[Simh] Way out idea for simh

[Sampsa Laine]

> On 20 Apr 2016, at 19:02, Paul Koning <paulkoning at comcast.net> wrote:
> 
>> 
> 
> I don't know LIF, but the RT-11 file system is certainly simple.
> 
> There are a couple of complications.  First, you'd have to write a file access utility for each guest OS.  Given a simple enough file system that isn't necessarily a huge burden.  Then again, what might be simple, requiringly only modest code, on one machine might be a major burden on another simply because it has much less memory.
> 

For DEC stuff, Files-11 (level 2?) would probably work across most of the OSes.

> Another problem is that there isn't any universal disk format, so you're missing the foundation for a universal file format.  Consider the IBM 1620, with disks that have 200 digit sectors.  Or (not that SimH supports it, but another simulator does) CDC 6000 machines, where the sector size is 322 12-bit words.
> 

Yup this would have to be machine (or even OS) specific.

> Chances are that magnetic tape is more general; there aren't as many encodings there. Basically it's 6 bits vs. 8 bits per frame.  Everyone understands variable length data, and unlabeled tapes are fairly widely supported.  Even if not, writing a labeled tape with a single file on it isn't too hard.  You're still stuck with machines that have no magnetic tape support, there aren't all that many but certainly some.
> 
> Paper tape is yet a third option, which is presumably unlabeled but often transparent. (Not always, the 1620 comes to mind as a notorious example of a machine that could read only coded tape with punches conforming to the code it expects.)

That’s a good point but doesn’t make organising files trivial.

Sampsa


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