DuckCorp Dico

Found one definition

1.                 From The Jargon File (version 4.4.7, 29 Dec 2003):
                   
   
   
                   
                     
   RTI
    /R·T·I/, interj.
       The mnemonic for the ‘return from interrupt’ instruction on many computers
       including the 6502 and 6800. The variant RETI is found among Z80 hackers.
       Equivalent to “Now, where was I?” or used to end a conversational
       digression. See pop.