I have a local buddy who has a dying 30M hard drive on some kind of
Atari which he says is in a rather big box (for an Atari). It is MFM
and he wants me to sell him one of my extra PC MFM drives if we can
figure out how to make it work. Anybody know how to go about that?
Also I have an Atari 540ST, and I suppose I might like to use a HD with
that, if it's not too hard or expensive. Anybody know where I can get a
controller for it cheap?
Below is my email to the guy attempting to explain why it might need to
be low-level formatted. I'd welcome any comments on any of that as well,
or we could even get into a discussion about various FS architectures
if there are any experts here on that....
> > > My Atari is 30MByte. If you can low-level format one for me or if you
> > > think I can use a 40MByte,
> > > that's Okay too. Please let me know if you have any luck.
> >
> > There's gotta be some Atari software or firmware for doing the low-level format.
>
> I have a program called HDX which lets me format for both The
> Standard Atari and for my alternate OS-9 system.
>
> I guess I mis-understood what you meant at the Linux meeting
> about having to format the old drive before I could use it.
> I really don't know the difference between low and high formatting.
As I understand it, low-level formatting means it writes the timing marks.
MFM drives usually use one side of one platter just for these marks
that tell the electronics where the heads are at, at any given point.
So by rewriting these marks, you can change the "architecture" of the
drive, specifically, how many sectors per track. I was told that each
brand of hd controller does its own style of formatting, but I'm not
really sure what the differences are, just that the chances are very
good that when you move a drive from one machine to another, the hd
controller won't be able to use the formatting on the drive as-is.
By contrast, IDE (Integrated Drive Electronics) puts all the proprietary
stuff on the drive itself, and the data going over the cable to the drive
conforms to the standard. So you usually can't low-level format an IDE
drive (and attempting to do so with one of those 286 BIOS's that can do that
has been known to render IDE drives unusable), but some manufacturers
will provide the software to do it. Usually it's done at the factory
and never needs to be done again.
On a PC, if you need to low-level format an MFM drive there are several
options. Starting with the original XT controller, IBM set the standard
that BIOS code for doing that formatting would always start at a particular
address. So, you could use DOS's debug utility to simply execute the
code starting at that ROM address, and it would prompt you for the
parameters of the drive (number of tracks, number of heads, sectors
per track, etc.) and then do the format. But AT clone BIOS's typically
had a nice menu-driven program accessible from the "CMOS setup" routine
to make this easier. So I can only assume that Atari's have a similar
capability, either in the HD controller ROM, or the main BIOS, or some
program that you have to run. You can check to see if your HDX makes that
distinction; chances are if it doesn't, it's only doing the high-level
formatting. (They would have no doubt preferred that you buy your HD
pre-low-level-formatted from them, anyway.) Or, maybe the Atari uses
a common PC-style controller chip, in which case if the drive was formatted
on a PC with that same controller chip, I imagine it would work on the
Atari as well.
High-level formatting simply means constructing the filesystem. Given
a reliable set of tracks with certain-sized sectors, how do we organize
them into clusters, and then how do we put a file onto the disk, and keep
track of where it is located. I believe on both DOS and Unix file systems,
files are linked lists; the filesystem code can find out on what track
and sector the file starts, and it can then read the first block, but
the last few bytes of the first block are a "pointer" saying where to
continue reading next. But with Unix filesystems, the information about
where to start reading a file is distributed, whereas a FAT filesystem
puts all the information about all the files on the first few tracks
(the File Allocation Table). The FAT is a list of files, names, sizes,
permissions, etc. along with where each file starts - sort of a flat
database. The reason FAT formatting has limits as to how much data can
be stored, is that you can run out of room to create more entries,
so it won't matter whether or not you can write more data, because you
can't index it, therefore can't find it later on. But I don't know as
much about Unix filesystems, and nothing at all about Atari's.
>
> SO, do you think you have something I could buy that might get my
> atari back up and running? I've been told that the surface of my
> current drive is possibly too sticky but it sure looks clean.
> I've been having to tap the side of the case for over a year to
> get the darn thing to come up to speed but that tap no longer is
> enough, it seems.
>
> *****
> I gave up on my friend's XT because his 1.4 floppy card had 6
> jumpers and no documents or hints on the card to tell what any
> of the jumpers meant. Thanks for 286 offer but I don't want to
> fool around with his system to that extent. He needs to cough up
> about $500 for a Win95 system of some sort for his wife to use for
> the purpose of training to become modern enough to be an office
> receptionist. It's hell getting old and having technology pass one
> by.
It's also optional, don't you think?
--
_______ KB7PWD _at_ KC7Y.AZ.US.NOAM ecloud_at_goodnet.com
(_ | |_) Shawn T. Rutledge on the web: http://www.goodnet.com/~ecloud
__) | | \__________________________________________________________________
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Received on Tue Jun 02 1998 - 16:22:47 BST