[Info-vax] RSTS/E and VMS connection

[Johnny Billquist]

On 2023-04-08 03:05, Dave Froble wrote:
> On 4/7/2023 5:22 PM, Johnny Billquist wrote:
>> On 2023-04-07 01:02, bill wrote:
>>>
>>> WE have often heard that VMS on the VAX was the logical procession
>>> from RS11 on the PDP.  I was looking around at my bookshelf and saw
>>> my 1983-84 RSTS/E PDP-11 Operating System book and it kinda piqued
>>> my interest so I picked it up and did a  little lite reading.
>>
>> Well. Internally, VMS is like a scaled up RSX in many (most?) corners. 
>> Most data
>> structures and designs were (are) more or less the same as in RSX, but 
>> scaled up
>> for 32-bits and whatever logically came out from there. A lot of 
>> system calls is
>> the same story. And initial release of VMS mostly used all RSX cusps, 
>> running in
>> compatibility mode, and slowly getting replaced with native things. Early
>> versions of VMS I seem to remember even might still have used ODS-1, 
>> or some
>> hybrid between ODS-1 and -2. I clearly remember the 9+3 character 
>> filename
>> limitation in my earliest memories of VMS.
>>
>> However, at the user interface level, VMS was clearly taking it's 
>> queues from
>> RSTS/E. Including having the BASIC+ SYS() calls compatibly working in 
>> VMS. And
>> things like ^C actually stopping the program, unlike under RSX, where 
>> it just
>> gives you the CLI prompt.
>>
>>> And there is another note about "The RSTS/E and VAX/VMS Compatbility
>>> Manual".  I would love to see a copy of that.
>>
>> There was also a manual/book about moving from RSX to VMS published. I 
>> think DEC
>> tried to address both crowds, and convince them both to migrate to 
>> VMS. However,
>> I think they were much more successful in convincing the RSTS/E guys.
>>
>>   Johnny
>>
> 
> Well, virtual address space was sort of a rather large hammer ...

Yes. Scaled up quite a lot. But virtual addresses as such was already 
there on the PDP-11. Remember: VAX -> Virtual Address *eXtension*.

   Johnny