20 Apr
2018
20 Apr
'18
10:45 p.m.
From: Warner Losh
Drum memory stopped being a new thing in the early
70's.
Mid 60's. Fixed-head disks replaced them - same basic concept, same amount of
bits, less physical volume. Those lasted until the late 70's - early PDP-11
Unixes have drivers for the RF11 and RS0x fixed-head disks.
The 'fire-hose' drum on the GE 645 Multics was the last one I've heard
of. Amusing story about it here:
http://www.multicians.org/low-bottle-pressure.html
Although reading it, it may not have been (physically) a drum.
There never was a drum device, at least a commercial,
non-lab
experiment, for the VAXen. They all swapped to spinning disks by then.
s/spinning/non-fixed-head/.
Noel
20 Apr
20 Apr
10:53 p.m.
New subject: /dev/drum
On Fri, Apr 20, 2018 at 9:45 AM, Noel Chiappa <jnc(a)mercury.lcs.mit.edu>
wrote:
Correct; it was a fixed head disk; nicknamed firehose for the high data
rate. I am not sure if this is the exact model number, but it was a
Librafile device:
https://archive.org/stream/TNM_Librafile_3800_mass_memory_from_Librascope_-…
-- Charles
From: Warner
Losh
Drum memory stopped being a new thing in the
early 70's.
Mid 60's. Fixed-head disks replaced them - same basic concept, same amount
of
bits, less physical volume. Those lasted until the late 70's - early PDP-11
Unixes have drivers for the RF11 and RS0x fixed-head disks.
The 'fire-hose' drum on the GE 645 Multics was the last one I've heard
of. Amusing story about it here:
http://www.multicians.org/low-bottle-pressure.html
Although reading it, it may not have been (physically) a drum.
11:16 p.m.
New subject: /dev/drum
Noel Chiappa wrote:
Just a note... back in my old DEC days I went around and installed a
thing called the ML11-A (IIRC).
It was a Massbus box of MK11/MS750 memory arrays interfaced to a disk
emulation controller.
Plug it on your Massbus, format the memory with the disk formatter and
you have something like
an RS04 swap device made out of memory with no rotation delay. Consider
it an early SSD.
It used plain old PDP/VAX memory (and could format and bad block out ECC
errors so the memory
didn't have to be perfect) and was software compatible (I think) with
the RS04...
I installed one at the AT&T/NY Bell site next door to the World Trade
Center back in 84-85 or so.
I wonder if it was still running on 9/11. Word was Unix really was
improved on the 11/70 boxes without a huge investment on new gear.
Quick swap was a big help on heavily loaded boxes.
Loved seeing the diag run tests and light the fault light on the box of
memory. Also had a write protect like every good drive should.
Bill
--
Digital had it then. Don't you wish you could buy it now!
pechter-at-gmail.com http://xkcd.com/705/
From: Warner
Losh
Drum memory stopped being a new thing in the
early 70's.
Mid 60's. Fixed-head disks replaced them - same basic concept, same amount of
bits, less physical volume. Those lasted until the late 70's - early PDP-11
Unixes have drivers for the RF11 and RS0x fixed-head disks.
The 'fire-hose' drum on the GE 645 Multics was the last one I've heard
of. Amusing story about it here:
http://www.multicians.org/low-bottle-pressure.html
Although reading it, it may not have been (physically) a drum.
There never was a drum device, at least a
commercial, non-lab
experiment, for the VAXen. They all swapped to spinning disks by then.
s/spinning/non-fixed-head/.
Noe 
21 Apr
21 Apr
5:35 a.m.
New subject: /dev/drum
On Fri, 20 Apr 2018, William Pechter wrote:
Also had a write protect like every good drive should.
Not only that, but I note that my Mac does not have a visible
disk-activity indicator; not surprising, really, as it seems to be
thrashing like hell whenever I have the temerity to focus (i.e. click)
upon another window.
Now, my Mac's system disk is external (don't ask), and it has a barely
visible blue LED, which is why I know when it thrashes sometimes. I
intend to throw together a photo-transistor and a high-efficiency LED
(plus a 9v battery) for a more visible "Danger! Will Robinson!" alert.
--
Dave Horsfall DTM (VK2KFU) "Those who don't understand security will
suffer."
22 Apr
22 Apr
5:48 p.m.
New subject: /dev/drum
i remember the interdata i started my unix career on. it had a halt light which was a good
indication of cpu inactivity. we planned (though never did) to attach a light dependant
resistor a big cap and an old brass meter in a wood and glass case so we could have a
measure of “bored” to “thrashed” in true frankinstien’s lab style.
happy days
-Steve
On 21 Apr 2018, at 00:35, Dave Horsfall
<dave(a)horsfall.org> wrote:
On Fri, 20 Apr 2018, William Pechter wrote:
Also had a write protect like every good drive should.
Not only that, but I note that my Mac does not have a visible disk-activity indicator;
not surprising, really, as it seems to be thrashing like hell whenever I have the temerity
to focus (i.e. click) upon another window.
Now, my Mac's system disk is external (don't ask), and it has a barely visible
blue LED, which is why I know when it thrashes sometimes. I intend to throw together a
photo-transistor and a high-efficiency LED (plus a 9v battery) for a more visible
"Danger! Will Robinson!" alert.
--
Dave Horsfall DTM (VK2KFU) "Those who don't understand security will
suffer."
2436
days inactive
2438
days old
4 comments
5 participants
participants (5)
-
Charles Anthony -
Dave Horsfall -
jnc＠mercury.lcs.mit.edu -
Steve Simon -
William Pechter