The argument MAIN_MEMORY to the F$GETSYI lexical function returns a string of numbers indicating the use of memory on the system. The following command procedure extracts and displays the information

$! memory.com
$ delete /symbol /all /local
$ a_mem = f$getsyi(\"main_memory\")
$ modified = f$integer (\"%x\'\'f$extract(0, 8, a_mem)\'\")
$ inuse = f$integer (\"%x\'\'f$extract(8, 8, a_mem)\'\")
$ free = f$integer (\"%x\'\'f$extract(16, 8, a_mem)\'\")
$ total = f$integer (\"%x\'\'f$extract(24, 8, a_mem)\'\")
$ show symbol /all /local $ show memory /physical $ exit
$ @memory  
A_MEM     = \"00000B1400012D160000C7D600020000\"  
FREE      = 51158  Hex = 0000C7D6 Octal = 00000143726  
INUSE     = 77078  Hex = 00012D16 Octal = 00000226426  
MODIFIED  = 2836   Hex = 00000B14 Octal = 00000005424  
TOTAL     = 131072 Hex = 00020000 Octal = 00000400000