Z88 Developers' Notes
Contents   Contents of System Calls

OS_Dor, the DOR interface

RST 20H, DEFB $87

IN: 

     A = reason code
     HL, IX arguments

     Reason codes are as follows:

     DR_GET ($01)   get handle for a DOR name (internal use)
     DR_DUP ($02)   duplicate DOR
     DR_SIB ($03)   return brother DOR
     DR_SON ($04)   return child DOR
     DR_FRE ($05)   free DOR handle
     DR_CRE ($06)   create blank DOR
     DR_DEL ($07)   delete DOR
     DR_INS ($08)   insert DOR
     DR_RD ($09)    read DOR record
     DR_WR ($0A)    write DOR record
OUT, if call successful: 
     Fc = 0
     returned values depend on A(in)
OUT, if call failed: 
     Fc = 1
     A = error code:
          RC_HAND ($08), bad handle
          RC_BAD ($04), bad argument
          RC_ROOM ($07), no room
          RC_EOF ($09), end of file
Registers changed after return: 
     not documented.
Notes:
When the last DOR record in a list has been read, an RC_EOF is reported and the handle is immediatly released, ie. it will not be necessary to release the handle with a DR_FRE call.
Bugs:
Corrupts the stack pointer SP when called with an old handle, e.g. when a previous DR_ call resulted in a "End of list" error (RC_EOF).
Reason code specifications:

DR_GET ($01), get a handle for a DOR name (internal usage)

IN: 

     HL = pointer to a string (full path with device name)
OUT, if call successful: 
     Fc = 0
     IX = DOR handle
     A = minor type
Registers changed after return: 
     ..BCDEHL/..IY same
     AF....../IX.. different
Notes:
Do not use this call. Instead use GN_Opf with A = OP_DOR to obtain a DOR handle.
DR_DUP ($02), duplicate DOR

IN: 

     IX = DOR handle
OUT, if call successful: 
     Fc = 0
     BC = duplicate DOR handle (IX is still valid)
OUT, if call failed: 
     Fc = 1
     BC = 0 (IX is still valid)
     A = error code
          RC_HAND ($08), bad DOR handle
Registers changed after return: 
     ....DEHL/IXIY same
     AFBC..../.... different
DR_SIB ($03), return brother DOR

IN: 

     IX = DOR handle
OUT, if call successful: 
     Fc = 0
     IX = next DOR handle (original IX invalid)
     A = minor type
OUT, if call failed: 
     Fc = 1
     A = error code
          RC_HAND ($08), bad DOR handle
Registers changed after return: 
     ..BCDEHL/..IY same
     AF....../IX.. different
DR_SON ($04), return child DOR

IN: 

     IX = DOR handle
OUT, if call successful: 
     Fc = 0
     IX = child DOR handle (original IX invalid)
     A = minor type
OUT, if call failed: 
     Fc = 1
     A = error code
          RC_HAND ($08), bad DOR handle
Registers changed after return: 
     ..BCDEHL/..IY same
     AF....../IX.. different
DR_FRE ($05), free DOR handle

IN: 

     IX = DOR handle
OUT, if call successful: 
     Fc = 0
     IX = 0
OUT, if call failed: 
     Fc = 1
     A = error code
          RC_HAND ($08), bad DOR handle
Registers changed after return: 
     ..BCDEHL/..IY same
     AF....../IX.. different
DR_CRE ($06), create blank DOR

IN: 

     IX = parent DOR handle
     B = minor type
OUT, if call successful: 
     Fc = 0
     IX = new DOR handle (original IX invalid)
OUT, if call failed: 
     Fc = 1
     A = error code
          RC_HAND ($08), bad DOR handle
          RC_BAD ($04), bad argument
          RC_ROOM ($07), no room
Registers changed after return: 
     ..BCDEHL/..IY same
     AF....../IX.. different
DR_DEL ($07), delete DOR

IN: 

     IX = DOR handle
OUT, if call successful: 
     Fc = 0, DOR deleted
     IX = 0
OUT, if call failed: 
     Fc = 1
     A = error code
          RC_HAND ($08), bad DOR handle
Registers changed after return: 
     ..BCDEHL/..IY same
     AF....../IX.. different
DR_INS ($08), insert DOR

IN: 

     BC = parent DOR handle
     IX = DOR handle
OUT, if call successful: 
     Fc = 0
     original BC and IX DOR handles are still valid
OUT, if call failed: 
     Fc = 1
     BC and IX is still valid
     A = error code
          RC_HAND ($08), bad DOR handle
Registers changed after return: 
     ..BCDEHL/IXIY same
     AF....../.... different
DR_RD ($09), read DOR record

IN: 

     B = record type
     C = buffer length
     DE = user buffer address (to store information of read)
     IX = DOR handle
OUT, if call successful: 
     Fc = 0
     original IX DOR handle is still valid
     C = actual length of information
OUT, if call failed: 
     Fc = 1
     original IX is still valid
     A = error code
          RC_HAND ($08), bad DOR handle
          RC_BAD ($04), bad argument
          RC_FAIL ($16), information is not present
Registers changed after return: 
     ..B.DEHL/IXIY same
     AF.C..../.... different
DR_WR ($0A), write DOR record

IN: 

     B = record type
     C = buffer length
     DE = user buffer address (to copy information of store)
     IX = DOR handle
OUT, if call successful: 
     Fc = 0
     original IX DOR handle is still valid
OUT, if call failed: 
     Fc = 1
     original IX is still valid
     A = error code
          RC_HAND ($08), bad DOR handle
          RC_BAD ($04), bad argument
Registers changed after return: 
     ..BCDEHL/IXIY same
     AF....../.... different