Integrated Device Technology, Inc.

Avigdor Willenz

Philip A Bourekas

Yeshayahu Mor

Scott Revak

Michael J Miller

Martin Emil Mueller

Yiftach Tzori

Steven M Eliscu

Yehayahu Mor

Danh LeNgoc

A structure and a method are provided to implement a reset scheme for an integrated circuit supporting a variety of testing and debugging equipment. The control and I/O pins of the integrated circuit are each set to a high impedance state when the signals of a reset pin and a mode pin are both asserted. If the signal on the mode pin remains asserted at the time the signal on the reset pin is negated, the control and I/O pins of the integrated circuit remain in the high impedance state until the next time the signal on the reset pin is asserted. Otherwise, the control and I/O pins of the integrated circuits are enabled upon negation of the signal on the reset pin. In one embodiment, the mode pin is multiplexed with an pin used for receiving interrupt signals during functional operation.

Flexible reset scheme supporting normal system operation, test and

A structure and a method are provided for refilling a block of memory words stored in a cache memory. The structure and method provide a read buffer to optimally match the processor speed with the main memory using read clock enable RdCEn and acknowledge (Ack) signals. The RdCEn signal is provided as each memory word is available from the main memory. The Ack signal is provided to indicate the time at which the processor may empty the read buffer at the processor clock rate without subsequently executing a wait cycle to wait for any remaining memory words in the block to arrive. The benefit of the present invention is obtained without incurring a performance penalty on the single word read operation.

Structure and method for multiple-level read buffer supporting optimal

A structure and a method provide data integrity for a multiprocessor system having a cache memory and a snoop tag cache. In one embodiment, the snoop tag cache copies the tags of a primary cache. Whenever a write operation occurs, the snoop tag cache is accessed to determine if the accessed tag matches a predetermined portion of the address of the memory location on which the write operation is performed. If so, a signal is sent to the CPU associated with the primary cache so that the corresponding entries in the primary cache and the snoop tag cache can be invalidated.

Method and structure for data integrity in a multiple level cache system

A method and a structure provide a flexible cache module for use in cache memory performance modelling. The flexible cache module can be configured by jumper connections or switches into a cache memory having a line size and a cache size selectable from a number of combinations of line size and cache size. In addition, the flexible cache module can also be configured as either a split cache memory, for implementing separate data and instruction caches, or a unified cache memory.

Structure and method for providing a cache memory of selectable sizes

A structure and a method are provided to implement a memory bus arbiter, in which separate priorities are provided to instruction and data reads from the main memory. In one embodiment in a microprocessor with an on-chip cache, the present invention provides an arbiter which yields the memory bus, in decreasing priority order, to an ongoing bus transaction, a 'direct memory access' (DMA) request, an instruction read resulting from a cache miss, a pending write request, and a read request, including reference to an uncacheable portion of memory and a data cache miss.

Memory operations priority scheme for microprocessors

In a microprocessor, two output pins are dedicated to providing information to assist in diagnosing problems relating to internal instruction and data caches or the software executing in the caches. The information on the pins is time-multiplexed. In a first phase, the pins indicate whether the data or instruction cache is accessed and whether a cache miss has occurred. In a second phase, the pins carry signals identifying the address reference which resulted in a cache miss.

Multiplexed status and diagnostic pins in a microprocessor with on-chip

A multiplexed address and data bus system provides a minimum pin count with byte enable and burst address counter support. The partitioning of the address bus includes separate byte enables to indicate specifically which bytes of the word are being accessed, and two independent address lines which can function as a counter to support the burst refill. Both block reads or single datum transfers are handled similarly: a single addressing phase with multiple data phases; and all addresses in the memory system; are derived directly from the same pins regardless of whether it is a block read or not. The system allows for low cost packaging while maintaining a variety of system capabilities.

Minimum pin-count multiplexed address/data bus with byte enable and

A method of programming a cache tag comparator by designing a semiconductor device's internal circuitry such that an input/output pin of the device may be programmed by an external resistor to ground that will indicate during the reset phase of the device that an alternate function for the pin is to be selected or that the pin itself is to be disabled.

Growing community of inventors

Campbell, CA, United States of America

Avigdor Willenz