Re: Extracting files off “unknown” 8 inch disks. Any thoughts…

Fred Cisin cisin at
Thu May 4 17:24:43 CDT 2017

On Fri, 5 May 2017, Terry Stewart via cctalk wrote:
>> They may be CP/M, or some other format entirely.
> It turns out these disks are from a VAX machine. Assuming the OS is VMS, I
> scoured the Internet for something that might read them.

I don't know anything.    but, I will point out a few things to look into.

> Eventually I found Hunter Goatley's v 1.3 of Paul Nankervis's ODS2 at
> .  This program
> "Sector 1 read failed 87
> PHYIO Error 500 Block 1 Length 512 (ASPI: 0 0 0)
> Mount failed with 500"
> Chuck G., does anyone know...
> 1. What that error means?
so far, only that it failed on what was probably the first sector that it 
tried.   "87" is probably not meningful to anybody except VMS
"PHYIO"  MIGHT mean physical I/O
"500" also isn't applicable to other systems.

> 2. If it would make a difference that I'm 
> running the Win32 exe in Windows 98, rather than NT, 2000, XP etc.?

It is more likely to be successful in 98 ("real mode")

> 3. I'm not sure ODS2 was built with 8 inch disks in mind?
No idea.  But, other than NEC PC98, machines generally do NOT use the same 
format specs on 8:, 5.25, 3.5

> Would it make a difference?
If there are more than one format available, then the read program might 
1) ASSUME one of the lot
2) have options to choose
3) attempt to detect what it sees.
Besides ODS-2, what about ODS-1 and ODS-5?
Find somebody who knows VMS, and find out what the options were.

> CP/M disks in the 8 inch drive can be accessed and read/written to under 
> MS-DOS by the machine I have the drive hooked up to, so I don't think 
> it's a hardware issue.
Does your system handle single density?  (some FDCs do; some don't)

> 4. How likely is it that disks from a 1985 VAX is in some weird 
> proprietary format OTHER than VMS?

quite possible.  For example, they might have, at some point in the past, 
used a program under VMS to copy their data to some other format that they 
thought might be handy, such as SSSD CP/M!

Using IMD, or other tools, can you determine the density, bytes per 
sector, and sectors per track of the disks (try at least 2)
Also, is the data recorded single sided, or both sides?

If you can read it with IMD, then you can start wading through content 
within sectors to get more clues about what's there.

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