Where does the Z80 processor start executing from?How did the Z80 instruction set differ from the 8080?Why does the Z80 have a half-carry bit?How fast is memcpy on the Z80?z80 crashes after executing some instructionsWhy does the Z80 include the RLD and RRD instructions?Why is the Z80's supply pin in the middle of the data pins?Why did TI-8x calculator series use the Z80 processor?Role of the Z80 co-processor in GBA gamesHow do I Interface a PS/2 Keyboard without Modern Techniques?What does ld a,(hl) do in this piece of Z80 ASM code, and why is HL incremented?

Does "every" first-order theory have a finitely axiomatizable conservative extension?

Why escape if the_content isnt?

What is the best translation for "slot" in the context of multiplayer video games?

How can we prove that any integral in the set of non-elementary integrals cannot be expressed in the form of elementary functions?

Failed to fetch jessie backports repository

Trouble understanding the speech of overseas colleagues

Do sorcerers' subtle spells require a skill check to be unseen?

How can I kill an app using Terminal?

How did Arya survive the stabbing?

How to Reset Passwords on Multiple Websites Easily?

As a short term trader, do I personally have to keep track of every wash sale for tax purposes?

How long to clear the 'suck zone' of a turbofan after start is initiated?

How to be diplomatic in refusing to write code that breaches the privacy of our users

Fastening aluminum fascia to wooden subfascia

How do scammers retract money, while you can’t?

Why didn't Theresa May consult with Parliament before negotiating a deal with the EU?

Anatomically Correct Strange Women In Ponds Distributing Swords

Escape a backup date in a file name

Large drywall patch supports

Class Action - which options I have?

Where does the Z80 processor start executing from?

Why, precisely, is argon used in neutrino experiments?

What is the opposite of 'gravitas'?

Balance Issues for a Custom Sorcerer Variant



Where does the Z80 processor start executing from?


How did the Z80 instruction set differ from the 8080?Why does the Z80 have a half-carry bit?How fast is memcpy on the Z80?z80 crashes after executing some instructionsWhy does the Z80 include the RLD and RRD instructions?Why is the Z80's supply pin in the middle of the data pins?Why did TI-8x calculator series use the Z80 processor?Role of the Z80 co-processor in GBA gamesHow do I Interface a PS/2 Keyboard without Modern Techniques?What does ld a,(hl) do in this piece of Z80 ASM code, and why is HL incremented?













9















Strangely I can't find this information anywhere online -- I've thoroughly looked at the datasheet, and I've searched things like "Z80 program counter initial value" -- but I can't find anything!



My question is simply: when the Z80 just turns on, what value does the program counter take? (i.e., what instruction does it start executing from?)



Logically, I'd assume it initialises to 0, but I want to be sure of this.










share|improve this question







New contributor




Jacob Garby is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
























    9















    Strangely I can't find this information anywhere online -- I've thoroughly looked at the datasheet, and I've searched things like "Z80 program counter initial value" -- but I can't find anything!



    My question is simply: when the Z80 just turns on, what value does the program counter take? (i.e., what instruction does it start executing from?)



    Logically, I'd assume it initialises to 0, but I want to be sure of this.










    share|improve this question







    New contributor




    Jacob Garby is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.






















      9












      9








      9








      Strangely I can't find this information anywhere online -- I've thoroughly looked at the datasheet, and I've searched things like "Z80 program counter initial value" -- but I can't find anything!



      My question is simply: when the Z80 just turns on, what value does the program counter take? (i.e., what instruction does it start executing from?)



      Logically, I'd assume it initialises to 0, but I want to be sure of this.










      share|improve this question







      New contributor




      Jacob Garby is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.












      Strangely I can't find this information anywhere online -- I've thoroughly looked at the datasheet, and I've searched things like "Z80 program counter initial value" -- but I can't find anything!



      My question is simply: when the Z80 just turns on, what value does the program counter take? (i.e., what instruction does it start executing from?)



      Logically, I'd assume it initialises to 0, but I want to be sure of this.







      z80






      share|improve this question







      New contributor




      Jacob Garby is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.











      share|improve this question







      New contributor




      Jacob Garby is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.









      share|improve this question




      share|improve this question






      New contributor




      Jacob Garby is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.









      asked 5 hours ago









      Jacob GarbyJacob Garby

      1483




      1483




      New contributor




      Jacob Garby is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.





      New contributor





      Jacob Garby is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.






      Jacob Garby is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.




















          1 Answer
          1






          active

          oldest

          votes


















          9














          Yes, it's zero - like the 8080 it descends from.



          Excerpt from Zilog's March 1978 Product Specification (datasheet), page 2, Pin Description, here the /RESET signal (emphasis mine):




          Input, active low. RESET initializes the CPU as follows:
          reset interrupt enable flip-flop, clear PC and registers
          I and R and set interrupt to 8080A mode.




          Similar the description in the 1977 Z80 Technical Manual (03-0029-01) on page 9.






          share|improve this answer

























          • Thanks! I actually didn't know that the 8080 started at zero either, but it makes complete sense.

            – Jacob Garby
            5 hours ago











          • Does anything not start at zero?

            – dashnick
            2 hours ago






          • 7





            @dashnick Many don't just start, but take a vector form a predefined location like 6500 and 6800 start at the vector residing at FFFE/FF, 68k takes the initial PC from Vector 1 (address 4..7). Other do start form some address where the IOC locates a loader record, and so on. Starting from Zero is only one of many ways.

            – Raffzahn
            1 hour ago






          • 4





            Intels 8086 employs an interesting combination by starting a offset zero, like 8080/Z80, but in segment FFFF, thus at absolute address FFFF0.

            – Raffzahn
            1 hour ago










          Your Answer








          StackExchange.ready(function()
          var channelOptions =
          tags: "".split(" "),
          id: "648"
          ;
          initTagRenderer("".split(" "), "".split(" "), channelOptions);

          StackExchange.using("externalEditor", function()
          // Have to fire editor after snippets, if snippets enabled
          if (StackExchange.settings.snippets.snippetsEnabled)
          StackExchange.using("snippets", function()
          createEditor();
          );

          else
          createEditor();

          );

          function createEditor()
          StackExchange.prepareEditor(
          heartbeatType: 'answer',
          autoActivateHeartbeat: false,
          convertImagesToLinks: false,
          noModals: true,
          showLowRepImageUploadWarning: true,
          reputationToPostImages: null,
          bindNavPrevention: true,
          postfix: "",
          imageUploader:
          brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
          contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
          allowUrls: true
          ,
          noCode: true, onDemand: true,
          discardSelector: ".discard-answer"
          ,immediatelyShowMarkdownHelp:true
          );



          );






          Jacob Garby is a new contributor. Be nice, and check out our Code of Conduct.









          draft saved

          draft discarded


















          StackExchange.ready(
          function ()
          StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fretrocomputing.stackexchange.com%2fquestions%2f9448%2fwhere-does-the-z80-processor-start-executing-from%23new-answer', 'question_page');

          );

          Post as a guest















          Required, but never shown

























          1 Answer
          1






          active

          oldest

          votes








          1 Answer
          1






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes









          9














          Yes, it's zero - like the 8080 it descends from.



          Excerpt from Zilog's March 1978 Product Specification (datasheet), page 2, Pin Description, here the /RESET signal (emphasis mine):




          Input, active low. RESET initializes the CPU as follows:
          reset interrupt enable flip-flop, clear PC and registers
          I and R and set interrupt to 8080A mode.




          Similar the description in the 1977 Z80 Technical Manual (03-0029-01) on page 9.






          share|improve this answer

























          • Thanks! I actually didn't know that the 8080 started at zero either, but it makes complete sense.

            – Jacob Garby
            5 hours ago











          • Does anything not start at zero?

            – dashnick
            2 hours ago






          • 7





            @dashnick Many don't just start, but take a vector form a predefined location like 6500 and 6800 start at the vector residing at FFFE/FF, 68k takes the initial PC from Vector 1 (address 4..7). Other do start form some address where the IOC locates a loader record, and so on. Starting from Zero is only one of many ways.

            – Raffzahn
            1 hour ago






          • 4





            Intels 8086 employs an interesting combination by starting a offset zero, like 8080/Z80, but in segment FFFF, thus at absolute address FFFF0.

            – Raffzahn
            1 hour ago















          9














          Yes, it's zero - like the 8080 it descends from.



          Excerpt from Zilog's March 1978 Product Specification (datasheet), page 2, Pin Description, here the /RESET signal (emphasis mine):




          Input, active low. RESET initializes the CPU as follows:
          reset interrupt enable flip-flop, clear PC and registers
          I and R and set interrupt to 8080A mode.




          Similar the description in the 1977 Z80 Technical Manual (03-0029-01) on page 9.






          share|improve this answer

























          • Thanks! I actually didn't know that the 8080 started at zero either, but it makes complete sense.

            – Jacob Garby
            5 hours ago











          • Does anything not start at zero?

            – dashnick
            2 hours ago






          • 7





            @dashnick Many don't just start, but take a vector form a predefined location like 6500 and 6800 start at the vector residing at FFFE/FF, 68k takes the initial PC from Vector 1 (address 4..7). Other do start form some address where the IOC locates a loader record, and so on. Starting from Zero is only one of many ways.

            – Raffzahn
            1 hour ago






          • 4





            Intels 8086 employs an interesting combination by starting a offset zero, like 8080/Z80, but in segment FFFF, thus at absolute address FFFF0.

            – Raffzahn
            1 hour ago













          9












          9








          9







          Yes, it's zero - like the 8080 it descends from.



          Excerpt from Zilog's March 1978 Product Specification (datasheet), page 2, Pin Description, here the /RESET signal (emphasis mine):




          Input, active low. RESET initializes the CPU as follows:
          reset interrupt enable flip-flop, clear PC and registers
          I and R and set interrupt to 8080A mode.




          Similar the description in the 1977 Z80 Technical Manual (03-0029-01) on page 9.






          share|improve this answer















          Yes, it's zero - like the 8080 it descends from.



          Excerpt from Zilog's March 1978 Product Specification (datasheet), page 2, Pin Description, here the /RESET signal (emphasis mine):




          Input, active low. RESET initializes the CPU as follows:
          reset interrupt enable flip-flop, clear PC and registers
          I and R and set interrupt to 8080A mode.




          Similar the description in the 1977 Z80 Technical Manual (03-0029-01) on page 9.







          share|improve this answer














          share|improve this answer



          share|improve this answer








          edited 4 hours ago









          George Phillips

          3,5211522




          3,5211522










          answered 5 hours ago









          RaffzahnRaffzahn

          54k6132218




          54k6132218












          • Thanks! I actually didn't know that the 8080 started at zero either, but it makes complete sense.

            – Jacob Garby
            5 hours ago











          • Does anything not start at zero?

            – dashnick
            2 hours ago






          • 7





            @dashnick Many don't just start, but take a vector form a predefined location like 6500 and 6800 start at the vector residing at FFFE/FF, 68k takes the initial PC from Vector 1 (address 4..7). Other do start form some address where the IOC locates a loader record, and so on. Starting from Zero is only one of many ways.

            – Raffzahn
            1 hour ago






          • 4





            Intels 8086 employs an interesting combination by starting a offset zero, like 8080/Z80, but in segment FFFF, thus at absolute address FFFF0.

            – Raffzahn
            1 hour ago

















          • Thanks! I actually didn't know that the 8080 started at zero either, but it makes complete sense.

            – Jacob Garby
            5 hours ago











          • Does anything not start at zero?

            – dashnick
            2 hours ago






          • 7





            @dashnick Many don't just start, but take a vector form a predefined location like 6500 and 6800 start at the vector residing at FFFE/FF, 68k takes the initial PC from Vector 1 (address 4..7). Other do start form some address where the IOC locates a loader record, and so on. Starting from Zero is only one of many ways.

            – Raffzahn
            1 hour ago






          • 4





            Intels 8086 employs an interesting combination by starting a offset zero, like 8080/Z80, but in segment FFFF, thus at absolute address FFFF0.

            – Raffzahn
            1 hour ago
















          Thanks! I actually didn't know that the 8080 started at zero either, but it makes complete sense.

          – Jacob Garby
          5 hours ago





          Thanks! I actually didn't know that the 8080 started at zero either, but it makes complete sense.

          – Jacob Garby
          5 hours ago













          Does anything not start at zero?

          – dashnick
          2 hours ago





          Does anything not start at zero?

          – dashnick
          2 hours ago




          7




          7





          @dashnick Many don't just start, but take a vector form a predefined location like 6500 and 6800 start at the vector residing at FFFE/FF, 68k takes the initial PC from Vector 1 (address 4..7). Other do start form some address where the IOC locates a loader record, and so on. Starting from Zero is only one of many ways.

          – Raffzahn
          1 hour ago





          @dashnick Many don't just start, but take a vector form a predefined location like 6500 and 6800 start at the vector residing at FFFE/FF, 68k takes the initial PC from Vector 1 (address 4..7). Other do start form some address where the IOC locates a loader record, and so on. Starting from Zero is only one of many ways.

          – Raffzahn
          1 hour ago




          4




          4





          Intels 8086 employs an interesting combination by starting a offset zero, like 8080/Z80, but in segment FFFF, thus at absolute address FFFF0.

          – Raffzahn
          1 hour ago





          Intels 8086 employs an interesting combination by starting a offset zero, like 8080/Z80, but in segment FFFF, thus at absolute address FFFF0.

          – Raffzahn
          1 hour ago










          Jacob Garby is a new contributor. Be nice, and check out our Code of Conduct.









          draft saved

          draft discarded


















          Jacob Garby is a new contributor. Be nice, and check out our Code of Conduct.












          Jacob Garby is a new contributor. Be nice, and check out our Code of Conduct.











          Jacob Garby is a new contributor. Be nice, and check out our Code of Conduct.














          Thanks for contributing an answer to Retrocomputing Stack Exchange!


          • Please be sure to answer the question. Provide details and share your research!

          But avoid


          • Asking for help, clarification, or responding to other answers.

          • Making statements based on opinion; back them up with references or personal experience.

          To learn more, see our tips on writing great answers.




          draft saved


          draft discarded














          StackExchange.ready(
          function ()
          StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fretrocomputing.stackexchange.com%2fquestions%2f9448%2fwhere-does-the-z80-processor-start-executing-from%23new-answer', 'question_page');

          );

          Post as a guest















          Required, but never shown





















































          Required, but never shown














          Required, but never shown












          Required, but never shown







          Required, but never shown

































          Required, but never shown














          Required, but never shown












          Required, but never shown







          Required, but never shown







          Popular posts from this blog

          名間水力發電廠 目录 沿革 設施 鄰近設施 註釋 外部連結 导航菜单23°50′10″N 120°42′41″E / 23.83611°N 120.71139°E / 23.83611; 120.7113923°50′10″N 120°42′41″E / 23.83611°N 120.71139°E / 23.83611; 120.71139計畫概要原始内容臺灣第一座BOT 模式開發的水力發電廠-名間水力電廠名間水力發電廠 水利署首件BOT案原始内容《小檔案》名間電廠 首座BOT水力發電廠原始内容名間電廠BOT - 經濟部水利署中區水資源局

          Prove that NP is closed under karp reduction?Space(n) not closed under Karp reductions - what about NTime(n)?Class P is closed under rotation?Prove or disprove that $NL$ is closed under polynomial many-one reductions$mathbfNC_2$ is closed under log-space reductionOn Karp reductionwhen can I know if a class (complexity) is closed under reduction (cook/karp)Check if class $PSPACE$ is closed under polyonomially space reductionIs NPSPACE also closed under polynomial-time reduction and under log-space reduction?Prove PSPACE is closed under complement?Prove PSPACE is closed under union?

          Is my guitar’s action too high? Announcing the arrival of Valued Associate #679: Cesar Manara Planned maintenance scheduled April 23, 2019 at 23:30 UTC (7:30pm US/Eastern)Strings too stiff on a recently purchased acoustic guitar | Cort AD880CEIs the action of my guitar really high?Μy little finger is too weak to play guitarWith guitar, how long should I give my fingers to strengthen / callous?When playing a fret the guitar sounds mutedPlaying (Barre) chords up the guitar neckI think my guitar strings are wound too tight and I can't play barre chordsF barre chord on an SG guitarHow to find to the right strings of a barre chord by feel?High action on higher fret on my steel acoustic guitar