Re: LDOS or XENIX wanted for the 16 ,6000 (long)

Homer J Simpson <nobody@xxxxxxxxxxx> wrote:
: The trick seems to be to use a 1.44 Mb floppy drive in place of the 8"
: floppy.

Because of its 300RPM rotational speed, the 3 1/2" drive is not the best
choice for replacing an 8" drive as a boot device, and it would be tricky
to make a Model II/12/16/16B/6000 boot from one. You would have to come
up with a diskette formatter willing to lay a 3740 disk format on
cylinder 0 head 0 with a pattern almost 2K longer than normal. It will
also confuse any drive diagnostics expecting 6pps on the index signal,
not 5. This might trigger a BOOT ERROR DC or similar message.

See:
http://nemesis.lonestar.org/computers/tandy/hardware/model16_6000/floppyfix.html

for details on connecting 5 1/4" HD drives to places where 8" drives
were before. Both have 360 RPM speeds and identical data clock rates
so apart from some pin-out issues, they can be made compatible.


Track 0 on 8", 5 1/4" and 3 1/2" media is on the inner-most part of the
media. This is also the case with MFM hard disk drives, LaserDiscs, CDs and
DVDs. Most post-MFM hard disk drives also have track 0 nearest the spindle,
but some drives now place the lowest logical tracks elsewhere for better
performance.

8" drives (particularly the slim line models) are notorious for
destroying media, scraping furrows on both sides so you can see through
the media. All you have to have is a tiny deposit on either head,
and the destruction is usually immediate. Worse, the Tandons head 1
mounting is so fragile that most people who try to clean them manually
bend or break the mounting wires, so now the drive destroys media
instantly, regardless of any dirt on the media. Tandon thinline drives
were used by Tandy in the Model 16/12/6000/6000HD models. They are bad.
poor quality drives, even by the standards of 1982.

Older media adds to the problem by easily yielding a layer of the
media plus any accumulated dust when the head makes contact. Some media
has a gummy/sticky undercoating that can come up in tiny amounts, but
this is more than enough to get the heads grinding away at the remainder
of the media. Some vendors claim to have put a small amount of lubricant
in their media, but chances are it has largely evaporated by now or
has attracted and collected some dirt, making it far from lubricating
today.

I have several cases of 8" media I have been slowly trying to salvage
and migrate the contents onto more stable media. (Some of it is
almost 30 years old.)

Step 1 is always to take an image of the media to stable media
(usually 5 1/4" or direct to hard disk image file), without doing any
filesystem seeks/searches. Load it, Read it, and get it out of the
drive immediately. Clean with cleaning discs, UNLESS it is a
single-sided drive that can be safely cleaned by hand.

I now have about four drives I cycle though (down from 10 when I
started), cleaning frequently and avoiding touching any side 1 head
with anything other than the cleaning disc. Soon I will have to
go to the junk computer stores and scrape up some more 8" drives
to use in this endeavor.

I recommend finding and using an old single-sided drives for recovering
single-sided media. A lot of the damage on these discs is caused by the
side 1 head tearing up the side with no content, but the damage it is
doing can contort the media and initiate problems on the other side.
It is much safer to just have the felt pad on side 1 if there is no data
over there.

All Tandy 8" distribution media was single sided except for two XENIX
software releases. Even after double-sided was all Tandy shipped,
software was distributed on single-sided media anyway so that the
stores would not have to stock two types. So, most of the data on
double-sided media will be customer-created data.


3M (I think that was the vendor) used to recommend cleaning long archived
media prior to insertion when doing content transfers. You will need:

o Full-sized pair of scissors, not the kiddie-round tipped ones, a sharp
pair you can cut a straight line with.
o Fine point sharpie permanent marker.
o Flat smooth working surface.
o Diskette labels.
o Soft, dry, Lint-free cloths
o Silk gloves (like they use for working with photograph negatives)
o Clean sheets of paper at least 10x10 in size, preferably glossy/slick
o Compressed air (NO OIL!!!)

Start by taking a sharpie permanent marker and writing a SMALL "L" or
some other mark on the media itself right up against the center hole on
the label side of the diskette. (You'll need this mark later.) Now take
the diskette and with your thumb through the drive hole in the middle,
shift the magnetic media to one side, and using scissors, cut open the
opposite end of the diskette sleeve (just one side), cutting no more than
1/8" in from the edge. The narrower the amount of material cut, the
better. (I've heard of people using a table top paper cutter, but I
suspect this takes some practice to get right, and being careful to
not crush/bend the media inside.)

Wearing silk gloves and as gently as possible, use your thumb (sticking
through through the center hole) to start sliding the media out of the
sleeve and onto a very clean, very flat surface, such as a piece of
glossy paper or several sheets of stacked glossy paper. (Do not do this
using a wood table or any other surface with a non-smooth texture.)
Grasp the media and pull it the rest of the way out the sleeve.

Using compressed air or by blowing, blow any visibly loose material
off both sides of the media. Watch for debris landing on the working
surface and clean those away too.

If the media shows marks of being stained by liquids, you may need to run
plain water across the media and allow it to thoroughly dry (at least
a few hours) before proceeding. (For drying, you can suspend it on a
piece of non-magnetic wire through the center drive hole.) DO NOT RUB
MEDIA WHILE WET OR DRYING!

Don't let the diskette sleeve interior get wet. If it is contaminated,
find a donor sleeve from another diskette and use it rather than try to
clean a dirty one. If you persist in wanting to get the desired sleeve
wet, let it dry in the sun for days (maybe even a week or more) so that
there is no moisture left at all. You don't want any moisture migrating
out of the sleeve corners once the media starts spinning.

With the media laying flat on the clean, smooth surface, use a clean,
lint-free soft cloth, and gently rub the media. Rub across the media
rather in line with the media, pulling the cloth towards you, avoiding
the urge to hurry or push. Make as many small strokes as needed
rather than trying to wipe the media with three or four big strokes.
Do not let the media bunch or fold, because this will leave permanent
bends in the media, rendering it unreadable. Inspect/turn the
cloth frequently. Repeat on the opposite side of the media, making
sure that the working surface is still clean and has no foreign matter
that could create dimples in the media.

If the media was single-sided, clean the side you marked first, which
has no data. Then clean the opposite side, side 0. On double-sided
media, it doesn't matter which you clean first, but do both sides.

Don't rub hard, as you will always get more "dirt" off the media.
You just want to get any loose or foreign material off the surface
that the heads could run into. Rubbing hard can burn a hole right
through the coating or cause the underlying binder to disintegrate.

Once finished, spray compressed air (if available) into the diskette
sleeve, away from the cleaned media. Shake out any heavier objects,
like dead insect parts. Now, carefully re-insert the media into
the sleeve, noting the mark you put on the media earlier to show
you which way is the label side. This can take a bit of practice,
as you must be sure not to snag, fold or scratch the media while
getting it back inside.

Once the media is back inside diskette, you can use a diskette label to
seal the open edge of the diskette sleeve. (The diskette vendor
suggested write-protect stickers, but I found these fell off quickly,
particularly on 8" media, and sometimes ended up in the drive works.)

I suggest practicing on at least one diskette you have already made
a copy of before moving to the ones with one-of-a-kind data on them.

Doing this to a diskette isn't a good idea if you plan to put the same
diskette back into storage or try to use it regularly. It is mainly
intended as a way to give you the best shot at recovering the full
contents from old media in order to make a new replacement diskette,
discarding the older diskette (or cease using it) when complete.


Frank Durda IV - only this address works:|"What I'm after is one of those
<uhclemLOSE.nov05%nemesis.lonestar.org> | voting systems where you get
You must remove the "LOSE" to mail me. | to directly punish politicians
http://nemesis.lonestar.org | via each vote for or against
Copr. 2005, ask before reprinting. | something they propose."

.

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