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Scratch Build – In Progress Z80 computer project

Discussion in 'Project Logs' started by Kipman725, 22 Oct 2007.

  1. toru173

    toru173 What's a Dremel?

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    Is it necesary to use eeprom? Maxim sells (samples!) some very nice 2Mx8bit battery backed sram in a simple pdip package, with the onboard battery rated to 5 years. You'd be able to leave the "rom" in lower ram (say) and just erase everything above it on boot up. If you're worried about the 5 year limit you could always have a secondary trickle battery that only kicks in when there's no other power and only powers the ram. You'll probably need such a battery if you're going to include an RTC anyway, which might be handy.
     
  2. ClearCaseMan

    ClearCaseMan Acrylic GOD

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  3. 12modderz

    12modderz L33T еÐ3!

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    Funniest thing I've heard today! :thumb:

    Confusing and Brilliant Project, will follow it up. Wonder if it could do 5mhz???? LOL
     
  4. mattthegamer463

    mattthegamer463 What's a Dremel?

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    Not without LN2.

    Do you have a purpose for this project? With something like this you would be tailoring the device from the beginning to perform a certain function.
     
  5. Kipman725

    Kipman725 When did I get a custom title!?!

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    hello everyone I am not inactive on this project just to tell you I have decided to make things LESS confusing and am currently engaged in the design of the memory controll logic and some rediculasly complex sequential logic for my I2C EEPROM interface and more impotantly have been righting it all up (been tapping away at the keyboard for 5hrs straight). 5MHz will almost certiantly be posible from this chip and you can get versions of the Z80 CPU rated at 120MHz. Curently the main bottle neak is not the CPU but fetching instructions form the EEPROM as it's only running at 400kHz and it takes (I havent worked it all out yet) but about 30clock cycles to get an instruction from it. During which the cpu is in a wait state and not able to do anything!
    Anyway my long long term plan is for it to be able to play a version of "is it a fish?"

    As for unique features differentiating my Z80 project from others, I am going to use an SX or simlar to read from an area of shared ram between it and the CPU containing the display data and run it asycronus to the CPU. Therfore when not changing what is on the screen at the same time as the SX is trying to read the memory to genrate the TV picture the CPU will not be in a wait state and therfore will be faster than other z80 based systems at the same speed. Even having a display is... far in the future though.

    anyway boolean algebra to do :)
     

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