[Info-vax] VMS internals design, was: Re: BASIC and AST routines

[Arne Vajhøj]

On 11/25/2021 4:04 PM, Bill Gunshannon wrote:
> On 11/25/21 2:20 PM, Arne Vajhøj wrote:
>> Those running VMS today are mostly those without an easy way off
>> VMS.
> 
> I would really like to know what people could be running on
> VMS on an Itanic that would be so difficult to move to a
> totally different system.  Any applications are almost
> guaranteed to be written in an HLL.  Just what is it that
> they are doing on VMS that can not be done on another
> system?

It can be done on another OS.

But the cost and risk migrating can be significant.

VMS specific language extensions, SYS$ and LIB$ calls,
reliance on special features in Rdb or index-sequential
files not available in other RDBMS or ISAM, huge amount
of DCL scripts, Macro-32 pieces etc.etc..

A thousand easily solvable problems can when combined
be a very problematic cost and risk (risk may very
well be considered a bigger problem than cost).

It obviously depend on how the code is written. Some
C or Cobol programs may be pretty easy to migrate.
Most Pascal and Basic programs would be a rewrite from
scratch to migrate.

Arne