82375EB datasheet(79/131 Pages) INTEL

79 / 131 page

82375EBSB

290477 – 59

Figure 17 Master Initiated Termination (Master Abort)

51102 Target Initiated Termination

The PCEB supports two forms of target-initiated termination

Disconnect A disconnect termination occurs when the target is unable to respond within the latency

guidelines of the PCI specifications Note that this is not usually done on the first data phase

Retry Retry refers to a termination requested because the PCEB is currently in a state that makes it unable

to process the transaction

Figure 18 and Figure 19 show four types of target-initiated terminations The PCEB initiates a disconnect for

PCI cycles destined to EISA after the first data phase due to incremental latency requirements The difference

between disconnect and retry is that the PCEB does not assert TRDY

for the retry case This instructs the

initiator to retry the transfer at a later time No data is transferred in a retry termination since TRDY

and

IRDY

are never both asserted The PCEB retries a PCI initiator when

the PCEB buffers require management activity

the PCEB is locked and another PCI device attempts to select the PCEB without negating PLOCK

during

the address phase

the EISA Bus is occupied by an EISAISA master or DMA

Target abort is another form of target-initiated termination Target abort resembles a retry though the target

must also negate DEVSEL

along with assertion of STOP

As a target the PCEB never generates a target

abort

As a master If the PCEB receives a target abort it relinquishes the PCI Bus and sets the Received Target

Abort Status bit in the PCI Status Register to a 1

82375EB датащи(PDF) 79 Page - Intel Corporation