Renesas Electronics Corporation

Renesas Technology Corp.

Other

Denso Corporation

Takeshi Kataoka

Toshihiro Tanaka

Kazumasa Yanagisawa

Yutaka Shinagawa

Kazufumi Suzukawa

Eiichi Ishikawa

Takanaga Yamazaki

Hiromichi Yamada

Teppei Hirotsu

Shunichi Iwata

Yasuhiro Nakatsuka

Yasushi Akao

Keiichi Kurakazu

Masafumi Inoue

Hisakazu Sato

Teruaki Sakata

Hirokazu Komori

Kesami Hagiwara

Satoshi Tanaka

Yoshikazu Kiyoshige

Yasuo Sugure

Hideo Kubota

Akihiko Tomita

Takahiro Gotoh

Tomomi Ishikura

Kazuya Hirayanagi

Seiji Takeuchi

Yosuke Murayama

Mitsuhiro Miyazaki

Tatsuo Nakai

Yuuichi Abe

Masayasu Ohizumi

A high-performance information processing technique permitting updating of an instruction buffer ready for effective prefetching to branch instructions and returning to the subroutine with a small volume of hardware is to be provided at low cost. It is an information processing apparatus equipped with a CPU, a memory, prefetch means and the like, wherein a prefetch address generator unit in the prefetch means decodes a branching series of instructions including at least one branched address calculating instruction and branching instruction to a branched address out of a current instruction buffer storing the series of instructions currently accessed by the CPU, and thereby looks ahead to the branching destination address. The information processing apparatus further comprises a RTS instruction buffer for storing a series of instructions of the return destinations of RTS instructions, and series of instructions stored in the current instruction buffer are saved into the RTS instruction buffer.

Apparatus for calculating and prefetching a branch target address

A semiconductor integrated circuit has a central processing unit and a rewritable nonvolatile memory area disposed in an address space of the central processing unit. The nonvolatile memory area has a first nonvolatile memory area and a second nonvolatile memory area, which memorize information depending on the difference of threshold voltages. The first nonvolatile memory area has a maximum variation width of a threshold voltage for memorizing an information set larger than that of the second nonvolatile memory area. The first nonvolatile memory area can be prioritized to expedite a read speed of the memory information, and the second nonvolatile memory area can be prioritized to guarantee the number of times of rewrite operation of memory information.

Semiconductor integrated circuit

A semiconductor integrated circuit has a central processing unit and a rewritable nonvolatile memory area disposed In an address space of the central processing unit. The nonvolatile memory area has a first nonvolatile memory area and a second nonvolatile memory area, which memorize information depending on the difference of threshold voltages. The first nonvolatile memory area has the maximum variation width of a threshold voltage for memorizing information set larger than that of the second nonvolatile memory area. When the maximum variation width of the threshold voltage for memorizing information is larger, since stress to a memory cell owing to a rewrite operation of memory information becomes larger, it is inferior In a point of guaranteeing the number of times of rewrite operation; however, since a read current becomes larger, a read speed of memory information can be expedited. The first nonvolatile memory area can be prioritized to expedite a read speed of the memory information and the second nonvolatile memory area can be prioritized to guarantee the number of times of rewrite operation of memory information more.

A semiconductor integrated circuit has a central processing unit and a rewritable nonvolatile memory area disposed in an address space of the central processing unit. The nonvolatile memory area has a first nonvolatile memory area and a second nonvolatile memory area, which memorize information depending on the difference of threshold voltages. The first nonvolatile memory area has the maximum variation width of a threshold voltage for memorizing information set larger than that of the second nonvolatile memory area. When the maximum variation width of the threshold voltage for memorizing information is larger, since stress to a memory cell owing to a rewrite operation of memory information becomes larger, it is inferior in a point of guaranteeing the number of times of rewrite operation; however, since a read current becomes larger, a read speed of memory information can be expedited. The first nonvolatile memory area can be prioritized to expedite a read speed of the memory information and the second nonvolatile memory area can be prioritized to guarantee the number of times of rewrite operation of memory information more.

A semiconductor integrated circuit has a central processing unit and a rewritable nonvolatile memory area disposed in an address space of the central processing unit. The nonvolatile memory area has a first nonvolatile memory area and a second nonvolatile memory area, which memorize information depending on the difference of threshold voltages. The first nonvolatile memory area has the maximum variation width of a threshold voltage for memorizing information set larger than that of the second nonvolatile memory area. When the maximum variation width of the threshold voltage for memorizing information is larger, since stress to a memory cell owing to a rewrite operation of memory information becomes larger, it is inferior in a point of guaranteeing the number of times of rewrite operation; however, since a read current becomes larger, a read speed of memory information can be expedited. The first nonvolatile memory area can be prioritized to expedite a read speed of the memory information and the second nonvolatile memory area can be prioritized to guarantee the number of times of rewrite operation of memory information.

Semiconductor integrated circuit having buses with different data transfer rates

A microcontroller in which an increase in hardware is suppressed and data correction capability for software error of RAM can be improved is provided. A microcontroller which performs processing according to a program includes a CPU and a RAM for storing data processed by the CPU, wherein multiplexed regions are defined in the RAM, and when these regions are accessed, an access to an address outputted by the CPU and a copy access to an address obtained by adding or subtracting a certain value to or from the address outputted by the CPU are performed. By this means, the same data can be stored in a plurality of regions and the reliability can be improved.

Microcontroller and RAM

In a multiprocessor, one of two local memories can be accessed at a high speed by one of the two processors and also accessed by the other processor. In a multiprocessor, first and second local memories are coupled to first and second processors via first and second local buses. First and second bus bridges are coupled to a system bus and the first and second local buses. First and second bus interface units are coupled to the system bus and the first and second local memories. A high-speed access is made from the first processor to the first local memory via the first local bus. The first local memory is also accessed from the first processor via the first local bus, the first bus bridge, the system bus, and the first and third ports of the second bus interface unit and from the second processor via the second local bus, the second bus bridge, the system bus, and the second and third ports of the first bus interface unit. A high-speed access is made from the second processor to the second local memory via the second local bus. The second local memory is also accessed from the second processor via the second local bus, the second bus bridge, the system bus, and the second and third ports of the first bus interface unit and from the first processor via the first local bus, the first bus bridge, the system bus, and the first and third ports of the second bus interface unit.

Data processing system

This invention provides a data processing system capable of performing an interrupt exception handling routine as many times as the number of times of occurrence of a request event for the same interrupt exception handling routine if the request event occurs a plurality of times. A software interrupt counter or a hardware interrupt counter for retaining the number of times of occurrence of an interrupt request generation event counts up when a software processing which generates a software interrupt or a hardware event that generates a hardware interrupt occurs, and counts down when a CPU performs a processing for removing the interrupt request. If the value of the software interrupt counter and the value of the hardware interrupt counter are not zero, a software interrupt request signal and a hardware interrupt request signal to the CPU are asserted.

Data processing system having a data transfer unit for converting an integer into a floating-point number when tranferring data from a peripheral circuit to a memory

The present invention prevents a data processor from undesirable operation stop due to an overflow of a plurality of register banks. A status register includes an overflow flag to indicate an overflow of the plurality of register banks. When an interrupt exception occurs in a state in which data has been saved to all banks of the register banks, and the accepted interrupt exception is permitted to use the register banks, a central processing unit saves data of a register set to a stack area and reflects an overflow state in the overflow flag. When the overflow flag indicates an overflow state, if data restoration from the register banks to the register set is directed, the central processing unit restores the data from the stack area to the register set.

Data processor employing register banks with overflow protection to enhance interrupt processing and task switching

A data processor including a central processing unit and a plurality of direct map cache memories ( ) has a plurality of area designating circuits ( ) for variably designating location and size of address area in the memory space managed the central processing unit and partially overlaps the address area designated by a plurality of area designating circuits. Thereby, the overlapped area (Eco) has a function as the 2-way set associative cache memory in combination with a plurality of cache memories. For the non-overlapping area, respective cache memory functions as the direct map cache memory. It is previously judged to attain the necessary data processing capability by arranging which processing routine to which address area and then executing such routine with what processing speed. Thereby, when cache object area is assigned to a plurality of cache memory, a plurality of cache memories are combined as a set associative cache for operation to the task which particularly requires high speed operation or to the data. As a result, the system can be optimized by improving the cache hit rate of the necessary area.

Data processor and data processing system

Growing community of inventors

Tokyo, Japan

Takeshi Kataoka