By Thomas Hsu
From National Taiwan University of Science and Technology
(N.T.U.S.T.)
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NEC VCM (Virtual Channel Memory)
1. NEC provides VC-SDRAM solution which is compatible with current
SDRAM technology.
1.1. Pin-to-pin comatible with current SDRAM.
1.2. Interface is compatible with current SDRAM (LVTTL and SSTL)
1.3. BIOS easily recognizes VC SDRAM by using SPD.
2. VCM uses 16 channel (16 row cache)in SDRAM.
Enables higher system performance without any system design
changes.
3. Each channel has 1Kbit SDRAM row cache.
4. Lower read latency.
5. Higher channel hit rate (16 Channels with no page trashing)
6. Concurrent access(Read/PreCharge/Refresh)
7.Higher frequency and DDR are easy to achieve.
8. 30% less power consumption
| Test condition | x4 | x8 | x16 |
-----------------------------+-------+------+--------
64M SDRAM | 100MHz |70mA | 80mA | 130mA|
| CL=2 |
| BL= |
| All bank : active|
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64M VC- |100MHz |45mA | 50mA | 75 mA|
SDRAM | CL=2 |
| BL= |
| All bank :Stanby |
| All channel : active
|
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9. Less thermal problem
10.No cost Premium fro VCM
10.1. Same die size as SDRAM
10.2. High yield rate
10.3. Same package
10.4. Same testing equipment
11. Easy to use VCM for PCB
11.1. No design change with current SDRAM
11.2. Same design rule with current SDRAM
11.3. No extra design effort need
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※ Origin: 楓橋驛站<bbs.cs.nthu.edu.tw> ◆ From: 202.145.217.165