Ed Jaffe noted... >The oldest assembler I ever used was IFOX00. ISTR, it did not >have support for LOCTR but my memory could be faulty.
I think your memory is correct. As I remember the IFOX assembler used basically the four-pass structure of Assembler F. It was developed and supported by a group in Lidingo Sweden (a suburb of Stockholm?), and its popular publications were done by Jan Sandzelius. (The Swedish group attended several SHARE conferences while they were learning "skills transfers" from the assembler team in San Jose.) I believe LOCTR was introduced with Assembler H. Due to its having merged conditional assembly and ordinary-assembly pass 1, any time a location counter discontinuity was found it had to establish LOCTR-like temporary location counter that ASMH then resolved at the end of pass 1 in an "interlude". The LOCTR instruction was apparently a "public exposure" of this internal facility. More than you wanted to know, maybe...
