packets.
Request Packet
A master device initiates a transaction by generating a six-byte request packet containing address,
control, and byte count information as shown in Fig. 6. The Op and OpX fields in the Request packet
contain a command that is used to instruct the RDRAM which operation is being requested. A
summary of these commands is shown in Table 3.
Bus- Bus-
Enable Ctrl
[0] —
even
Start Op[0]
[0]
odd
—
Op[1] Op[3]
[1]
even
—
OpX[1]
[1]
odd
—
Op[2]
[2]
even
—
OpX[0] ReqUnimp[5:4]
[2] —
odd
ReqUnimp[8:6]
Time
BusData (8:0)
Adr[9:2]
Adr[17:10]
Adr[26:18]
Adr[35:27]
Count[6, 4, 2]
ReqUnimp[3:0]
Count[7, 5, 3]
Count[1:0] Adr[1:0]
Fig. 6 Request Packet 1
Note: 1. A — in this diagram signifies that this pin is not used by this packet. If it is not used
by another packet, it is pulled to a logic zero value.
7