[Simh] Transferring the licence file to the VAX emulator

[Johnny Billquist]

On 2018-12-17 21:34, Phil Budne wrote:
> I wasn't saying RMS was anything new to the world in general, but that
> VMS was the first system to make it the preferred way to access disks.
> DEC was not always thus.
> 
> I'm pretty sure my first exposure to RSX-11M was using F11ACP, I don't
> think RSX was BORN with RMS as the primary method of file access, it
> was born as a real-time system.

To clarify a couple of things here. F11ACP is the low level file system 
processor. Both RSX and VMS have this one.
(In VMS, you have different flavors to handle ODS-1, ODS-2 and ODS-5, 
and also the water got muddled by the addition of the XQP in order to 
reduce the number of context switches when trivial file operations were 
being performed.)

The ACP have nothing to do with what RMS does. RMS is a layer above the 
ACP. In the old days, RSX used a library called FCS. FCS can be called 
more or less a subset of RMS. Both FCS and RMS provide similar 
capabilities, such as viewing files as a stream of records or bytes, 
instead of just being a bunch of disk blocks, which is all that the ACP 
gives you. And the formats FCS use on the disk are compatible with, or a 
subset of the formats RMS use.

RMS was definitely an option in RSX. Probably even before VMS was born. 
But it was an option. When you do a system generation of RSX-11M, you 
get asked if you want to include RMS or not. There are some 
functionality that is provided by the ACP, which RMS needs, but FCS do 
not, so therefore it matters at system generation time. But otherwise, 
RMS, just like FCS, is just a user level library in RSX.

I sortof doubt you ever used F11ACP without FCS, even though it is 
definitely possible. But DEC never documented the ACP interface very 
well, so it's a bit tricky to use it. And then of course, you also need 
to write all the annoying bits that FCS already implemented for you.

> Clem wrote:
>> As Dennis Ritchie once said to me, the whole idea behind a byte stream was
>> for the OS to just get the bits and then user code do the interpretation
> 
> This was pretty much the norm at DEC before RMS.  Disk blocks contained
> streams of bytes.  Legend is the original name of PIP was ATLATL
> (anything lord to anything lord).

I wouldn't say so. It depends on the OS.
TOPS-10 and Tops-20 are both rather stream like I seem to remember.
RSTS/E is a bit of a hybrid, I think. (If I remember right)
Same for RT-11, as well as OS/8. You address things in blocks, and you 
have to fiddle around with the bytes yourself, but the normal convention 
is that you just add CR+LF in the file when there is a new line. And you 
have something like ^Z to indicate the end of file, since file sizes are 
actually expressed in blocks, and not bytes.

And RMS was the successor to FCS, which have a very similar paradigm. 
But I think most agree that RSX was sortof the odd one out compared to 
most of the other systems at the time at DEC.
But you always had some library to be able to just read/write data to a 
file, and that library blocked and deblocked the data for you.
It's just that FCS (and later RMS) had a much more complex (and rich) 
set of formats on the disk for it. Good and bad...

	Johnny

-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol