[Simh] Way out idea for simh

Wed Apr 20 13:54:29 EDT 2016

I readily admit that I know nothing about the OSes that run under simh except RTE and unix. If a machine doesn't have support for a randomly accessible block device without a native file system, then this scheme wouldn't be usable.

But I'm guessing most simh OSes support either raw disks or seekable tapes, and either would work.

From: skyvis at sky-visions.com [mailto:skyvis at sky-visions.com]
Sent: Wednesday, April 20, 2016 1:49 PM
To: Ken Cornetet <Ken.Cornetet at kimballelectronics.com>; skyvis at sky-visions.com; paulkoning at comcast.net; sampsa at mac.com
Cc: simh at trailing-edge.com
Subject: RE: RE: [Simh] Way out idea for simh

I think you are missing something. For the B5500 the drives are all one file system. If you add a drive, it becomes part of the file system. Also there is no way to access the drives in a raw way. For the I7000 series there is no concept of a file system to speak of. Similar for CDC 6600 for anything prior to Scope 3.4, the drives are all one big file system.

 Rich

------- Original Message ------- On 4/20/2016 1:20 PM Ken Cornetet wrote:

You don't need the notion of mountable disk. The disk would appear attached to the guest OS 100% of the time.

The guest doesn't need to be able to mount foreign file systems. The guest OS only considers that block device as a seekable collection of blocks.  All file movement between the LIF block device and the OS's native file system would be by a userland  utility.

True, this utility would have to be developed for every guest OS running under simh, but if the file system was simple enough, the code would be trivial.

From: Simh [mailto:simh-bounces at trailing-edge.com] On Behalf Of skyvis at sky-visions.com<mailto:skyvis at sky-visions.com>
Sent: Wednesday, April 20, 2016 1:04 PM
To: paulkoning at comcast.net<mailto:paulkoning at comcast.net>; sampsa at mac.com<mailto:sampsa at mac.com>
Cc: simh at trailing-edge.com<mailto:simh at trailing-edge.com>
Subject: Re: [Simh] Way out idea for simh

Just to add some info to the discussion. This sounds like a nice idea,
however it will be very difficult to implement on some of the older
machines that SimH supports.

For example the B5500 does not have the concept of a mountable pack.
Drives could be attached, but they were a permanent attachment. For the
Ibm 7000 line, most did not support disk. The disk drive that was
supported by many of the machines was a large box that you could not
put drives into (IBM 1301/2301). Also these machines all worked in BCD
(6 bit), not Ascii. I am also not sure when TOPS10 got support for
mounting foreign file systems. I don't believe that 6.03 or 5.03
support this idea.

Tapes, paper tapes, and punch cards are probably the most universal
format. Also a Paper tape reader is pretty easy to implement, it might
be possible to put some kind of header onto the tape to indicate the
name of the file. But take a look at how much trouble Kermit does to
handle all the various systems.

Rich

------- Original Message -------
On 4/20/2016 12:14 PM Paul Koning wrote:

> On Apr 20, 2016, at 12:06 PM, Sampsa Laine wrote:

>

>

>> On 20 Apr 2016, at 19:02, Paul Koning 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.

No, it would work for VMS, and level 1 at least would work for RSX, but neither RSTS nor RT11 understand it. And it's a complex file system, more so than the RSTS one and vastly more than RT11. It does more, of course, but if you're looking for something that can easily be ported to another system, this won't do.

I took the proposal to mean: find a simple OS for which you can easily implement an application to handle it on most operating systems. So think something handled by an application like PDP-10 FLX (or RT-11 FLX), not a file system with native support.

> ...

>>

>> 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.

One key question is how important it is to transfer a bunch of files all at once. Is it sufficient to send one file at a time? With scripting, that may not be all that problematic.

paul

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==========================================================================
Richard Cornwell
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========================================================================== Richard Cornwell skyvis at sky-visions.com<mailto:skyvis at sky-visions.com> http://sky-visions.com ==========================================================================
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