[Info-vax] RSTS/E and VMS connection

[Arne Vajhøj]

On 4/9/2023 12:15 PM, Johnny Billquist wrote:
> On 2023-04-08 00:26, Arne Vajhøj 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.
>>
>> Before my time (I started with 4.4) but I thought the 9+3 to
>> 39+39 change happened with VMS 3.x -> 4.0 not with ODS-1 to ODS-2?
> 
> My earliest VMS was 3.6 or 3.7. Which seems to match very well with a 
> memory that it changed with V4.
> 
> But was it ODS-2 already at VMS V3? I guess it might have been, but I 
> thought the filename format, as well as directory structure hadn't 
> changed in ODS-2. But if you are right, then the ODS-2 spec must have 
> changed?

My understanding (but totally based on hearsay as it
is before my time) is that VMS had ODS-2 from day one
(but also supported ODS-1 for PDP-11 compatibility).

Arne