80% maximum capacity on a hard drive?

[Rod Speed]

Coming from a man who's the life and soul of any party!

Hi, Folkert. Nice break?

Even the pseudokrauts give their loonys the bums
rush out of their padded cells occasionally now.

Much cheaper than keeping them in padded cells now.

 

[Alexander Grigoriev]

I *very* doubt the heads would fly over helium.

 

[Bob Willard]

I *very* doubt the heads would fly over helium.

Well, you are wrong. Note that the disk was not a standard disk
with helium just replacing the standard air; the HDA was designed
from scratch with helium as the intended environment. And yes, the
heads flew: all of them (head-per-track, for the ultimate in low
seek time).

 

[Horst Franke]

In Alexander
Grigoriev typed:

I *very* doubt the heads would fly over helium.

Hi Bob, I agree to Alex,
on those days I only know HD heads flying on pure air.
Horst

 

[Bob Willard]

In Alexander
Grigoriev typed:



Hi Bob, I agree to Alex,
on those days I only know HD heads flying on pure air.
Horst

In the 60's and 70's, DDC (Digital Development Corporation) made a series
of head-per-track disks with the entire HDA enclosed in a sealed helium
environment. DDC was a San Diego company, no longer in business AFAICT.

Those low capacity, high cost, units were most definitely not commodity
products. We used them because the reliability of standard HDs of the
period ("rust" sprayed on metal platters) was inadequate, particularly
in the somewhat corrosive environment of paper and chemical plants.

 

[Arno Wagner]

Horst Franke wrote:

In the 60's and 70's, DDC (Digital Development Corporation) made a series
of head-per-track disks with the entire HDA enclosed in a sealed helium
environment. DDC was a San Diego company, no longer in business AFAICT.

Were these about 1.5m long and maybe 1m x 1m large drum-type
storage devices? If so there is one on display in my old university.
Impressive technology, of a bit bulky.

Those low capacity, high cost, units were most definitely not commodity
products. We used them because the reliability of standard HDs of the
period ("rust" sprayed on metal platters)
;-)=)

was inadequate, particularly
in the somewhat corrosive environment of paper and chemical plants.

Not surprising.

Arno

 

[dew]

Were these about 1.5m long and maybe
1m x 1m large drum-type storage devices?

The head per track disk that I had went in a standard
DEC rack, about 9" high from memory. RS09

Doubt it was helium filled.

If so there is one on display in my old university.
Impressive technology, of a bit bulky.

Sounds like a drum not a disk.

 

[Bob Willard]

Were these about 1.5m long and maybe 1m x 1m large drum-type
storage devices? If so there is one on display in my old university.
Impressive technology, of a bit bulky.

The entire device was designed for 19" relay rack mounting, on slides.
The slides attached to a thick (~1" aluminum?) base plate, with the HDA
can above the base plate. Inside the can (~18" diameter and ~14" high):
the platters, R/W heads, pre-amps, and two He pumps. Below the base
plate: a card cage of electronics, a He bottle, and a check valve; the
check valve allowed the He bottle to be replaced while the disk was in
operation -- without stopping/disturbing the OS. (He atoms are rather
small, and will leak through solid Cu tubing, even if the plumbing is
properly done.)

One He pump maintained positive pressure inside the can -- better to have
He leak to the outside than to allow mildly corrosive air to leak to the
inside and play etch-a-sketch on the platters. The other He pump was
activated when the platters were up to speed to force the heads to fly
close to the platters; upon power down, this He pump stopped, allowing
springs to force the heads away and guarantee non-contact start-stop.

Since I haven't seen one in ~30 years, I have undoubtedly forgotten a
few details. In the '68-'71 time frame, I spent a lot of my life with
that thing: I created/negotiated the specs for one variant, helped to
debug/redesign the electronics at DDC, architected the Fox-1 system
(including the I/O system) that used it, and wasted a lot of He while
learning the art of plumbing.

 

[Folkert Rienstra]

no longer in business AFAICT.

What still is.

Man, this brings back memories.
PDP-8s, 8i, toggleswitch data panels, flipchip modules in wirewrap backplanes,
core memory, papertape readers, teletypes, Vermont drums, Magtape etc. Drums
later replaced with Ampex Megastore core memory disks. Now those were the days.

Were these about 1.5m long and maybe 1m x 1m large drum-type
storage devices? If so there is one on display in my old university.

Impressive technology, if a bit bulky.

You should have seen the core memorie modules that went in the Megastores.
You needed two hands (just to lift them, that is).

Or a steel mill.

 

[RonTaylor]

Sorry, I know this a very very old post/topic but.. I was just googling for info on the DDC Helium filled drives and ran across this. There seems to me to be some confusion as to if these exsisted or not and if they would even work.

I can tell you first hand that the DDC helium fill drives with flying head worked and worked well.
I was a field engineer for a company in Houston that designed and fielded a seismic data acquisition system using a DEC PDP 11/20 and these DDC drives, Pertec Transports and such. Our first ones shipped to Algeria in about 1971. When we would start having disk errors, the first thing to do was to purge the drives with 'atomic grade' helium (yes thats what the cylinders said on them and I still have two empty ones!). Since these were mounted in trucks, when you shut the system down, you have to wait for the drives to spin down to eliminate them tearing themselves up before moving to another shot location. Large rack mounted with a big blue round cover! Never forget them. Plus monster Onan generators to run it all (110vac 60hz in the Sahara!!! LOL)