description
The SMJ55161 multiport-video random-access memory (RAM) is a high-speed, dual-port memory device. It consists of a dynamic RAM (DRAM) module organized as 262 144 words of 16 bits each interfaced to a serial-data register (serial-access memory [SAM]) organized as 256 words of 16 bits each. The SMJ55161 supports three basic types of operation: random access to and from the DRAM, serial access from the serial register, and transfer of data from any row in the DRAM to the serial register. Except during transfer operations, the SMJ55161 can be accessed simultaneously and asynchronously from the DRAM and SAM ports.

• Organization:
   – DRAM: 262 144 by 16 Bits
   – SAM: 256 by 16 Bits
• Dual-Port Accessibility – Simultaneous and Asynchronous Access From the DRAM and SAM Ports
• Data-Transfer Function From the DRAM to the Serial-Data Register
• (4 × 4) × 4 Block-Write Feature for Fast Area-Fill Operations; as Many as Four Memory-Address Locations Written Per Cycle From the 16-Bit On-Chip Color Register
• Write-Per-Bit Feature for Selective Write to Each RAM I/O; Two Write-Per-Bit Modes to Simplify System Design
• Byte-Write Control (CASL, CASU) Provides Flexibility
• Extended Data Output for Faster System Cycle Time
• Enhanced Page-Mode Operation for Faster Access
• CAS-Before-RAS (CBR) and Hidden-Refresh Modes
• Long Refresh Period Every 8 ms (Maximum)
• Up to 45-MHz Uninterrupted Serial-Data Streams
• 256 Selectable Serial-Register Starting Locations
• SE-Controlled Register-Status QSF
• Split-Register-Transfer Read for Simplified Real-Time Register Load
• Programmable Split-Register Stop Point
• 3-State Serial Outputs Allow Easy Multiplexing of Video-Data Streams
• All Inputs/Outputs and Clocks TTL Compatible
• Compatible With JEDEC Standards
• Designed to Work With the Texas Instruments Graphics Family