The [[µOP cache]] used in Zen is not a [[trace cache]] and much closely resembles the one used by Intel in their microarchitectures since {{intel|Sandy Bridge|l=arch}}. The µOP cache is an independent unit not part of the [[L1I$]] and is not a necessarily a subset of the L1I cache either; I.e., there are instances where there could be a hit in the µOP cache but a miss in the L1$. This happens when an instruction that got stored in the µOP cache gets evicted from L1. During the fetch stage probing must be done from both paths. Zen has a specific unit called 'Micro-Tags' which does the probing and determines whether the instruction should be accessed from the µOP cache or from the L1I$. The µOP cache itself has a dedicated $tags for accessing those µOPs.

The [[µOP cache]] used in Zen is not a [[trace cache]] and much closely resembles the one used by Intel in their microarchitectures since {{intel|Sandy Bridge|l=arch}}. The µOP cache is an independent unit not part of the [[L1I$]] and is not a necessarily a subset of the L1I cache either; I.e., there are instances where there could be a hit in the µOP cache but a miss in the L1$. This happens when an instruction that got stored in the µOP cache gets evicted from L1. During the fetch stage probing must be done from both paths. Zen has a specific unit called 'Micro-Tags' which does the probing and determines whether the instruction should be accessed from the µOP cache or from the L1I$. The µOP cache itself has a dedicated $tags for accessing those µOPs.

[[File:amd fastpath single-double (zen).svg|right|450px]]

[[File:amd fastpath single-double (zen).svg|right|450px]]

Having to execute [[x86]], there are instructions that actually include multiple operations. Some of those operations cannot be realized efficiently in an OoOE design and therefore must be converted into simpler operations. In the front-end, complex x86 instructions are broken down into simpler fixed-length operations called [[macro-operations]] or MOPs (sometimes also called complex OPs or COPs). Those are often mistaken for being "[[RISC]]ish" in nature but they retain their CISC characteristics. MOPS can perform both an arithmetic operation and memory operation (e.g. you can read, modify, and write in a single MOP). MOPs can be further cracked into smaller simpler single fixed length operation called [[micro-operations]] (µOPs). µOPs are a fixed length operation that performs just a single operation (i.e., only a single load, store, or an arithmetic). Traditionally AMD used to distinguish between the two ops, however with Zen AMD simply refers to everything as µOPs although internally they are still two separate concepts.

Having to execute [[x86]], there are instructions that actually include multiple operations. Some of those operations cannot be realized efficiently in an OoOE design and therefore must be converted into simpler operations. In the front-end, complex x86 instructions are broken down into simpler fixed-length operations called [[macro-operations]] or MOPs (sometimes also called complex OPs or COPs). Those are often mistaken for being "[[RISC]]ish" in nature but they retain their CISC characteristics. MOPS can perform both an arithmetic operation and memory operation (e.g. you can read, modify, and write in a single MOP). MOPs can be further cracked into smaller simpler single fixed length operation called [[micro-operations]] (µOPs). µOPs are a fixed length operation that performs just a single operation (i.e., only a single load, store, or an arithmetic). Traditionally AMD used to distinguish between the two ops, however with Zen AMD simply refers to everything as µOPs although internally they are still two separate concepts.