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--- en:multiasm:cs:chapter_3_8 [2025/12/05 08:54] – [Instruction encoding] ktokarz
+++ en:multiasm:cs:chapter_3_8 [2025/12/05 09:59] (current) – [Instruction Execution Process] ktokarz
@@ Line 1: / Line 1: @@
 ===== Instruction Execution Process ======
-As we already mentioned, instructions are executed by the processor in a few steps. You can find in the literature descriptions that there are three, four, or five stages of instruction execution. Everything depends on the level of detail one considers. The three stages description says that there are fetch, decode and execute steps. The four-stage model says that there are fetch, decode, data read and execute steps. The five stages version adds another final step for writing the result back and sometimes reverses the steps of data read and execution.
+As we already mentioned, instructions are executed by the processor in a few steps. You can find in the literature descriptions that there are three, four, or five stages of instruction execution. Everything depends on the level of detail one considers. The three-stage description says that there are fetch, decode and execute steps. The four-stage model says that there are fetch, decode, data read and execute steps. The five-stage version adds another final step for writing the result back and sometimes reverses the steps of data read and execution.
-It is worth remembering that even a simple fetch step can be divided into a set of smaller actions which must be performed by the processor. The real execution of instructions depends on the processor's architecture, implementation and complexity. Considering the five-stage model we can describe the general model of instruction execution:
+It is worth remembering that even a simple fetch step can be divided into a set of smaller actions which must be performed by the processor. The real execution of instructions depends on the processor's architecture, implementation and complexity. Considering the five-stage model, we can describe the general stages of instruction execution:
   - Fetching the instruction:
-    * The processor addresses the instruction by sending the content of the IP register by the address bus.
+    * The processor addresses the instruction by sending the content of the IP register on the address bus.
-    * The processor reads the code of the instruction from program memory by data bus.
+    * The processor reads the code of the instruction from program memory through the data bus.
     * The processor stores the code of the instruction in the instruction register.
     * The processor prepares the IP (possibly increments) to point to the next instruction in a stream.
   - Instruction decoding:
-    * A simple instruction can be interpreted directly by instruction decoder logic.
+    * A simple instruction can be interpreted directly by the instruction decoder logic.
     * More complex instructions are processed in some steps by microcodes.
     * Results are provided to the execution unit.
@@ Line 18: / Line 18: @@
   - Instruction execution:
     * The execution unit performs actions as encoded in the instruction (simple or with microcode).
-    * In modern processors there are more execution units, they can execute different instructions simultaneously.
+    * In modern processors, there are more execution units, and they can execute several instructions simultaneously.
   - Writing back the result:
     * The processor writes the result of calculations into the register or memory.

en/multiasm/cs/chapter_3_8.1764924870.txt.gz · Last modified: 2025/12/05 08:54 by ktokarz