In Fred Brook's Mythical Man Month chapter 4 (Aristocracy, Democracy, and System Design) page 49, he says:

As Blaauw points out, the total creative effort involves three distinct phase: architecture, implementation, and realization ...

implementer has plenty to do ... designing module boundaries, table structures, pass or phase breakdowns, algorithms, and all kinds of tools

...Meanwhile, on the realization level there is much to be done also. Programming has a technology, too. If the machine is a new one, much work must be done on subroutine convention, supervisory techniques, searching and sorting algorithm.

What is the difference between implementation and realization?

To me, an architecture is more related to specification descriptions or diagrams, whereas implementation is more to programming/coding, and it seems like the same as realization.

  • 7
    The realization is what happens when you send the app to QA and have the realization that it's a stinking pile. May 18, 2013 at 20:22
  • +1 Although not correct in the context, very true.
    – Random42
    May 19, 2013 at 17:06

2 Answers 2


The "new machine" part is key here. He's talking about what most people refer to nowadays as "low level programming." It's making a relatively machine-agnostic implementation work on a real machine. That includes things like standard libraries, drivers, compilers, linkers, kernels, filesystems, etc.

You could also consider system administration tasks as part of realization. You need physical hardware and a place to put it, cooling, user accounts, backup plans, redundancy, storage, network access, databases, etc.

In other words, you could have the greatest implementation in the world, but it does you no good unless it can be run on real hardware.

  • And I would include a stage beneath even that example, microcode in the embedded controllers.
    – JustinC
    May 20, 2013 at 4:47

I believe in this case, realization is deployment and integration of final product.

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