Hitachi, Ltd.

Rika Minami

Mitsuru Watabe

Mamoru Ohba

Koyo Katsura

Sanshiro Obara

Shigeki Morinaga

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.

An analog-digital converting device is designed such that when an operation of converting a special analog signal into a digital signal and an operation of converting another analog signal into a digital signal are instructed concurrently, priority is given to the conversion operation of the special analog signal, The analog-digital converting device includes an analog multiplexer having a main channel and a sub channel, a sample holder, an AD converter, a conversion result register having a plurality of storage areas, and an AD control circuit for controlling the drive of the individual components according to an instruction of a CPU. When the analog signals input to the channels are converted into digital signals in sequence, priority is given to AD conversion of the analog signal input to the main channel over AD conversion of the analog signal input to the sub channel.

Analog-digital converting device

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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Brookline, MA, United States of America

Rika Minami