Is there exist any processor or controller that works on more than one voltage levels ?

Discussion in 'Embedded Systems and Microcontrollers' started by Abhinav Himanshu, Feb 24, 2016.

  1. Abhinav Himanshu

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    Feb 18, 2016
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    Just started a course on digital systems , and got a query that computers that we normally use are based on binary system , that understand only highs and lows (two voltage levels). So what if we design a controller that can understand more than two voltage levels say octal computer. Is there anything like that ? is it even possible ?
     
  2. Papabravo

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    Feb 24, 2006
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    Sure. The Intel x86 parts and the ARM parts all have multiple voltage levels. Just have a look at the datasheets. Typical levels you might find are:
    1. +5VDC
    2. +3.3VDC
    3. +2.7VDC
    4. +1.8VDV
    5. +0.8VDC
    The higher voltages are used for interface to the I/O, and the lower voltages are used for the processor core.

    EDIT: Sorry, while the above is true it does not answer the question. In communications is where multiple voltage level signaling is used. In terms of core logic for a processor there are almost no examples of multi-level logic. What is actually happening is voltage translation to lower levels as you approach the processor core. This is done primarily for power dissipation considerations.
     
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  3. ErnieM

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    While there may be some lab version of a non binary computer they just don't exist as a commercial device.

    However, analog computers were once common to solve some specific or more general calculations. Basically they emulated an equation, they did not do anything like a modern computer (or even a cell phone) does.
     
  4. Papabravo

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    The IEEE standard 802.4 defines a multilevel logic scheme using three levels. In our work we referred to the levels as {0, 2, 4}, where 0 and 4 corresponded to logic levels 0 and 1, while 2 was used as the non-data symbol. The non-data symbol was used to define begin and end frame delimiters, eg. 220220 was a begin delimiter, and 224224 was an end delimiter. There was also Silence and pad-idle.
     
  5. crutschow

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    Mar 14, 2008
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    There have been logic system with more then 2 levels proposed, but the added complexity of the circuits to distinguish between multiple voltage levels meant it didn't really save silicon real estate on an IC to do a given function (which is the primary consideration), so it never became a practical approach to doing digital logic.
     
  6. MrChips

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  7. GetDeviceInfo

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    if you look at nature around us, you may see that digital is man's doing. it's our first go and primitive, and given enough time we'll advance beyond the constraints of 1 and 0s. The possibilities are infinite.
     
  8. ian field

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    Oct 27, 2012
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    AFAICR: some of the early P-MOS devices had multiple rails, including negative ones - it was certainly the case with dynamic RAM.

    In about the past decade or so; manufacturers have been striving for the lowest possible core voltage - it has some similarities to op-amp slew rate, if you reduce how much the voltage has to swing - it can swing faster.

    There are various MCUs designed specifically for driving various displays directly - no shortage of MCUs with pins dedicated to direct drive of LCD panels, there are (or were) MCUs that could drive VFD panels, there may even have been one or two for Nixie displays.
     
  9. crutschow

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    It would seem you haven't followed you own advice and taken a close look at nature around you. ;)
    Digital is not just man's doing, nature is 2-level digital also.
    The nerves in your body transmit signals using a pulse frequency modulation scheme.
    The number of nerve impulses per second determines the intensity of the nerve signal being sent, which typically ranges from 1pps for a minimum signal to 300-400pps for a maximum signal.

    Of course the signal information itself is analog since the frequency has no fixed steps but can vary smoothly between its limits. In that respect it differs from binary logic.
    Other digital modulation schemes like PWM or PPM can also carry the information in non-discrete analog form.
     
  10. John P

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    You can go all the way back to Alan Turing's theoretical work, before electronic computers existed, and see how he based his ideas on 1's and 0's, not fractions. Maybe you could say that was easiest for his purposes, but it's been found to be the easiest way to do computing in the real world too.
     
  11. nsaspook

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    We've already advanced beyond the constraints of 1 and 0s logic states in quantum computing.

    We can design two-state QM systems with a superposition of logic states (qubits).
    https://en.wikipedia.org/wiki/Quantum_gate
     
  12. jpanhalt

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    Jan 18, 2008
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    @crutschow
    Technically you are right. But our brains act on at least three levels: yes, no, and don't know.

    Very early in my career, I introduced that same principle to what had previously been a binary method for bacterial identification [see: API (http://www.biomerieux-usa.com/clinical/api) for an example and other systems of that time, circa 1970's]. I called the system "CARP" (Computer Aided Replica Plating). It worked well and was still in use, relatively unchanged for more than 30 years after it was introduced. While not a completely accurate analogy, a 3-level system is well known. Namely, on, off, and high impedance. This is not my area of expertise, but I am not aware of any 4-level systems.

    Edit: I forgot to add that we used ordinary 2-state logic to attain our goal.

    John
     
    Last edited: Feb 24, 2016
  13. ian field

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    Apparently the higher capacity USB flash drives use multiple logic levels to stuff more data into the physical bits.

    They wear out quicker too.
     
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  14. jpanhalt

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    @ian field
    I did not know that and have just recently gotten into EEPROM reading and writing. Do you have any links that simply explain how such devices are used in a binary system? In particular, does the sender see any difference?

    John
     
  15. WBahn

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    Intel used multi-level ROM (2-bits per cell) as far back as 1980 in the 8087 math coprocessor.

    Currently there 3-bit/cell and 4-bit/cel devices out there (Flash/SSD).

    But multi-bit storage per cell is a very different thing than multi-level processing. I'm not aware of any actual digital processing that is done on anything other than binary.
     
  16. WBahn

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    This all happens inside the chip. You access the data in much larger chunks (such as a sector). Furthermore, on most modern devices you don't have any control over where on the device the data is physically stored, only logically. This allows the device to mark blocks as being bad and to remap that block logically to another block of memory. Similarly, the error-correcting goes on behind the scenes. On most devices you probably could not get the raw, corrupted data off the chip even if you wanted to (without physically going in and doing a destructive read).
     
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  17. crutschow

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    Perhaps at the macro (computer) level, but not at the neuron (gate) level.
    There it's just impulses of varying frequency or (perhaps) no pulses.
     
  18. GetDeviceInfo

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    so is that not the same as sound propagation, or is it truly digitized?
     
  19. crutschow

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    Sound propagation is a series of pressure waves in a mechanical medium (gas or solid) whose amplitude represents the signal amplitude.
    Neural impulses are a series of electrical (digitized) pulses that travel down nerve fibers whose frequency (not amplitude) is the encoded signal amplitude (for example, the more pulse per second down a pain nerve, the more pain you feel).
    They are not at all alike.
     
  20. dannyf

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    Sep 13, 2015
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    There are. 4 or 8 state algorithms are not uncommon.

    Some chips implement a 3 state logic, high, low and middle for example.

    You can also think of analog as digital with infinite States.
     
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