National Semiconductor Corporation

Aharon Ostrer

Ohad Falik

Gideon Intrater

Yair Baydatch

Rami Saban

Alberto Sandbank

Gadi Erlich

Dan Biran

Gigi Baror

Moti Beck

Benny Konstantin

Jonanthan Levy

Elliot Cohen

Yair Hadas

Alon Shackam

Boaz Shahar

A data processing technique with which a CPU core accesses memory devices over a bus. Some of the memory devices are on-chip, and some may be off-chip. In order to optimize its operation, the CPU core accesses the on-chip devices via a core buffer interface unit ('BIU') which has been tuned to on-chip operation. Off-chip devices communicate with the CPU core via a system BIU which translates the on-chip bus transactions to meet the off-chip device requirements.

Microprocessor-based data processing apparatus that commences a next

Binary multiplication is performed with existing data processing apparatus to which only minor modifications are required. One operand and a partial product are stored in existing latches of a CPU. The second operand is stored in a shift register which is added to the CPU. The data in the shift register is shifted from the LSB to the MSB, with a '0' being loaded into the LSB. As the bits in the first operand are designated in sequence, the value of the partial product is increased by the value in the shift register if the designated bit is a '1'. After the sequencing has designated all the bits of the first operand, the partial product is taken to be the product of the multiplication.

Binary multiplication implemented by existing hardware with minor

A method and apparatus for prechecking (probing) the validity of an access request for writing result data to an external system prior to executing the instruction that generates the result is provided. This allows instruction execution to continue uninterrupted in the event that the write is allowed. The microprocessor's Address Unit issues a 'probe' request to the Memory Management Unit (MMU) via an internal bus while saving the instruction's virtual address in a virtual address buffer local to the Address Unit. The MMU checks the validity of the 'probe' request without converting the virtual address to a physical address and issues an access grant signal which is saved by the microprocessor's Execution Unit for subsequent use. The Execution Unit processes the data in parallel to the MMU checking the validity of the probe request. If the virtual address associated with the probe request resulted in an access grant signal, then the Execution Unit issues a write request while the virtual address previously stored in the Address Unit is sent to the MMU for translation to a physical address. Both the write data and the physical address are stored in a buffer in the microprocessor's Bus Interface Unit (BIU) for subsequent transfer to an external system. The data is then written to the external system at the physical address provided by the BIU.

Method of prechecking the validity of a write access request

Growing community of inventors

Hertzelia, Israel

Aharon Ostrer