Are some CPUs implemented in standard cells and are others customized?

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Explaining the question more, I see some die pictures which are implementing a Cortex-M0, with Bluetooth LE and so on, depending on the chip functionality, and are appearing like this (nRF51822):



nRF51822



While on older CPUs I cannot see much digital "fuzzy" logic implementation, like this (AMD386):



AMD386



After googling a bit, it seems that today's ARM implementations are made with standard cells (creating the amorphous shapes on the die). So I can say that the "fuzzy" implementation on the first picture is the Cortex itself.



I understand that all the regular shapes may be memories and all the "hand-drawn" parts are analog. So I wonder, in the past were the analog designers to implement the digital parts under the guide of digital guys who were defining the architecture?



What am I missing?










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  • 2




    Worth pointing out that it's difficult to compare these two dies for a range of reasons: process (AM386 was 800 nm, M0 is probably <100 nm), type (CPU vs micro - memories are very different), generation (1991 vs 2009 - vastly different tooling) etc.
    – awjlogan
    4 hours ago
















up vote
3
down vote

favorite
1












Explaining the question more, I see some die pictures which are implementing a Cortex-M0, with Bluetooth LE and so on, depending on the chip functionality, and are appearing like this (nRF51822):



nRF51822



While on older CPUs I cannot see much digital "fuzzy" logic implementation, like this (AMD386):



AMD386



After googling a bit, it seems that today's ARM implementations are made with standard cells (creating the amorphous shapes on the die). So I can say that the "fuzzy" implementation on the first picture is the Cortex itself.



I understand that all the regular shapes may be memories and all the "hand-drawn" parts are analog. So I wonder, in the past were the analog designers to implement the digital parts under the guide of digital guys who were defining the architecture?



What am I missing?










share|improve this question



















  • 2




    Worth pointing out that it's difficult to compare these two dies for a range of reasons: process (AM386 was 800 nm, M0 is probably <100 nm), type (CPU vs micro - memories are very different), generation (1991 vs 2009 - vastly different tooling) etc.
    – awjlogan
    4 hours ago












up vote
3
down vote

favorite
1









up vote
3
down vote

favorite
1






1





Explaining the question more, I see some die pictures which are implementing a Cortex-M0, with Bluetooth LE and so on, depending on the chip functionality, and are appearing like this (nRF51822):



nRF51822



While on older CPUs I cannot see much digital "fuzzy" logic implementation, like this (AMD386):



AMD386



After googling a bit, it seems that today's ARM implementations are made with standard cells (creating the amorphous shapes on the die). So I can say that the "fuzzy" implementation on the first picture is the Cortex itself.



I understand that all the regular shapes may be memories and all the "hand-drawn" parts are analog. So I wonder, in the past were the analog designers to implement the digital parts under the guide of digital guys who were defining the architecture?



What am I missing?










share|improve this question















Explaining the question more, I see some die pictures which are implementing a Cortex-M0, with Bluetooth LE and so on, depending on the chip functionality, and are appearing like this (nRF51822):



nRF51822



While on older CPUs I cannot see much digital "fuzzy" logic implementation, like this (AMD386):



AMD386



After googling a bit, it seems that today's ARM implementations are made with standard cells (creating the amorphous shapes on the die). So I can say that the "fuzzy" implementation on the first picture is the Cortex itself.



I understand that all the regular shapes may be memories and all the "hand-drawn" parts are analog. So I wonder, in the past were the analog designers to implement the digital parts under the guide of digital guys who were defining the architecture?



What am I missing?







arm cpu semiconductors die






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edited 21 mins ago









Peter Mortensen

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1,56231422










asked 5 hours ago









thexeno

570312




570312







  • 2




    Worth pointing out that it's difficult to compare these two dies for a range of reasons: process (AM386 was 800 nm, M0 is probably <100 nm), type (CPU vs micro - memories are very different), generation (1991 vs 2009 - vastly different tooling) etc.
    – awjlogan
    4 hours ago












  • 2




    Worth pointing out that it's difficult to compare these two dies for a range of reasons: process (AM386 was 800 nm, M0 is probably <100 nm), type (CPU vs micro - memories are very different), generation (1991 vs 2009 - vastly different tooling) etc.
    – awjlogan
    4 hours ago







2




2




Worth pointing out that it's difficult to compare these two dies for a range of reasons: process (AM386 was 800 nm, M0 is probably <100 nm), type (CPU vs micro - memories are very different), generation (1991 vs 2009 - vastly different tooling) etc.
– awjlogan
4 hours ago




Worth pointing out that it's difficult to compare these two dies for a range of reasons: process (AM386 was 800 nm, M0 is probably <100 nm), type (CPU vs micro - memories are very different), generation (1991 vs 2009 - vastly different tooling) etc.
– awjlogan
4 hours ago










1 Answer
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No, analog IC designers were not creating microprocessors under the direction of digital architects. It's more correct to say that digital integrated circuit designers needed to know quite a bit about how the transistors actually behaved.



The choice of whether a particular part of a digital IC will be crafted using standard cells or hand-drawn circuits is simply a matter of economics. For dense, highly-repetitive structures like memories (cache, microcode ROM, register file) it made sense to invest time in handcrafting the few basic cells that would be tiled together...the result was much smaller and faster than an equivalent circuit made from standard cells.



Blocks of "random logic" such as state machines and small counters were created using standard cells and CAD tools. Creating hand-crafted layouts for these blocks would have taken an enormous amount of time and provided little benefit. Instead, people worked to make the CAD tools and cell libraries better.






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    1 Answer
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    1 Answer
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    up vote
    9
    down vote













    No, analog IC designers were not creating microprocessors under the direction of digital architects. It's more correct to say that digital integrated circuit designers needed to know quite a bit about how the transistors actually behaved.



    The choice of whether a particular part of a digital IC will be crafted using standard cells or hand-drawn circuits is simply a matter of economics. For dense, highly-repetitive structures like memories (cache, microcode ROM, register file) it made sense to invest time in handcrafting the few basic cells that would be tiled together...the result was much smaller and faster than an equivalent circuit made from standard cells.



    Blocks of "random logic" such as state machines and small counters were created using standard cells and CAD tools. Creating hand-crafted layouts for these blocks would have taken an enormous amount of time and provided little benefit. Instead, people worked to make the CAD tools and cell libraries better.






    share|improve this answer
























      up vote
      9
      down vote













      No, analog IC designers were not creating microprocessors under the direction of digital architects. It's more correct to say that digital integrated circuit designers needed to know quite a bit about how the transistors actually behaved.



      The choice of whether a particular part of a digital IC will be crafted using standard cells or hand-drawn circuits is simply a matter of economics. For dense, highly-repetitive structures like memories (cache, microcode ROM, register file) it made sense to invest time in handcrafting the few basic cells that would be tiled together...the result was much smaller and faster than an equivalent circuit made from standard cells.



      Blocks of "random logic" such as state machines and small counters were created using standard cells and CAD tools. Creating hand-crafted layouts for these blocks would have taken an enormous amount of time and provided little benefit. Instead, people worked to make the CAD tools and cell libraries better.






      share|improve this answer






















        up vote
        9
        down vote










        up vote
        9
        down vote









        No, analog IC designers were not creating microprocessors under the direction of digital architects. It's more correct to say that digital integrated circuit designers needed to know quite a bit about how the transistors actually behaved.



        The choice of whether a particular part of a digital IC will be crafted using standard cells or hand-drawn circuits is simply a matter of economics. For dense, highly-repetitive structures like memories (cache, microcode ROM, register file) it made sense to invest time in handcrafting the few basic cells that would be tiled together...the result was much smaller and faster than an equivalent circuit made from standard cells.



        Blocks of "random logic" such as state machines and small counters were created using standard cells and CAD tools. Creating hand-crafted layouts for these blocks would have taken an enormous amount of time and provided little benefit. Instead, people worked to make the CAD tools and cell libraries better.






        share|improve this answer












        No, analog IC designers were not creating microprocessors under the direction of digital architects. It's more correct to say that digital integrated circuit designers needed to know quite a bit about how the transistors actually behaved.



        The choice of whether a particular part of a digital IC will be crafted using standard cells or hand-drawn circuits is simply a matter of economics. For dense, highly-repetitive structures like memories (cache, microcode ROM, register file) it made sense to invest time in handcrafting the few basic cells that would be tiled together...the result was much smaller and faster than an equivalent circuit made from standard cells.



        Blocks of "random logic" such as state machines and small counters were created using standard cells and CAD tools. Creating hand-crafted layouts for these blocks would have taken an enormous amount of time and provided little benefit. Instead, people worked to make the CAD tools and cell libraries better.







        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered 5 hours ago









        Elliot Alderson

        2,9681412




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