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DMF Format

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evildragon

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I tried using a DMF formatted floppy on my Model 25 (using the 1.44MB floppy I bought from IBMMuseum), and while I can list the directory contents, 97% of the time, trying to copy a file results in a Track 0 Invalid error..

Isn't DMF supposed to work on all HD floppy drives?

(This is just an experiment for a technical college project... Doesn't need to work if it cant, always got the drive with my laptop which I can use.. It's just that I'm now curious as to this)..
 
evildragon said:
I tried using a DMF formatted floppy on my Model 25 (using the 1.44MB floppy I bought from IBMMuseum), and while I can list the directory contents, 97% of the time, trying to copy a file results in a Track 0 Invalid error..

Isn't DMF supposed to work on all HD floppy drives?

(This is just an experiment for a technical college project... Doesn't need to work if it cant, always got the drive with my laptop which I can use.. It's just that I'm now curious as to this)..
Click to expand...

I tested the drive (booting to MS-DOS 6 on it, and thought I did copying to & from), in fact went through checking a few before I shipped it out. The drives do go bad, which was the reason I tested it. If repeatable with a few different floppies we can talk over replacement actions.
 
IBMMuseum said:
I tested the drive (booting to MS-DOS 6 on it, and thought I did copying to & from), in fact went through checking a few before I shipped it out. The drives do go bad, which was the reason I tested it. If repeatable with a few different floppies we can talk over replacement actions.
Click to expand...
Oh, the drive works great, I can read DD, and HD disks with no issue at all.. (i might not have been clear in my original post)

But if a disk is DMF formatted (1.68MB), it has troubles with them. I don't know if it's because of the way the tracks are positioned, or if they are smaller and harder to read...
 
What operating system are you trying to read the DMF disks in? MS-DOS 6.x doesn't read DMF disks. You need to be in at least Windows 9x to be able to read files off of DMF disks, or if in DOS, you'll need to run a BIOS extender such as FDREAD (comes in the excellent FDFORMAT package, usually found as FDFORM18.ZIP) or the extender that comes with 2m.
 
I was indeed using DOS 6.22...

But, if you need windows 9x to read a DMF floppy, how did the Windows 95 Floppy Installation pack work? ;) You were in DOS then, so the disk had to have been read.
 
evildragon said:
I was indeed using DOS 6.22...

But, if you need windows 9x to read a DMF floppy, how did the Windows 95 Floppy Installation pack work? ;) You were in DOS then, so the disk had to have been read.
Click to expand...

Win9x DOS was a later-than-6.22 DOS, so it may have the DMF driver already built-in.

Who knows? It IS Microsoft, after all ;)


T
 
Sharkonwheels said:
Win9x DOS was a later-than-6.22 DOS, so it may have the DMF driver already built-in.

Who knows? It IS Microsoft, after all ;)


T
Click to expand...
I'm talking about when you had DOS 6.22 or windows 3.11 and were JUST making the move to Windows 95.. You were still in at best DOS 6.22 and had to read those DMF floppies ;)
 
With a Win95 floppy installation, the first disk in the set is a 1.44 meg. floppy. All the rest are DMF format. The first disk loads the proper driver, then all the rest of the floppies are readable.
 
Problem is, if you booted off that floppy #1, it may be in the kernel.
Or, if you were on 6.22 and just ran setup.exe, the DMF code may be in the installer itself (setup.exe)

What is it you're trying to do exactly?
Can you give us more detail so we can maybe find a workaround?


Tony
 
Sharkonwheels said:
Problem is, if you booted off that floppy #1, it may be in the kernel.
Or, if you were on 6.22 and just ran setup.exe, the DMF code may be in the installer itself (setup.exe)

What is it you're trying to do exactly?
Can you give us more detail so we can maybe find a workaround?


Tony
Click to expand...
for my college, the project was to see how much data could be fit on a floppy (just alternating 1's and 0's), with different formats.. DMF was one that I liked the idea of, but couldn't get to work..

another one was, skipping "formats", and doing direct access to the hardware, and just trying to cram as much binary as we can.. That of which I haven't even tried yet..
 
evildragon said:
for my college, the project was to see how much data could be fit on a floppy (just alternating 1's and 0's), with different formats.. DMF was one that I liked the idea of, but couldn't get to work..

another one was, skipping "formats", and doing direct access to the hardware, and just trying to cram as much binary as we can.. That of which I haven't even tried yet..
Click to expand...

Does your project include the overhead of whether actual data is being stored? If not, the latter idea you presented can be easily achieved using the Linux 'dd' utility. The disks themselves are actually around 2MB raw. Even without formatting, though, you can't store and retrieve data using alternating 1's and 0's. -you still have the overhead of separating individual patterns of data that represent something, not to mention that long strings of the same bit tend to induce their own problems (how many 0's was that again? Been so long, I forgot...).

When Windows95 first came out, 'WinImage' was one of the most often used utilities that would let you reformat floppies in DMF, in either DMF variation of 1024 or 2048 clusters. While trying to make backups of my install disks, I found that perhaps only 1/2 to 1/4 of the floppies I tried of various brands, from white box to premium, could be formatted as DMF, having only been certified for 1.44MB...
 
No, no data will actually be stored, well, not in a filesystem sense..

I know they can hit about 2MB, as that's what some of my older HD disks say right on them.. The idea however, is to use all 2MB, for use.

The proposal: Instead of using a filesystem, make it be more like how an EEPROM works.. You write the data once, and you can retrive what you want, using a special utility to retrieve data.. if you want to write new data, you'd have to write the whole disk again, just like an EEPROM..

That's sorta how I plan to do this.. And with the model 25, it seems accessing the disk directly is a LOT easier than using my laptop, with Windows in the way all the time..
 
I just double-checked my Win95 floppies; it is a 13 disk set and yes, the first disk is 1.44 meg. format, the rest are DMF.

The DMF driver is probably in the setup.exe file.
 
RAW storage

RAW storage

evildragon said:
No, no data will actually be stored, well, not in a filesystem sense..

I know they can hit about 2MB, as that's what some of my older HD disks say right on them.. The idea however, is to use all 2MB, for use.

The proposal: Instead of using a filesystem, make it be more like how an EEPROM works.. You write the data once, and you can retrive what you want, using a special utility to retrieve data.. if you want to write new data, you'd have to write the whole disk again, just like an EEPROM..

That's sorta how I plan to do this.. And with the model 25, it seems accessing the disk directly is a LOT easier than using my laptop, with Windows in the way all the time..
Click to expand...


A BIOS EEPROM is pretty much a single file; a single stream of bytes, read according to an offset. That same concept is used by an operating system for executables and library files, but with an added layer of abstraction.

That's similar to what SQL Server does with what are known as 'RAW' volumes; a partition is created on a drive array but no file system written to it. SQL Server then grabs the entire partition and uses it as a single file, keeping all housekeeping info internal to the database that is written to the RAW volume. Only a 1-2 % performance gain, but just about all the space that is normally 'wasted' by file system formatting is then usable for data storage. However, the whole 'file' does not have to be rewritten; being really good at keeping track of things, as it is a database engine, it only rewrites small chunks or pages as needed.

To get this discussion back onto a vintage computing slant before some yahoo says, "Hey, this is a vintage computer forum; go find a modern PC hacking website" ;-) ...You might find some interesting insight if you research the evolution of accessing long term storage and/or filesystem evolution, as you are walking the same path...the next step in the evolution was to store a program and it's data on the same medium, then *two* totally unconnected files on the same medium...must be some fascinating stories out there, considering the early medium may have been tubes or tape....
 
yea, treating the floppy as a single large file, but with a structure, like a ZIP file (or .cab) ;)

As for vintage DMF format, I will hunt down that driver on my win95 floppy, when i find that floppy..
 
Trixter said:
That's why you look in the .zip file just one second longer to find FDR88.COM which *will* work on an 8088.
Click to expand...
Well I didn't see it. Which btw, it's a .exe, not a .com..

EDIT: It worked. Thanks to those who suggested it.
 
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