Abstract: A data processing system (10) capable of burst transfers having an external bus interface (30) which allows termination of a burst transfer prior to completion of the burst transaction. The present invention offers a method of terminating a burst transaction without the addition of wait states, and further allows termination to effectively interrupt the burst transaction rather than waiting for burst completion. In one embodiment, on the negation of a burst request signal during a burst transfer, external bus interface (30) terminates the burst transfer without waiting for the completion of the burst transaction.

Abstract: A data processing system (20) having a burst address generator (BAG) 55, with a programmable transaction mode applicable to both cache and pre-fetch architecture types. BAG 55 asserts a data acknowledge (DTACK) signal to end a burst transfer on either a physical boundary, as in pre-fetch mode at the end of a row in a memory device, or a limit detection, as in cache mode where the limit is determined by the length of a cache line. BAG 55 increments the burst address internally, and for operations in pre-fetch mode, the user determines if the incremented address is provided external to data processor (22).

Abstract: A data processing system (20) having programmable chip select signal negation. A user programmable "NEGATE EARLY" value generates a chip select negation one bus cycle before the end of a transaction, giving an external device additional time to disconnect from the current bus cycle before the start of the next bus cycle. Early negation of a chip select signal provides an efficient method of interface with slower devices while providing adding functionality to the chip select signal.

Abstract: A data processing system (20) having a high performance chip select (HPCE) signal, which is functionally programmable to remain asserted for a predetermined number of bus cycles based on an access duty cycle. Bits in an option register (52) allow the user to program HPCE for maintained assertion always, never, or for a number of cycles after a last valid address match. Continued assertion reduces access time to an external device allowing the user to determine the trade-off between high speed access and low power consumption. Additionally, a speculative burst access is made without regard to match criteria, allowing a device to prepare for access while data processor (22) determines the next device to access. Here a load burst address (LBA) signal is speculatively provided to an activated device, and where the next access is to another device, the speculative access is aborted.