[Simh] Way out idea for simh

[Veit, Holger]

I think this is missing the actual problem. If a simh supported machine 
has some kind of (paper/magnetic) tape oder disk device, they are almost 
always physical files on the host system which can be attached/detached 
by simh console commands. What is in the files, a file system or bit 
stream or block structure, and what data encoding is used, is entirely 
depending on the emulated operating system. Since some simh emulators 
support different operating systems, like RT11/RSX11/Unix7 on a PDP-11, 
a built-in FTP API (or any other transfer utility, Zmodem, Kermit, etc.) 
must effectively know what OS is currently running.

Some structures, like Files-11, are well documented, other might not, or 
not fully. If the data structures used are sufficently known, whether 
simple or not, one can write host software that converts a user file and 
extracts or injects it into the expected data structure. There are 
numerous programs for all kinds of guest operating systems; and I have 
myself written some as well whenever I need them, but neither are such 
tools complete or portable, nor are they based on a widely accepted 
source format.

This leaves the burden to the target operating system to write a 
conversion tool that takes some input - from whatever source - and 
converts it into its own native file format. This is probably even more 
challenging, because unless it is an already supported input source, 
like a paper-tape reader or an emulated serial line, one needs to write 
some kind of device driver, or as suggested for RTE/6VM, some custom 
microcode instruction, to be surrounded by some native assembler or 
FORTRAN file (which leaves the open question whether this then can be 
reused in RTE/IVB, RTE-A, MPE etc. without major rewrites).

The Kermit approach appears to be most feasible for the moment, as it 
actually works through a supported input source, does the necessary 
conversion, and is anchored in the target operating system where fo 
which it exists. It should rather be analyzed why it doesn't seem to 
work on RTE - operating system issue, or simh emulation flaw? I remember 
having transferred numerous files between the HP1000 and the big VAX in 
a former life. Surely, certain file types won't work, but text is 
commonly possible. And for some special cases with IBM iron, there were 
native EBCDIC converters.

Surely it won't work for very old systems for which no Kermit exists, 
but then also some other means like an FTP API wont' help either.

The terminal emulation issue that only QCterm might be usable with 
HP1000 is a different topic, but it is a related general problem: not 
every system can deal with the lingua franca VT-100/ANSI, and not all 
terminal emulators work correctly.

Holger

Am 20.04.2016 um 20:48 schrieb Ken Cornetet:
> Again, you don't need OS support for foreign file systems, you just need to be able to read the disk blocks in a raw mode.
>
> -----Original Message-----
> From: Simh [mailto:simh-bounces at trailing-edge.com] On Behalf Of Rich Alderson
> Sent: Wednesday, April 20, 2016 2:31 PM
> To: simh at trailing-edge.com
> Subject: Re: [Simh] Way out idea for simh
>
>> Date: Wed, 20 Apr 2016 17:04:18 +0000
>> From: skyvis at sky-visions.com
>> 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.
> As of 7.05 (the very last maintenance release, from 1990) it still hadn't.
> I work with it daily.
>
>                                                                  Rich _______________________________________________
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