Enquiries

The OS_Nq call is used to read the system parameters, including information on the screen, memory, available streams and settings from the Panel and Printer Editor. A call is made by loading the BC register with a reason code (the system parameter mnemonic) and the other registers with values specific to that reason code. Register changes and output specifications are different for each reason code.

Here is the call specification:

RST 20H, DEFB $66

IN:
            BC = reason code
            ADEHLIX parameters
 
OUT if call succeeded:
            Fc = 0
            Depends on BC and other arguments
 
Out if call failed:
            Fc = 1
            A = return code:
                        RC_BAD ($04), incorrect reason code or parameters
                        RC_UNK ($03), unknown request

The following enquiry calls are for fetching low level window information:

NQ_WBOX (BC = $8300), return window information NQ_WCUR (BC = $8303), return cursor information NQ_RDS (BC = $8306), read text from the screen

The above window enquiry calls are described in detail in the OS_Nq call specification. 

Process Management

The following codes return system handles in IX:

NQ_Ain ($8600)          application enquiry (system use only)
NQ_Khn ($8603)          read keyboard handle (use ":INP" device instead)
NQ_Shn ($8606)          read screen handle (use ":SCR" device instead)
NQ_Phn ($8609)          read printer indirected handle
NQ_Nhn ($860C)          read null handle (use ":NUL" device instead)
NQ_Wai ($860F)          who am I? (system use only)
NQ_Com ($8612)          read comms handle (use ":COM" device instead)
NQ_Ihn ($8615)          read IN handle (use ":INP" device instead)
NQ_Ohn ($8618)          read OUT handle (use ":OUT" device instead)
NQ_Rhn ($861B)          read direct printer handle
NQ_Voz ($861E)          application verifies running OZ version (OZ V4.5 and newer)
NQ_Roz ($8621)          read OZ revision number (OZ V4.5 and newer)
NQ_Btl ($8624)          read battery status (OZ V4.5 and newer)

Memory Management 

NQ_Mfs ($8900)          read free space information (system use only)
NQ_Slt ($8903)          read slot type information (system use only)
NQ_Mfp ($8906)          get total of free RAM pages in slot (OZ 4.2 and newer)

Director and CLI 

These enquiries return extended pointers of a null-terminated string in BHL:

NQ_Dev ($8C00)          fetch current device
NQ_Dir ($8C03)          fetch current directory
NQ_Fnm ($8C06)          fetch current filename match string

Director and CLI handles 

The following calls return system handles in IX

NQ_Dmh ($8C09)          fetch Director special memory handle (system use only)
NQ_Inp ($8C0C)          read std. input handle
NQ_Out ($8C0F)          read std. output handle
NQ_Prt ($8C12)          read printer stream handle
NQ_Tin ($8C15)          read input-T handle
NQ_Tot ($8C18)          read output-T handle
NQ_Tpr ($8C1B)          read printer-T stream handle
NQ_Chn ($8C1E)          read comms handle