HM538123B Datasheet, PDF (1/46 Pages) Hitachi Semiconductor – 1 M VRAM (128-kword x 8-bit)

HM538123B Series
1 M VRAM (128-kword × 8-bit)
ADE-203-231D (Z)
Rev. 4.0
Nov. 1997
Description
The HM538123B is a 1-Mbit multiport video RAM equipped with a 128-kword × 8-bit dynamic RAM and a
256-word × 8-bit SAM (serial access memory). Its RAM and SAM operate independently and
asynchronously. It can transfer data between RAM and SAM. In addition, it has two modes to realize fast
writing in RAM. Block write and flash write modes clear the data of 4-word × 8-bit and the data of one row
(256-word × 8-bit) respectively in one cycle of RAM. And the HM538123B makes split transfer cycle
possible by dividing SAM into two split buffers equipped with 128-word × 8-bit each. This cycle can
transfer data to SAM which is not active, and enables a continuous serial access.
Features
• Multiport organization
Asynchronous and simultaneous operation of RAM and SAM capability
 RAM: 128-kword × 8-bit and
 SAM: 256-word × 8-bit
• Access time
 RAM: 60 ns/70 ns/80 ns/100 ns max
 SAM: 20 ns/22 ns/25 ns/25 ns max
• Cycle time
 RAM: 125 ns/135 ns/150 ns/180 ns min
 SAM: 25 ns/25 ns/30 ns/30 ns min
• Low power
 Active RAM: 413 mW max
SAM: 275 mW max
 Standby 38.5 mW max
• High-speed page mode capability
• Mask write mode capability
• Bidirectional data transfer cycle between RAM and SAM capability
• Split transfer cycle capability
• Block write mode capability
• Flash write mode capability