Here are the high points of this chapter. Review these just before you take the exam to brush up on the major topics and help you identify what you need to review.
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Adding RAM to systems improves performance by minimizing disk accesses and by providing a larger workspace.
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Adding cache RAM to systems improves performance for memory-bound operations. However, recent systems incorporate L2 cache in the processor.
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To add RAM to a system, you must know both the CPU type and the type(s) of modules the system needs to determine the number of memory modules needed.
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SDRAM and DDR SDRAM DIMMs are the most common modules used on recent systems and can be added one at a time to normal (single-channel) systems.
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Dual-channel systems require two identical DIMMs.
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Some advanced systems use RAMBUS modules.
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SIMM speeds are rated in nanoseconds (ns).
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SDRAM and Rambus speeds are rated in MHz (PC-133 or 133MHz SDRAM; PC800 or 800MHz Rambus).
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DDR SDRAM speeds are rated in MHz or in throughput (DDR333 [333MHz] or PC2700).
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CAS Latency (CL) values are used when specifying SDRAM and DDR SDRAM. Smaller CL values are faster.
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Exchanging one module at a time is a good way to determine which module has failed in a system.
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Cache memory should be disabled when main memory is tested .