33 lines
1.4 KiB
Markdown
33 lines
1.4 KiB
Markdown
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---
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title: Role_of_memory_in_computation
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tags: [memory]
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created: Friday, July 12, 2024
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---
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# The role of memory in computation
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The following steps outline the way in which memory interacts with the processor
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during computational cycles, once the [bootstrapping](Boot_process.md) process
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has completed and the OS kernel is itself loaded into memory.
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1. A file is loaded from the harddisk into memory.
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2. The instruction at the first address is sent to the CPU, travelling accross
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the data bus part of the [system bus](Bus.md).
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3. The CPU processes this instruction and then sends a request accross the
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address bus part of the system bus for the next instruction to the memory
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controller within the [chipset](Chipset_and_controllers.md).
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4. The chipset finds where this instruction is stored within the
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[DRAM](Memory.md#dram) and issues a request to have it read out and send to
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the CPU over the data bus.
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> This is a simplified account; it is not the case that only single requests are
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> passed back and forth. This would be inefficient and time-wasting. The kernel
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> sends to the CPU not just the first instruction in the requested file but also
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> a number of instructions that immediately follow it.
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Every part of the above process - the journey accross the bus, the lookup in the
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controller, the operations on the DRAM, the journey back accross the bus - takes
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multiple CPU clock cycles.
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