PRELIMINARY DATA SHEET
MOS INTEGRATED CIRCUIT
Direct RambusTM DRAM RIMMTM Module
256M-BYTE (128M-WORD x 16-BIT)
The Direct Rambus RIMM module is a general-purpose high-performance memory module subsystem suitable for
use in a broad range of applications including computer memory, personal computers, workstations, and other
applications where high bandwidth and low latency are required.
MC-4R256CEE6B, 4R256CEE6C modules consists of sixteen 128M Direct Rambus DRAM (Direct RDRAM™)
devices (µPD488448). These are extremely high-speed CMOS DRAMs organized as 8M words by 16 bits. The use
of Rambus Signaling Level (RSL) technology permits 600MHz, 711MHz or 800MHz transfer rates while using
conventional system and board design technologies.
Direct RDRAM devices are capable of sustained data transfers at 1.25 ns per two bytes (10 ns per sixteen bytes).
The architecture of the Direct RDRAM enables the highest sustained bandwidth for multiple, simultaneous,
randomly addressed memory transactions. The separate control and data buses with independent row and column
control yield over 95 % bus efficiency. The Direct RDRAM's 32 banks support up to four simultaneous transactions
• 184 edge connector pads with 1mm pad spacing
• 256 MB Direct RDRAM storage
• Each RDRAM® has 32 banks, for 512 banks total on module
• Gold plated contacts
• RDRAMs use Chip Scale Package (CSP)
• Serial Presence Detect support
• Operates from a 2.5 V supply
• Low power and powerdown self refresh modes
• Separate Row and Column buses for higher efficiency
The information in this document is subject to change without notice. Before using this document, please
confirm that this is the latest version.
Not all devices/types available in every country. Please check with local NEC representative for
availability and additional information.
Document No. M14541EJ1V1DS00 (1st edition)
Date Published November 1999 NS CP (K)
Printed in Japan
The mark 5 shows major revised points.