VMS is UNIX spelled backwards (almost)

[Paul Campbell]

[slurp]

  I too must put my 5c in ... (first a bit about my background ... I port Un*x
for a living, I have also spent the last 4 years as a VMS hacker ... so I feel
I have a good view of both worlds).

  I feel the main reason for the 'enemity' between VMS and Un*x people is
a lack of knowledge and experience (here I mean YEARS of experience, what
you need to really understand an operating system's environment and feel
comfortable using it) on both sides. Here are my feelings about them ...

	1)	EDT vs vi - they are relatively similar in power for normal use

		vi:	good points - better search facilities, can work on
				almost any terminal
			bad points - impossible to learn/teach
		EDT:	good points - you can teach a novice computer user to
				use it in 15 minutes
			bad points - you have to use a DEC compatible terminal

	2a)	kernel hacking - VMS provides more 'hooks' than Un*x, but then
			you don't have the source (or objects) to reconfigure
			VMS, on the other hand allocation of system resources
			and the loading of device drivers is done dynamicly
			either at boot time or while the system is running.
			If you have the sources you can do 'anything' in Un*x,
			but in VMS you have the fiche and it is not necessary
			to change the kernal to do kernal things ... there are
			ways for a user program to get into kernal mode to do
			these things. Un*x does a few simple things well, VMS
			does these things and as well provides you with the 
			hooks do do many operating system things (page mapping
			signals, interrupts etc). I had to implement virtual 
			Un*x machines on VMS (with the Un*x kernal running in 
			Supervisor mode, each running with its own virtual
			disk (so we could give students 'virtual disk crashes'
			for them to recover from)) all the operating system
			things that you require are there, they are not in Un*x
			and I don't see how I could possibly do the same without
			a lot of Un*x kernal modification!

	2b)	kernel hacking cntd - I feel that the fact that VMS sources are
			not readily available is a major reason why people don't
			do more hacking, however DEC do give a good course on
			VMS internals and once you learn how to read the fiche
			you can do almost anything. Even though much of the
			VMS kernel is written in assembler there is no reason
			why you can't use almost any language for kernel code
			(I have used Pascal and FORTRAN). Bugs, DEC's support
			is really very good, it can take time for patches to
			arrive but if they are really critical they will get
			them to you express (I come from the furthest reaches
			of the world, the deep south of New Zealand).

	3)	portability - Un*x is portable, VMS is not (FULL STOP).
			
	I could go on for pages more ... but as a summary ... I feel that they
	are both good operating systems, each with a different emphasis and 
	that there are good reasons for using either one. Most of the points
	raised by both sides are probably to some extent valid and at the 
	same time can be shot down in FLAMES by the oposition. Finally just
	be glad you don't have a 43xx/370 etc, then we could all argue about
	the merits of many different operating systems rather than just two.

		Cheers

		Paul Campbell (ZL4TFW)   	..!ucbvax!unisoft!paul