Purely out of interest, how would I diassemble a DEC C routine on VAX/VMS? Can I use DEBUG to do this? Yes, you can use DEBUG for this. Better still, use the public domain DISM32 by Andrew Pavlin. I can't remember where I got it but even if it is not on the freeware cds, it should not be too difficult to locate it. If not, I can provide a copy. If you don't get a compiled version, you need a FORTRAN compiler to build it. DISM32 takes a VAX executable/sharable/system image and generates assembler source which can be run back through the MACRO assembler. Some tweaking may be required before it will assemble properly. More tweaking may be required to correctly differentiate between code and data in all cases, although it does a pretty good job in general. It is especially good with device drivers and knows how to regenerate many/most of the macros used to assemble them. It is also very good with ordinary user mode code. It can get confused by code sections that never get called and by some calculated addresses but it is possible to give it hints about these and run it iteratively to achieve an acceptable result. You can use DISM32 on SYS$LIBRARY:DECC$SHR.EXE or an executable image linked with SYS$LIBRARY:DECC$CRTL.OLB to disassemble bits of the C runtime library. Unfortunately, some of the constructs uses by C compilers can look pretty obscure when viewed as assembly language. If bits of the runtime library are originally written in assembly, they will likely be easier to figure out. Regards, Peter Coghlan.