Hitachi, Ltd.

Hitachi Engineering Co., Ltd.

Mamoru Ohba

Mitsuru Watabe

Rika Minami

Koyo Katsura

Shigeki Morinaga

Hiroyuki Kida

Sanshiro Obara

Norio Nakagawa

Junichi Tatezaki

Hisashi Kaziwara

Takeshi Asai

To reduce the hardware of the graphics computer in size and reduce the cost of the hardware, the frame buffer and the main memory are united into one unit to process graphics data in the CPU. The frame buffer is arranged in the main memory, and the graphics computer includes a DMAC used to read pixel data from the frame buffer for display, a display used to receive the pixel data and display it on a display device, such as an LCD, etc., and memories used to store the procedure used by the CPU to draw the pixel data in the said frame buffer. Especially, the said memories are formed so that a single function procedure and 2 multifunction procedure can be selected to suit the drawing object. In addition, the single function procedure includes 2 line drawing procedure that uses data tables and 2 multivalue expansion procedure that uses a pattern table and a mask table. Since the frame buffer and the main memory are united into one unit, the CPU can be used to process graphics data. Thus, the graphics computer hardware is reduced in size and the cost of the hardware is reduced.

Graphics computer

To reduce the hardware of the graphics computer in size and reduce the cost of the hardware, the frame buffer and the main memory are united into one unit to process graphics data in the CPU. The frame buffer is arranged in the main memory, and the graphics computer includes a DMAC used to read pixel data from the frame buffer for display, a display used to receive the pixel data and display it on a display device, such as an LCD, etc., and memories used to store the procedure used by the CPU to draw the pixel data in the said frame buffer. Especially, the said memories are formed so that a single function procedure and a multifunction procedure can be selected to suit the drawing object. In addition, the single function procedure includes a line drawing procedure that uses data tables and a multivalue expansion procedure that uses a pattern table and a mask table. Since the frame buffer and the main memory are united into one unit, the CPU can be used to process graphics data. Thus, the graphics computer hardware is reduced in size and the cost of the hardware is reduced.

In a coprocessor system having a central processing unit (CPU), a floating-point processing unit (FPU) and a memory (RAM), coupled with each other through buses, when the CPU issues a save command to the FPU, the FPU discriminates the attribute, i.e., a long command or a short command, of a current command executed by the FPU upon receipt of the save command and the internal status thereof. In response to the discrimination result, the FPU interrupts the execution of the current command at once to start the execution of the received save command, when the current command is a long command, and the FPU executes the received save command after the completion of execution of the current command, if the current command is a short command. The attribute of a command is determined in advance on the basis of a time necessary for executing the command and a predetermined criterion provided therefor.

Method and apparatus for controlling timing of execution of saving and

The interface portion of a coprocessor is provided with a FIFO (First-In First-Out) buffer and means for accepting instructions in succession. Pipeline control of the instructions becomes possible in this way, and protocol means associated with a microprocessor is also provided.

Coprocessor executing pipeline control for executing protocols and

A digital pulse processing device is capable of selecting desired precision. The digital pulse processing device includes a counter group for counting pulses output from a pulse output device, the counter group having a plurality of counters A and B that can be separated from and coupled with each other, a mode control circuit for instructing separation and coupling of the counters A and B, and a control circuit for separating and coupling the counters A and B in accordance with the instruction of the mode control circuit. An overflow condition of the free-run counter B is detected using an overflow flag. Detection of an overflow is conducted by setting the flag when an overflow condition has occurred twice or more. The flag is reset by rewriting the state of the flag by a software. An overflow condition which has occurred for the first time is detected in the conventional manner and is treated as carry or borrow. A register is provided to hold the value of the counter B when a microcomputer reads in the counter B. In this way, even when .DELTA.A(i)=0, speed detection operation can be executed using the value of the counter B obtained synchronously with the counting of the counter A.

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Hitachi, Japan

Mamoru Ohba