Final answer:
It is true that PCI transfer lengths are indeterminate and that PCI-X burst lengths are not predetermined at the time of the request. PCI uses an indeterminate transfer length mechanism, while PCI-X uses burst transfers where the length is decided at the beginning of the transaction.
Step-by-step explanation:
The statement that PCI transfer lengths are indeterminate and PCI-X burst lengths are not known at the time of the request is true. In PCI, data is transferred using a mechanism where the length of the data transfer is not determined in advance; this is what is meant by indeterminate transfer lengths.
In contrast, PCI-X, which is an enhanced version of PCI, allows for efficient bus usage by employing burst transfers where the size of the data transfer is fixed at the start of a transaction. However, this does not necessarily mean that the burst length is known ahead of time; it is decided at the initiation of the burst transfer.