[Simh] 8" Floppy disk image getting HALT error

[Kevin Handy]

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> 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             ||  Reading murder books
> pdp is alive!                     ||  tryin' to stay hip" - B. Idol
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