QDOS Internals

Anything you never knew you wanted to know about the Sinclair QL.

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This trap finds the users of a Thing. The Trap cannot be used in the QDOS and SMSQ/E operating systems. Look at the Notes here for a solution.

Call ParametersReturn Parameters
D0.B$2CD0.LError code.
D2.LUnusedD2.LID of job owning the usage block.
A0.LPointer to Thing name.A0.LPreserved.
A1.LAddress of Thing usage block/0.A1.LNext usage block


ERR_NFThing not found.
ERR_NJUsage block not found.


  • All registers not shown above are not used on entry and are preserved on exit.
  • If A0 is zero on entry the Trap looks for the first user. If there is no user ERR_NJ is set. Otherwise A1 points to the usage block so that a re-entry to the Trap will cause it to find the next user.
qdosmsq/traps/trap_1/nthu.txt · Last modified: 2010/11/06 14:16 by george.gwilt