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10 Cards in this Set
- Front
- Back
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What is an Operating System? |
> a layer of software > a resource manager > a mechanism for virtualizing hardware resources |
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Role of the Operating System |
> builds the Program Execution Environment > provides a layer of software between user applications and the hardware |
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Applications Directly Accessing Hardware |
+ small performance improvement - not portable - more complex - difficulty running w/ other applications |
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Resource Manager |
> allows programs to share hardware in a fair and efficient way |
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Major Components of Hardware |
> do stuff (CPUs) > store stuff (Program/data) > interact w/ outside world |
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Functions of the CPU |
> executes a sequence of machine instructions > registers - gen. purpose and special purpose - captures instantaneous state of the CPU > can have multiple CPUs or cores |
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Cache |
> faster, smaller storage (cache) > temporarily holds subset of a larger, slower storage area. |
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On Access, First Check... |
cache > if info is in cache, cache hit > if info is not in cache, cache miss, goes to backing store > sometimes copied to make faster |
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Why Does Caching Work? |
> Temporal Locality: A program is likely to access data it has accessed recently > Spatial Locality: A program is likely to access data nearby to what has been accessed recently |
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CPU Functions |
> communicates with devices through device controllers > initiate I/O requests, check I/O status or recover results > interacts with DCs thru read/write functions |
