In this article, the author states that a 64bit processor can theoretically reference 2^64 bytes of memory. What does he mean by this statement, or rather the word, reference?

Also, I visualize the entire RAM to be divided into little memory cells, each having an n-bit binary number that represents a given instruction or value that is needed for running any program in the computer. Is this visualization right?

If it is, then for a 64bit processor, what would be the number of memory cells in the RAM?


No, the author is wrong.

I have used 32 bit processors that could address 64 GB of RAM. Memory is restricted by the number of address lines, multiplied by the number of bytes addressed by each individual value of address lines.

Address space of one application was limited to 4GB, but you could have a dozen applications running at the same time, each using several GB.

The author also seems to be quite ignorant of what processors and operating systems exist.

  • $\begingroup$ So what does the 32 in a "32bit processor" mean? $\endgroup$ – noorav Apr 25 at 13:50
  • $\begingroup$ It means “32”. Beyond that, things are complicated. Processor designers don’t feel restricted by arbitrary rules. $\endgroup$ – gnasher729 Apr 25 at 13:53
  • $\begingroup$ 32 what? It must have some meaning else they wouldn't put the 32 right. I'm new to this topic so I'd really like to get my fundamentals right $\endgroup$ – noorav Apr 25 at 14:00
  • $\begingroup$ What I said. It means 32, and then it gets complicated. $\endgroup$ – gnasher729 Apr 25 at 14:55
  • $\begingroup$ I'm sorry, but I'm not satisfied with the "just 32" answer. Could you explain the complicated part in a somewhat simple, yet understandable fashion? $\endgroup$ – noorav Apr 25 at 15:00

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