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OpenVMS Undocumented Features

This is the most complete collection of undocumented features we can find for OpenVMS. Some of these have been around since the time when it was called VMS while others are more current and have been added to OpenVMS V8.n. These features:

  • Are NOT documented (if they were, they wouldn't belong here)
  • Are NOT supported by PARSEC Group or HP
  • Are NOT guaranteed to work
  • May NOT exist in all versions of OpenVMS; past, present and future
  • Are subject to change, removal, enhancement or being documented at the whim of OpenVMS engineering
  • May be fun to know the next time you play OpenVMS trivial pursuit
  • May help you get your job done easier and faster
  • May help you impress your boss with your knowledge of the obscure

F$GETSYI arguments

The following arguments to the F$GETSYI lexical function are not documented.

Undocumented Arguments to F$GETSYI
Argument Description
ACTIVE_CORE_CNT Count of cores in hard partition with at least one active LP
ACTIVE_CPU_BITMAP CBB bitmap data of active CPUs
AVAIL_CPU_BITMAP CBB bitmap data of available CPUs
AVAIL_PAGES Available physical pages
AWSMIN_SYS AWSMIN for the system working set
AWSTIME_SYS AWSTIME for the system working set
BAP_MAX_PA_REG Bus addressable pool (BAP) maximum PA registered (megabytes)
BAP_MAX_REQ_SZ Bus addressable pool (BAP) maximum size requested (bytes)
BAP_MIN_PA_REG Bus addressable pool (BAP) minimum PA registered (megabytes)
BAP_MIN_REQ_SZ Bus addressable pool (BAP) minimum size requested (bytes)
CLUSTER_NTIME Cluster New time
CLUSTER_NTIME_REF Cluster New time - local reference
COMPLEX_ID Complex Profile ID
CPUCONF CPU Configuration bitmask: 0 through 31
CPU_SOCKETS Returns number of cpu sockets
DAY_OVERRIDE UAF day classifications are overridden
DAY_SECONDARY UAF day override is to Secondary
DBGTK_LOADED Remote system debugger target kernel is loaded
DEF_PRIO_MAX MAX priority for default policy
DEF_PRIO_MIN MIN priority for default policy
FT_ACTIVE CIRRUS system is fully active
FT_FLAGS Fault Tolerance Flags field
GLX_INCARNATION galaxy incarnation count
GLX_MBR_INCARNATION galaxy member incarnation number
GLX_MBR_JOINED galaxy member join time
GLX_SW_VERSION Galaxy software version
GLX_TERMINATION systime galaxy died
HP_CORE_CNT Count of unique cores in hard partition
H_FLOAT_EMULATED H floating instructions emulated
MAX_PFN Returns contents of MMG$GL_MAXPFN
MAX_PFN_64 Returns contents of MMG$GQ_MAXPFN
MIN_CPU_FEATURE_MASK AMASK value of all CPUs ANDed together
PFN_MEMORY_MAP Returns a physical memory map
PFN_MEMORY_MAP_64 Returns a 64 bit physical memory map
PFRATH_SYS PFRATH for the system working set
PFRATL_SYS PFRATL for the system working set
PMD_COUNT Returns count of phys. mem. desc. in HWRPB
POTENTIAL_CPU_BITMAP CBB bitmap data of potential CPUs
POWERED_CPU_BITMAP CBB bitmap data of powered on CPUs
PRESENT_CPU_BITMAP CBB bitmap data of present CPUs
PROCESS_SPACE_LIMIT Highest process private VA
PSXRR_PRIO_MAX MAX priority for POSIX Rnd-Robbin policy
PSXRR_PRIO_MIN MIN priority for POSIX Rnd-Robbin policy
PTES_PER_PAGE Page Table Entries per Page
PT_BASE Base VA of PT_space
QUORUM Connection manager cluster QUORUM
REALTIME_SPTS SPT entries for CONINTERR processes
RMS_GBLBUFQUO RMS global buffer quota
SERIAL_NUMBER System Serial Number
SHARED_VA_PTES Boundary between process and system space PTEs
SWPALLOCINC Swap file allocation increment value
WSDEC_SYS WSDEC for the system working set
WSINC_SYS WSINC for the system working set
WS_OPA0 Workstation using QVSS for OPA0
XCPU CPU subtype (Extended SID info)
XSID Extended System Identification Register


The SERIAL_NUMBER argument to F$GETSYI lexical function normally returns a formatted serial number in ASCII readable text as in the example below.

$ write sys$output f$getsyi("serial_number")

On some systems, it may return a string of 32 characters representing the binary value of the serial number. This may be translated to the ASCII text using the procedure below.

$ say := write sys$output
$ snum = f$gets("SERIAL_NUMBER")
$ if f$len( snum ) .eq. 32 then -
$ gosub decode_snum
$ node = f$getsyi("nodename" )
$ hdwe_name = F$GETSYI("HW_NAME")
$ say f$fao( " Node !AS (!AS), serial nbr !AS", node, hdwe_name, snum )
$ exit
$ tsnum :=
$ ptr = 0
$ disp = 32 - (ptr * 2)
$ hex = f$extr( disp - 2, 2, snum )
$ stbit = ptr * 8
$ if %X'hex' .ne. 0 then -
$ tsnum['stbit',8]=%X'hex'
$ ptr = ptr + 1
$ if ptr .lt. 16 then -
$ goto decode_loop
$ snum = tsnum
$ return

Thanks to David Dachtera at DJE Systems for providing this tip.

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Please enjoy these features at your own risk. If you are aware of other features in OpenVMS which are currently undocumented, you may use our inquiry form to inform us. We may then add it to our list.