DOS ain't dead - system~1 RESTO~1: Delete Them?

CluelessInSeattl

Seattle, USA,
17.01.2013, 17:44

system~1 RESTO~1: Delete Them? (Users)

I'm cleaning up and backing up the hard drive in my hand-me-down Toshiba Satellite 2545XCDT laptop on which I'm running MS-DOS 6.21.

I'm backing up essential files prior to reformatting and repartitioning the hard drive. (It turned out that a couple of my legacy DOS programs can't handle partitions larger than 1 GB).

Working my way through the directories on the HD, I came across a weird directory that looks like it was created by a back-up utility about a year ago. (Due to chronic disabling health issues my memory is failing me these days and I have no recollection of creating these directories or files)

If you have ever worked in MS-DOS, can you tell me if these directory or file names ring any bells:

system~1 [Directory: No files]
RESTO~1 [Sub-directory: No files]
RP97 [Sub-sub-directory: 625 Files]

That last directory contains 625 files with names like:

A0007069.COM
A0007103.EXE
ETC....

My first impulse is to just to delete the whole works.

Any ideas on how to identify which program created these files, and how to figure out the names of those 625 files in that last sub-directory?

The fact that two of these directories have the ~# tags at the ends of their names would seem to indicate that the directories were created by one of the versions of Windows that had the so-called long filename (lfn)capability.

But I don't think I've ever run Windows on that litle laptop. Only MS-DOS. However, it is a hand-me-down laptop, and probably had some version or other of Windows on it when I received it. But as I recollect, the first thing I did when I received the laptop was to reformat and repartition the hard drive and then install MS-DOS 6.21.

---
Will in Seattle
a.k.a. "Clueless"
Running MS-DOS 6.21

Zyzzle 17.01.2013, 23:26 @ CluelessInSeattl	system~1 RESTO~1: Delete Them? Post reply
	Seems to be remnants of some Windows repair utility / backup utility. Possibly an undelete program, like Recover4all created these files. I think you may safely delete the files. The fact that they are in an lfn directory points to the fact that DOS did not create them and will not use them.

Rugxulo

Usono,
18.01.2013, 18:09

@ CluelessInSeattl

system~1 RESTO~1: Delete Them?

Post reply

> That last directory contains 625 files with names like:
>
> A0007069.COM
> A0007103.EXE
> ETC....
>
> My first impulse is to just to delete the whole works.

"Probably" a good impulse, but I can't say with certainty.

Though .COM is DOS only, but is it less than 64 kb? It could just be a renamed .EXE file (which will still run). Are the .EXE files PE (Windows) or for native DOS? Obviously if it's PE (which 99% of the time means no useful DOS stub), you can delete with impunity. A quick check of the EXE header should show which is the case. In fact, it might even be beneficial to check (via "strings" util or hex editor or similar) inside various files there, just to be sure.

CluelessInSeattl

Seattle, USA,
20.01.2013, 15:46

@ Rugxulo

system~1 RESTO~1: Delete Them?

Post reply

> A quick check of the EXE
> header should show which is the case.

"EXE header"?

That's a new one on me. What is that? And how do I display it?

BTW, I did look at one of the .BAT files in the directory, and it turned out to be one that I myself had written. And identical to one in my current batch file directory.

So my guess is that these mystery directories and files were created by some kind of backup and restore utility that I've completely forgotten about. (Nothing new there. Many times a day these days I walk into a room to get something and haven't a clue what I went in there to get. Ah! the viscititudes of aging, eh?)

So, I just held my breath and deleted the whole works. I hope I don't regret it.

---
Will in Seattle
a.k.a. "Clueless"
Running MS-DOS 6.21

Arjay

20.01.2013, 19:49
(edited by Arjay, 20.01.2013, 23:53)

@ CluelessInSeattl

system~1 RESTO~1: Delete Them? EXE headers

Post reply

> > A quick check of the EXE
> > header should show which is the case.

> "EXE header"?
> That's a new one on me. What is that? And how do I display it?
.COM files can only be up to 65,280 bytes in size and had no header. To support larger executable files one of the core DOS developers at Microsoft was tasked with coming up with a new file relocable format which had a header.

The developer was Mark Zbikowski and what he came up with is of course the .EXE file format. The first 2 bytes of all EXE files contain Mark's initials which is how various software determines if the file is an EXE or NOT. e.g. Does the first 2 bytes of the file consist of "MZ" or "ZM" which is also valid. You will need a hex editor to view the files such as Hiew 6.50 for DOS including reviewing the EXE header itself.

Additional trivia: Mark also designed DOS's MCB (Memory Control Block) used for memory management hence why M is used as a marker for items within the linked list and Z on the terminator on the last item. Windows 95 also used his initials as parameters on WIN.COM and elsewhere...

> So, I just held my breath and deleted the whole works. I hope I don't
> regret it.
You should be fine.

bocke

20.01.2013, 22:32

@ Arjay

system~1 RESTO~1: Delete Them? EXE headers

Post reply

> The developer was Mark
> Zbikowski and what he came up with is of course the
> .EXE file
> format. The first 2 bytes of all EXE files contain Mark's initials which
> is how various software determines if the file is an EXE or NOT. e.g. Does
> the first 2 bytes of the file consist of "MZ" or "ZM" which is also valid.

Thanx for the interesting bit of history. I didn't know that MZ stood for M. Zbikowski. :)

Arjay

21.01.2013, 00:10

@ bocke

system~1 RESTO~1: Delete Them? EXE headers

Post reply

> Thanx for the interesting bit of history. I didn't know that MZ stood for
> M. Zbikowski. :)
:) The use of his initials on MCB's are documented somewhere but I could find a ref easily online so I probably learnt that fact from one of my books. When first working with Win95 I remember realising that there had been a continued tradition of carrying on using his initials elsewhere either by Mark or others. Mark left Microsoft on Friday 9th June 2006. There is a interview with him but I haven't watched it.

If you like learning about the history of how DOS, Windows has evolved then Raymond Chen's blog Oldnewthing is often interesting, e.g. the posts Why does a corrupted binary sometimes result in "Program too big to fit in memory"? What's the difference between the COM and EXE extensions? are relevant to this particular thread.

[EDIT] - In the what's the difference post Raymond may give the casual reader the impression that a .COM program can't start with MZ when I can assure you that it can but that presents problems under many situations unsuprisingly....