nagy%43198.hepnet@LBL.ARPA.UUCP (03/23/87)
>I need to know if Ultrix & VMS can be run interchangeably on the same >microvax. A faculty member here is considering doing the evaluation of >several types of software, where versions exist that run on 4.2BSD, >and on VMS. What difficulties are involved in switching between one >operating system and the other? Do they need to each be put on separate >disks, or can they share the same disk? Can software written for >a VAX 750 (UNIX or VMS) run just as easily on a microvax II? 1. VMS and Ultrix use (radically) different file structures so you will need two disk drives. To switch between them involves shutting down the current system and booting the new system. 2. To the best of my knowledge, you will have BIG problems reading files on the Ultrix disk from VMS and vice versa. Maybe someone else out in net-land can help you with this one. 3. Under VMS, a VAX is a VAX, be it a MicroVAX for an 8800. Software written on, compiled on and linked on one will run (the .EXE file) on the other. At boot time, VMS loads the necessary code modules needed on the MicroVAX to emulate those instructions not part of the MicroVAX architecture but part of the full VAX architecture. So your program will run, except for performance considerations (note: for PDP-11 compatibility mode, you need the VAX-11/RSX product which will provide a software emulator for PDP-11 instructions on MicroVAXes and the newer 8xxx machines).
scc@computer-lab.cambridge.ac.UK.UUCP (04/04/87)
In a previous article, nagy%43198.hepnet@arpa.lbl (nagy) wrote: > To the best of my knowledge, you will have BIG problems reading files > on the Ultrix disk from VMS and vice versa. Maybe someone else out > in net-land can help you with this one. Hmm ... Talking off the top of my head, I think that it would not be too difficult to come up with a VMS program that reads files from an ULTRIX partition. I'd start from the source code for ULTRIXes standalone libraries (the ones that are used by the boot program and so on). These have the capability to follow a pathname from a partition's root directory, and read a file. All this stuff is written in C. It would be necessary to replace the calls into the standalone disc device driver with the appropriate VMS stuff to read blocks from the ULTRIX partition, but that shouldn't be much of a problem. [You might find that the standalone libraries do not understand ULTRIX symbolic links ... but that is no great loss, and it should be easy to implement if you need the facility]. Obviously I'm assuming that you have a VMS C compiler and legitimate access to the ULTRIX source code! Reading a VMS from ULTRIX would be much much harder. For a start, the VMS filesystem code is not written in any language that ULTRIX understands ... Disclaimer: Like I said at the beginning, I'm talking off the top of my head. If you believe me, thats your problem not mine! -- Steve