By MIPS/Alpha in the mid-late 90's there was a whole new debugger stream that had been developed at part of GEM, but there was another one that came from MIPs too which was based on dbx.
This raises a question I've always had - what was the relationship between DEC's compilers on MIPS/Alpha and the work the MIPS folks did? Early versions of OSF/1 on both platforms have tools that are very, very similar to the MIPS compiler suite - ugen, uopt, two-pass assembler, etc. - and I've always been curious what the heritage was there.
-Henry