New P2 Silicon Observations

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Comments

  • Right?
    Do not taunt Happy Fun Ball! @opengeekorg ---> Be Excellent To One Another SKYPE = acuity_doug
  • potatohead wrote: »
    Right?

    Not sure, but I was under the impression that it had something to do with byte/long alignment between hub and cog execution.
    In science there is no authority. There is only experiment.
    Life is unpredictable. Eat dessert first.
  • potatoheadpotatohead Posts: 9,915
    edited 2018-11-19 - 21:33:12
    Oh that was in response to cool 6809 stuff.

    Yes, as I remember bytes are the common denominator. With that encoding, there is a quick computation done in COG or HUB, allowing code to run either way.

    Seems odd when looking at other chips. Makes sense on the P2 and the different addressing spaces.

    Can't find the thread on mobile... but, it may be just a shift for the COG, or in VERILOG, taking the upper bits only. It is an add for the HUB.





    Do not taunt Happy Fun Ball! @opengeekorg ---> Be Excellent To One Another SKYPE = acuity_doug
  • __red__ wrote: »
    ... so it is true that the actual **coded instruction** is still encoded in bytes but its assembly analog is written in longs?
    Yes. Physically it is whole 32-bit registers, so it's the byte addressing of code that is hardware emulated by cogexec mode. Probably needs some documenting beyond the forum. Can Google Docs do drawings?

    (and the next location of code that should execute after a JMP is (encoded value/4)-1?
    Not sure how to read that, but PC-relative is with respect to the instruction following the branch. ie: Program counter is already incremented and next instruction is fetched by the time the branch is executing, so the distance to jump is taken from that.

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  • evanhevanh Posts: 8,372
    edited 2018-12-06 - 10:52:11
    Cluso,
    Might have the other piece you were asking for, after having just pondered the addressing modes a little further in another topic - https://forums.parallax.com/discussion/169317/hub-ram-below-400-and-in-rom-area?/p1
    dat
    org
    '+++++++++++++++++++++++++++++++++++++++++   orgf $018
    		loc     ptra, #palette     '   $0005c
    		loc     ptra, #@palette    '   $00178
    		loc     ptra, #palette     '   $00054
    		loc     ptra, #\palette    '   $00018
    		loc     ptra, #\@palette   '   $00060
    
    		mov     ptra, #palette     '   $018
    		mov     ptra, ##palette    '   $00018
    		mov     ptra, ##@palette   '   $00060
    
    orgf  $018
    palette		long    $12345678
    
    

    EDIT: The $178 address, like previous case, is way wrong: https://forums.parallax.com/discussion/comment/1454261/#Comment_1454261

    EDIT2: More learning and clarification here - https://forums.parallax.com/discussion/comment/1457026/#Comment_1457026

    We have the vastness of the internet and yet billions of people decided to spend most of their time within a horribly designed, fake-news emporium of a website that sucks every possible piece of personal information out of you so it can sell it to others. And they see nothing wrong with that.
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