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Re: [cosmacelf] Re: My 1802 has been running code for me for 32 years today!

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  • Lee Hart
    ... There is a fuzzy border between a true HLL (High Level Language), and a CPU that truly executes machine code. Lots of HLL compile into a byte code, which
    Message 1 of 28 , Apr 29, 2013
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      On 4/29/2013 12:12 PM, jdrose_8_bit wrote:
      > I knew about the FORTH processors. Thank you. However, I was thinking
      > there are microprocessors that run even higher level languages like
      > BASIC, Java and FORTRAN natively. Perhaps I am mistaken in how they
      > operate.

      There is a fuzzy border between a true HLL (High Level Language), and a
      CPU that truly executes machine code.

      Lots of HLL compile into a byte code, which is a compacted form that is
      easier for a real CPU to emulate. The byte code then gets compiled or
      interpreted into the CPU's native instruction set. Smalltalk, BASIC,
      ucsdPascal, FORTH, and Java are some examples that come to mind.

      But in a few cases, CPUs have been built that can "directly" execute one
      of these byte codes. The trouble is that "directly" often means by using
      microcode, or a program in ROM. In effect, they modified the CPU's
      native instruction set to be more like the byte code. Smalltalk, the
      LISP machine, and Moore's FORTH engines took this approach. The CPU
      doesn't literally execute the English language version of the source,
      but it does directly execute the byte code.

      In the past, the amount of hardware needed to directly execute source
      code would have been staggering. But today, it's not all that hard to
      imagine doing, especially with HLLs that aren't all that "high".
      --
      If we knew what we were doing, it wouldn't be called research, would it?
      -- Albert Einstein
      --
      Lee A. Hart, http://www.sunrise-ev.com/LeesEVs.htm
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