Display memory usage.
Syntax MEM MEM /C MEM /D MEM /P
/P List programs in memory with the memory address and size of each /D List Programs(as /P) and also Devices /C List programs in conventional memory and list programs in upper memory
MEM will only display details about the current CMD shell environment, programs running in a separate shell (or WIN32 programs) will not be listed - so it won't tell you anything about total memory usage.
"The palest ink is better than the sharpest memory" - Chinese proverb
CLEARMEM (Resource Kit) - Clear Memory Leaks
WINMSD - Windows NT Diagnostics (including Physical Memory)
GUI Task Manager - for all program details including Win32 applications.
TLIST - Task List
powershell: gwmi Win32_PhysicalMemory / gwmi Win32_ComputerSystem
Q184419 - DisablePagingExecutive (use when >500M RAM is available)
Q126962 - How to increase desktop heap memory for non-interactive processes
Memory Management.doc - explains allocation of memory address space (Microsoft)
3GB Startup Switch (this is very rarely needed)
Equivalent bash command (Linux): free -t - Display a summary of current memory usage and availability.