MSM5718B70 Datasheet, PDF (9/40 Pages) OKI electronic componets – 18-Megabit RDRAM (2M x 9)

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MSM5718B70
Acknowledge Packet
Each RDRAM monitors the channel for a request to access its assigned memory range. The device
matching the address range requested then drives an acknowledge packet back to the master.
Bus- Bus-
Enable Ctrl
[0]
even
—
Ack[0]
[0]
odd
—
Ack[1]
Time
BusData (8:0)
—
—
Fig. 7 Acknowledge Packet¹
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.
The Ack[1:0] field in the Acknowledge packet carries the RDRAM's response to the request. If the
RDRAM is able to complete the operation as requested, it returns an okay response. If the RDRAM
is unable to complete the operation as requested, it returns a negative acknowledge response (Nack).
The encoding of the Ack[1:0] bits is shown in Table 4.
Table 4 Ack[1:0] Encodings
Ack [1:0]
00
01
10
11
Name
Non-
existent
Okay
Nack
Ack3
Description
Indicates passive acceptance of the request (WregB), or indicates that the addressed
device did not respond (all other commands).
Indicates that the request was accepted by the addressed (responding) device.
Indicates that the request could not be accepted because the state of the responding
device prevented an access at the fixed timing slot.
This should not be returned by this responding device. Initiating devices will, when
presented with this combination, have an undefined response.
In response to an acknowledged command, the RDRAM either drives a data packet back to the
master in the case of a read, or accepts a data packet from the master in the case of a write. Fig. 8 shows
an example of 16 byte read and write transactions. The actual timing from the end of a request packet
to data and acknowledge packets is adjustable through RDRAM register settings.
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