[Simh] RT-11 source

[Paul Koning]

> On Oct 26, 2016, at 3:06 PM, Rich Alderson <simh at alderson.users.panix.com> wrote:
> 
>> From: Johnny Billquist <bqt at softjar.se>
>> Date: Sun, 23 Oct 2016 03:11:05 +0200
> 
>> In fact, I would probably suggest Ray start with just writing some code 
>> to do some simple things without looking at existing code. The first 
>> thing needed would be to just have something that can load programs from 
>> a device, and run them. This will require some simple device driver, 
>> some simple file system, and a simple command line interpreter.
>       ^^^^^^^^^^^^^^^^^^
> 
> That's not even needed.  Beyond a 44 character file id in the VTOC on a disk,
> none of the IBM batch operating systems for the System/360 has what we would
> call a file system.  OS/360 requires the programmer to know how much space a
> file might occupy in its lifetime and allocate that (including overflow areas);
> DOS/360 requires the programmer to do all of that, *AND IN ADDITION* to define
> the exact location of the file on disk.  I don't think anyone would argue that
> those operating systems were unsuccessful in the marketplace.

That's true.  But since Ray is talking about doing this for educational purposes, it would make sense to limit the discussion to reasonably well designed operating systems -- which would exclude IBM products from the subject space.  Clearly by around 1960 or so, OS designers in many other companies understood how to do this sort of thing sanely.

	paul