Table 2.12 Parallel Protocol Request Message Implied Agreement - Fujitsu MBA3073 SERIES Technical Manual

Table 2.12 PARALLEL PROTOCOL REQUEST message implied agreement
Responding SCSI device PARALLEL
PROTOCOL REQUEST response
Non-zero REQ/ACK offset
REQ/ACK offset equal to zero
Non-zero TRANSFER WIDTH
EXPONENT
TRANSFER WIDTH equal to zero
Protocol options equal to 0h and
transfer period factor equal to 9h
IU_REQ, DT_REQ, and QAS_REQ
Equal to zero
DT_REQ equal to one
IU_REQ, and DT_REQ equal to one
MESSAGE REJECT message
Parity error (on responding message)
Unexpected bus free
(as a result of the responding message)
No response
(1) Target initiated PARALLEL PROTOCOL REQUEST negotiation
If the TARG recognizes that PARALLEL PROTOCOL REQUEST negotiation is required, it not
sends a PARALLEL PROTOCOL REQUEST message to the INIT.
(2) Initiator initiated PARALLEL PROTOCOL REQUEST negotiation
If the INIT recognizes that PARALLEL PROTOCOL REQUEST negotiation is required, it
creates an attention condition and sends a PARALLEL PROTOCOL REQUEST message to begin
the negotiating process. After successfully completing the MESSAGE OUT phase, the TARG
shall respond with a PARALLEL PROTOCOL REQUEST message or a MESSAGE REJECT
message.
If an abnormal condition prevents the TARG from responding with a PARALLEL PROTOCOL
REQUEST message or with a MESSGE REJECT message then both SCSI devices shall use the
eight-bit/asynchronous data transfer mode with all the protocol options bits set zero to indicate ST
DATA IN and ST DATA OUT phases between the two SCSI devices.
C141-C015
Implied agreement
Synchronous transfer (i.e., Each SCSI device transmits data
with a period equal to or greater than and a REQ/ACK offset
equal to or less than the negotiated values received in the
responding SCSI device's PPR message).
Asynchronous transfer
Wide transfer (i.e., the initiator and the target transmit data
with a transfer width equal to the responding device's transfer
width). If the initiating SCSI device does not support the
responding SCSI device's TRANSFER WIDTH EXPONENT
then the initiating SCSI device shall MESSAGE REJECT the
PPR message.
Eight-bit data
Eight-bit/asynchronous data transfer with PROTOCOL
OPTIONS field set to 0h
ST DATA IN and ST DATA OUT phases to transfer data
DT DATA IN and DT DATA OUT phases transfer data with
IU RC
DT DATA IN and DT DATA OUT phases with information
units
Eight-bit/asynchronous data transfer with PROTOCOL
OPTIONS field set to 0h
Eight-bit/asynchronous data transfer with PROTOCOL
OPTIONS field set to 0h
Eight-bit/asynchronous data transfer with PROTOCOL
OPTIONS field set to 0h
Eight-bit/asynchronous data transfer with PROTOCOL
OPTIONS field set to 0h
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