Graphics Memories for Multimedia

Masataka Sakamoto, Semiconductor & Integrated Circuits Division, Hitachi, Ltd.
Shinji Ishikawa, Semiconductor & Integrated Circuits Division, Hitachi, Ltd.
Yozo Saiki, Electron Tube & Devices Division, Hitachi, Ltd.
Takeshi Kizaki, Semiconductor & Integrated Circuits Division, Hitachi, Ltd.


Graphics performance is very important in the growing multimedia market. The demand for high-speed and low-cost memory for graphics is becoming higher, corresponding with large displays, massive image processing and graphics compression/expansion.

A high bandwidth between the microprocessor unit (MPU) and graphics memory is necessary to do graphics expansion. Video random access memory (VRAM) suits graphics systems because of its multi port organization, but the bandwidth to the MPU is the same as for DRAMs. VRAM is expensive because the die size is bigger than for dynamic RAMs (DRAM).

Hitachi is producing synchronous DRAM and synchronous graphics RAM to meet the market demands of high speed and low price. These products achieve high bandwidth in order to operate at high frequencies by pipe-line and dual bank techniques. In particular, synchronous graphic RAM (SGRAM) drawing performance is higher because of block write and mask write functions.

Frame memory for graphics systems is being produced as well. This product is used in a system which produces digital graphics data from analog graphics data in the multimedia market.

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