[Simh] 8" Floppy disk image getting HALT error

[Walker Sampson]

Hi everyone,

Thanks again for the help, this has been great. I’ve had a chance to loop back to this.

Tim, I’m not familiar with the VMS commands you’re referring to. Is this a virtual machine I can run – something like OpenVMS? I’m unclear on how to best access the content on the disk image as a file, given that it’s not a bootable disk the SIMH VMs can run.

Best,

Walker


From: Simh <simh-bounces at trailing-edge.com> on behalf of Kevin Handy <khandy21yo at gmail.com>
Date: Friday, July 14, 2017 at 3:21 PM
To: Johnny Billquist <bqt at softjar.se>
Cc: "simh at trailing-edge.com" <simh at trailing-edge.com>
Subject: Re: [Simh] 8" Floppy disk image getting HALT error

Just did a little research on WPS-8 floppy format, just to satisfy my curiosity.
WPS-8 stores data on an RX-50 as a series of 12-bit words, using two bytes on the floppy to store a word. The low 8 bits goes into the 1st byte, and the upper 4 go into the second btype.  4 bits in the secnd byte are unused.
It stores two 6-bit characters in each word. To convert it to asCII, mask off the 6 bits and add 31. Character 63 (ASCII 94) is a command character, and following character(s) specify the command. Some other characters are also special '[' and ']'  toggle upper/lower case.
Looking at a WPS-8 floppy in raw mode on a PC would not display anything readable, so this guys floppy is obviously not wps-8,and if all pdp-8s systems handled floppies the same way (as 12 bit words), it probabl isn't from any psp-8.



On Wed, Jul 12, 2017 at 4:33 AM, Johnny Billquist <bqt at softjar.se<mailto:bqt at softjar.se>> wrote:
On 2017-07-12 02:04, Timothe Litt wrote:
On 11-Jul-17 18:02, Johnny Billquist wrote:
On 2017-07-11 21:09, Timothe Litt wrote:
VMS mount /over=id /foreign is the quickest way to identify files-11 and
RT disks.  FILES-11 can be read directly; use EXCHANGE for RT-11.  Once
you have the disk mounted on VMS, you can network it to wherever you
like.

Similar story if you have RSX. I might have forgotten a thing or two
about VMS here, but I would have thought /OVER=ID/FOREIGN would not
then let you access the disk in the direct way if it is Files-11.
I was suggesting the easiest way to IDENTIFY the media.  /FOREIGN will
dump the filesystem type when it looks for a HOM block.  Once you know
that, you use the appropriate command / utility to access that type.

To access FILES-11 on VMS, you don't use /FOREIGN, just mount (though
/over=id will allow a private mount without knowing the volume label.)

Ok. Fair enough. I thought you meant that you'd mount it that way, and then go at it.
MOUNT and EXCHANGE details are available from HELP and the manuals.

VMS has, arguably, the most filesystem support and tools for this.  But
OS choice is a religion.  Use whatever you believe in & have available;
there is no point in arguing religion.

True. And, as with any religion, there is no point of even having an argument. Whatever works is good enough.
Of course, if the OP is more interested in the result than the process,
he can probably get one of us to extract the one file for him...

Also true. I'm sure plenty of people would help, if asked.


        Johnny

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