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8-bit, 32-bit, 64-bit Processors?

  1. Oct 4, 2011 #1
    Hello everybody,

    I want to ask what do 8-bit, 32-bit, 64-bit mean when it comes to processors.
  2. jcsd
  3. Oct 4, 2011 #2
    Re: Processor

    without getting too technical, it relates to the largest value a computer can store in one block of memory. bits refer to the number of digits in a binary number. Its also the way a computer counts and performs calculations

    the main thing you will see with the processor is the amount of RAM they can use.
    a 32 bit computer can count sequentially from 0 to 4294967295 (2^32-1) thats where the 32 bit comes from. this means it can deal with about 4GB of ram MAX

    a 64 bit computer can do 0 to 18446744073709551615 (2^64-1) it can use a LOT more ram.

    Maybe give this a read http://en.wikipedia.org/wiki/64-bit
  4. Oct 4, 2011 #3


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    Re: Processor

    The normal usage for 8 bit, 16 bit, 32 bit, 64 bit terminology for cpu's is a reference to the size of the primary registers in a cpu. One exception is the Motorola 68000, called a 16/32 bit cpu because it's registers are 32 bits wide, but it reads and writes memory 16 bits at a time. Intel cpu's didn't use this convention and the number of bits just referred to the primary registers.

    The Intel 8080, 8085, and Zilog Z80 are considered 8 bit cpus, because that was the size of their accumulators and most of their registers, although it's program counter was 16 bits, and specific pairs of registers could be combined to form 16 bit values or addresses.

    The Intel 8086 and 8088 are considered a 16 bit cpus, but the 8086 accesses memory 16 bits at a time, while the otherwise identical 8088 accesses memory 8 bits at a time. It had 20 bits for addressing memory (so it could support up to 1 MB). The main registers are 16 bits wide, but some of them can be accessed 8 bits at at time (AX can be accessed as AH (high order part) or AL (low order part)).

    The Intel 80386 is a 32 bit cpu. The 80386 normally accesses memory 32 bits at a time with a 32 bit addresses. Motorola 68000 16/32 bit processor has 32 bit regisers, but accesses memory 16 bits at a time with a 24 bit address. The Motorola 68020 accessed memory 32 bits at a time. The Intel Pentium Pro is also a 32 bit cpu, but some versions had 36 bits of addressing, that required using address translation schemes.

    For a typical PC, the amount of memory that can be read at one time varies with the motherboard and cpu, normally it's 64 bits (called double channel) or 96 bits (called triple channel).

    The previous post already posted a link to 64 bit cpus, links to the others:



  5. Oct 27, 2011 #4
    To simplify things even further, it generally refers to the maximum size (number of bits) that can be transferred at a time (from register to register).

    Think of a highway: a single-lane highway can transfer 1 car at a time (but several in line, or serially), whereas a four-lane highway can transfer 4 cars at a time. So the highway is analogous to a data bus and the cars are bits. The wider the bus (highway), the more bits (cars) that can be transferred at a time.
  6. Oct 27, 2011 #5
    Re: Processor

    Two years ago I bought a copy of Vista Ultimate that included both the 32-bit and 64-bit versions. At the time, it had 2 GB RAM, I thought that was sufficient, and I'd heard about problems with support for 64-bit drivers, so I loaded the 32-bit version.

    Things worked as advertised.

    This summer, I upgraded my hard drive and RAM, and reloaded the 32-bit version. It could only see 3 GB RAM. I remember hearing that the 64-bit version could support gobs of RAM, so I thought, "Why not give it a try?" and loaded the 64-bit version. It was a snap, I didn't have any problem whatsoever with any drivers, and it sees the full 4GB of RAM.
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