windows3-1  Exercise 1: Is Available Really Free Plus Standby?
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Verification: Level 1 (read-only; run on the author's machine, no administrator rights).

Prediction (work this out before running the script):

  Available should equal Free & Zero plus the three Standby counters (normal priority,
  reserve, core), so the difference should be 0 MB or within a few MB, because the five
  counters are read in one Get-Counter call. Free should be a small share of RAM, well
  under 10 %, with the bulk of Available being standby cache.

ex1.ps1 (run it with:  powershell -ExecutionPolicy Bypass -File ex1.ps1):

  # ex1.ps1: is Available really Free + Standby?
  $names = '\Memory\Available Bytes', '\Memory\Free & Zero Page List Bytes',
           '\Memory\Standby Cache Normal Priority Bytes', '\Memory\Standby Cache Reserve Bytes',
           '\Memory\Standby Cache Core Bytes'
  $v = @{}
  foreach ($s in (Get-Counter $names).CounterSamples) { $v[($s.Path -split '\\')[-1]] = $s.CookedValue }
  $standby = $v['standby cache normal priority bytes'] + $v['standby cache reserve bytes'] + $v['standby cache core bytes']
  $sum = $v['free & zero page list bytes'] + $standby
  'Available        : {0,8:N3} GB' -f ($v['available bytes'] / 1GB)
  'Free + Standby   : {0,8:N3} GB' -f ($sum / 1GB)
  'Difference       : {0,8:N1} MB' -f (($v['available bytes'] - $sum) / 1MB)
  'Free as % of RAM : {0,8:N1} %' -f (100 * $v['free & zero page list bytes'] / (Get-CimInstance Win32_ComputerSystem).TotalPhysicalMemory)

Output (real, from the author's machine on 2026-10-24; your numbers will differ):

  Available        :   15.828 GB
  Free + Standby   :   15.828 GB
  Difference       :      0.0 MB
  Free as % of RAM :      6.6 %

WHY THIS WORKS AS AN ANSWER
---------------------------
  The difference is exactly 0.0 MB, so Available is made of the free list and the standby
  lists and of nothing else. Only 6.6 % of the usable RAM is on the free list, but 15.83 GB
  (more than half) is available. That is why "my free memory is nearly zero" is not a
  diagnosis: standby pages are cached data that Windows can reuse at once.
  Common mistakes: forgetting one of the three Standby counters (the sum then falls short by
  the size of the missing one, often hundreds of MB); reading the counters in separate calls
  so that they change between reads; and treating "Free" in a Win32_OperatingSystem property
  as the free page list without checking what it counts.