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About Random Access Memory (SRAM and DRAM), if multiple read or write operation take place, many books calculate the average access time of those operations. Given the definition of access time, I think that it is wrong to talk about access time. If multiple operation take place, I think that would be better to talk about average CYCLE TIME, because the cycle time includes the time that the RAM spent to set-up itself after each operation. Could someone tell me if this reasoning is correct? Thank you

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Cycle time is usually a constant value representing the time between any two clock ticks. This also defines how many operations we can do in the cpu per second. This value is mostly constant, except for some special cpu-s that don't use clocks.

But the RAM is a totally different object that takes different time for different requests (depending on how you built it, the number of caches, their size, etc...). So a notion of "average time" here in my opinion is much more meaningful than a notion of average clock cycle time. In addition, since a RAM is a totally different entity, it could operate with an external clock, or using some other mechanism. For the cpu it doesn't matter if it provides the same API. This in some sense, is a sort of abstraction of how the cache really works physically, which makes the "average time" even more useful, as we don't always know exactly how much time a request from the RAM will take.

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  • $\begingroup$ Just a clarification: in my answer I use the term Cycle Time to indicate the cycle time of the memory, that is the time between two subsequent request that the memory can handle. In a document of IBM, the cycle time is defined as follows: "The cycle time is the amount of time required to perform a single read or write operation and reset the internal circuitry so that another operation can begin" $\endgroup$
    – Bender
    Jul 11 at 16:58
  • $\begingroup$ What is the source for this “definition”, especially what year? In 2021, computers use all the tricks you could think of to reduce average time, and it is very unlikely that something like this “cycle time” exists in any meaningful way. $\endgroup$
    – gnasher729
    Aug 10 at 16:43

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