Memory

In article o.uk, Dave
Liquorice scribeth thus
On Mon, 28 Apr 2014 01:40:04 +0100, Johny B Good wrote:

I regard not only CD as pre-historic but DVD and Blu-Ray[1] too. It's
not that that makes me feel old, just the effects of old age creeping
up on me.

Presumably old age is having its normal affect on hearing and sight
so you don't notice how crap downloads and/or streaming are compared
to CD or Blu-Ray (or even DVD come to that). B-)


I think I find them more objectionable as time goes on Dave!...
--
Tony Sayer

Stephen wrote:

My estimate would be 30 minutes at 3 3/4 inches per second, mono, 10 kHz
frequency response, signal to noise ratio 40dB.

My little tape recorder had a non-standard speed of 4ips and also had
the tape wound in a funny way so it played backwards on a normal
machine. For tapes I used to strip down 1/2" computer tape. My uncle
worked at IBM and he used to get it for me.

Bill

I see, make a career of misreading then? Who is she?

Brian

--
From the Bed of Brian Gaff.
The email is valid as
Blind user.
"Norman Wells" wrote in message
...
Brian Gaff wrote:
I loved meccano. I used some the other month to make a door closer
for my porch.
Incidentally, Meccano made me a phonograph together with some bits of
tin and a cardboard horn. The cylinder was made from baco foil and of
course had a clunk every rotation, but did actually work surprisingly
well to demonstrate the principals, though speed variability was a
bit of an issue, as was recording time.. grin.
Brian

Wow! It's amazing that it could record time at all. Once you sort the
issues out, you couldn't record a bit for me, could you? I'm sure it will
come in useful in a few years time when I wish I had a bit more.

Yes, they forgot about how hard it is to keep lubricants stable in very
variable conditions on spacecraft. Interestingly, The very old Philips that
Neil Armstrong took with him to the moon had no issues.
Brian

--
From the Bed of Brian Gaff.
The email is valid as
Blind user.
"Martin" wrote in message
...
Did you know that ESRO, the precursor to ESA, used onboard tape recorders
that
were unreliable and a PITA? The failure of one ended up with Esro having
to set
up tracking stations all round the world to get the data in real time that
should have been recorded and downloaded from the tape recorder.

On Mon, 28 Apr 2014 09:18:29 +0100, "Brian Gaff"
wrote:

Well, terms for storage have changed over the years I suppose. I once
worked
out that on a ZX Spectrum, about 5 minutes of cassette tape equalled
32Kbits at 1200 baud, but of course the special loaders games used pushed
the baude rate up so the loading was much faster, and of course less
reliable.

Then of course reel to reel could have several speeds, and the difference
was in frequency responce and noise performance as it was analogue.
If you can explain the difference between analogue storage and digital
storage it might make the penny drop.

Did you know that the Gallileo probe to Jupiter had a tape storage system
on board for use to send the stored data to earth. It started to stick
with
age so they had to spool it back and forwards a bit each time theywanted
to
use it.
More modern space vehicles use Flash ram of course, but these have issues
that tweak their bits when they get hit by a cosmic ray.

More useless information from the web.
Brian
--

Martin in Zuid Holland

www.youtube.com/watch?v=eE_IUPInEuc

In article ,
Bill Wright wrote:
Stephen wrote:

My estimate would be 30 minutes at 3 3/4 inches per second, mono, 10
kHz frequency response, signal to noise ratio 40dB.

My little tape recorder had a non-standard speed of 4ips and also had
the tape wound in a funny way so it played backwards on a normal
machine. For tapes I used to strip down 1/2" computer tape. My uncle
worked at IBM and he used to get it for me.

Bill

There was one from Shoppertunities? which had no capstan so ran at a
different speed depending on where the tape was on the reel...

Happy days.

--
*I'm really easy to get along with once people learn to worship me

Dave Plowman London SW
To e-mail, change noise into sound.

On Mon, 28 Apr 2014 09:59:42 +0100 (BST), "Dave Liquorice"
wrote:

On Mon, 28 Apr 2014 01:40:04 +0100, Johny B Good wrote:

I regard not only CD as pre-historic but DVD and Blu-Ray[1] too. It's
not that that makes me feel old, just the effects of old age creeping
up on me.

Presumably old age is having its normal affect on hearing and sight
so you don't notice how crap downloads and/or streaming are compared
to CD or Blu-Ray (or even DVD come to that). B-)

Well, there's some small element of truth in what you say[1] but the
point I was making was that it seems so futile to 'archive' gigabyte's
worth of audio and terabyte's worth of TV recordings and mpeg movies
onto optical disk media of questionable durability and limited
capacity.

As a backup medium (other than for bootable storage for OS installs
and stand alone software diagnostic tools for use on older PCs that
don't properly support booting from USB flash memory devices), the
limited storage capacity and writing speeds detract immensely over
that of the utility of hard disk storage whether it's in the form of a
simple external USB drive or a NAS box full of HDDs.

A modern 4TB WD RED drive represents about a thousand DVD-R disks
(and around about 200 Blu-Ray disks), so the costs per GB of optical
storage is somewhat similar but without the convenience of HDD and
with a huge performance penalty (less than 25% the speed at best if
you forgo the verification pass required to assure that the data was
successfully written to the media - in practice, with verified writes,
the time penaly is more like getting a mere 10% of the backup speed of
HDD based storage.

Life's just too short to waste on such 'pre-historic' archival
methods (and space so limited too - I gave up using DVD-R archival
storage after writing some 400 DVD's worth when the cupboard started
getting full).

I decided that I would do just as well using the homebrewed FreeNAS
box (now running NAS4Free) to archive my growing collection of media
files, upgrading the jbod array of disks piecemeal to to keep pace
with my ever increasing storage capacity demands.

I've now got a total storage capacity of 13TB's worth of HDDs in the
NAS box and looking to upgrade the smallest (2TB) drive to another 4TB
WD RED by the end of the year.

I'm looking forward to the larger 6TB units becoming available at a
less than eye watering price before the end of 2015. I've been running
a file server of one sort or another for almost the past 3 decades now
and it's rather sobering to think that it all started with a 300MB
full height ESDI HDD in an NEC Powermate II (8MHz clocked 80286 CPU)
running NW 3.11) connected to a 'CheaperNet' lan.

I've now got some 40,000 times that storage capacity today and I dare
say I'll almost certainly have 100,000 times the original storage
capacity before the end of this decade.

[1] As a matter of interest, I was listening to an MP3'd episode of
the Goon Show whilst I was reading your post which I'd extracted from
a 7GB stereo wav file captured from a 24 hour internet radio broadcast
just over nine years ago.

I'm pretty certain I deleted the original 7GB wav file once I'd
processed it into a 54 episode MP3 collection because I couldn't
afford to tie up so much disk space. It'd be a different story today
now that 7GB is such 'a mere trifle' on a 4TB disk but back then, it
wasn't so trifling. Oh, how things have changed in less than a decade!

The station, afaicr, was called "GoonShow Radio" and had a repetoire
of 54 episodes contained in its daily endlessly looped output. I used
Winamp to capture the stream and send its output to a wav file,
letting it run for just over 24 hours. This proved sufficient to
captue all 54 episodes with an episode or three spare.

I'd previously been listening directly to the audio stream for a few
days before, noticing that they were simply repeating a limited number
of episodes every 24 hours, and realised that I could archive the lot
by leaving WinAmp to run for just over 24 hours. I'm glad I did
because the station dropped out of existence a week or two later.

The point is that the original stream was just 64Kbps mono (a
reasonable match to the AM radio broadcast quality most listeners of
the day would have experienced) which, being MP3 rather than the
crappy MP2 standard of DAB was quite sufficient quality (no bubbling
mud effects so typical of a 64Kbps mono DAB broadcast).

Mind you, a higher bit rate would have been appreciated but this was
just over 9 years ago when bandwidth was at more of a premium. The
source material was almost certainly taken from the original studio
recording tapes which could have justified higher bit rates to emulate
FM radio quality rather than the AM radio quality it was re-broadcast
in.

Be that as it may, I still enjoy listening to these shows despite the
limitations of the low bit rate mono MP3 storage method (24 hours
worth packed into the space of a single data CD!).

I've digitised a portion of my reel to reel tapes and vynil to wav
files which I _have_ retained. The 192Kbps stereo MP3s which I
carefully crafted for 'easy listening' purposes are almost
indistinguishable in quality from the original wavs.

The deficiencies only become obvious when I use the "3D Surround"
options on the PC speakers which uses anti-phase cross mixing to
simulate a wider stereo image otherwise the straight playback of this
material seems to be just fine to my aged ears whenever I bother to
compare the MP3 against the original wave file playback.

If I wanted to create a compressed archive of all this audio
material, I'd choose a lossless format to preserve the original detail
in the wav files regardless of my own hearing abilities. The storage
costs for digital audio, even with flash media, is cheap enough these
days to call into question the value of lossless compression.

Lossless compression eliminates unnecessary redundency making the
task of reconstructing the original from a moderately corrupted
compressed file all the more problematic.

I f you want to add an extra level of robustness against 'bit rot' in
the storage media, an effective way is simply to duplicate or even
triplicate the archive files since the ddrescue application can
recreate a bit perfect copy from such corrupted duplicated backups.
IOW, use two or three times the storage media for each backup and keep
ddrescue on hand to refresh your archives as soon as your annual 'spot
checks' reveal the first signs of 'bit rot'.

All archival methods need some level of maintenance to retain their
integrity over protracted periods of time. Even well proven ink on
paper materials need to be checked from time to time even if it's a
matter of maintenence intervals measured in half centuries.

With modern digital storage, we'd be pushing our luck with 5 year
maintence intervals. The only saving grace being the ease with which
exact duplicates can be created on replacement and novel media.
Optical disk storage lost its 'Novelty Factor' decades ago hence my
regard of CDs and the like as being positively 'pre-historic'.
--
Regards, J B Good

In article 6,
says...

Adrian wrote in news:ljjtbl$6au$2
@speranza.aioe.org:

On Sun, 27 Apr 2014 20:31:27 +0100, Bill Wright wrote:

Katie, who is 11, was helping me in the workshop today. She told me how
some of her class been in trouble for filming the teachers covertly. Of
course I told her how, in 1965, I'd made a sound recording of our maths
teacher, with the class deliberately winding him up just to make it more
fun. I then found myself trying to explain about reel-to-reel tape
recorders. I could see that Katie just couldn't grasp the concept.
Finally she asked, "But how much memory did it have?"

I don't know whether to laugh or cry...

It's slightly scary that there's people wandering around who regard the
CD as pre-historic. I feel old.

With the old devices we all had some inkling of how they worked and if we
were to survive some sort of massive global disaster we would have known
enough about the principles to get these devices back in use. Nowadays the
ability to make or even understand common devices is in the hands of very
few people. Who remembers using a pin and some rolled up card to listen to
a 78rpm record?

Much too high tech.

Hold the pin between your teeth & rely on bone conduction.

--
Sam

On Sun, 27 Apr 2014 20:31:27 +0100, Bill Wright
wrote:

Katie, who is 11, was helping me in the workshop today. She told me how
some of her class been in trouble for filming the teachers covertly. Of
course I told her how, in 1965, I'd made a sound recording of our maths
teacher, with the class deliberately winding him up just to make it more
fun. I then found myself trying to explain about reel-to-reel tape
recorders. I could see that Katie just couldn't grasp the concept.
Finally she asked, "But how much memory did it have?"

Bill

Yup, but I bet that in 10 minutes you could have taught her how a
reel-to-reel worked and she would have pretty much understood. No
chance of that with modern mp3 digital equipment.

Thats the biggest difference between the tech of my youth and now -
old stuff was understabndable to the average person.

On a related note, I looked inside a TV that we were binning last
week. Just 2 small circuit boards with precious few components. A
triumph[?] of modern design. The TVs of my youth were full of glowing
valves and thick cables. A thing of wonder, but now look like
something from a Jules Verne film.

How many components in a valve TV?

Incidentally, check out 'photonics' for some amazing old
electronics... eg:

Mercury Arc Rectifier [100 yrs old]
http://www.youtube.com/watch?v=QY6V2syGnZA

Dave Plowman (News) wrote:

In article ,
Bill Wright wrote:

My little tape recorder had a non-standard speed of 4ips and also had
the tape wound in a funny way so it played backwards on a normal
machine. For tapes I used to strip down 1/2" computer tape. My uncle
worked at IBM and he used to get it for me.

There was one from Shoppertunities? which had no capstan so ran at a
different speed depending on where the tape was on the reel...

What about the one which somehow took its drive from a record
player? I'm sure I didn't imagine it, but can't find any details
right now.

Chris
--
Chris J Dixon Nottingham UK


Plant amazing Acers.

"Dave Plowman (News)" wrote in message
...
In article ,
Bill Wright wrote:
Stephen wrote:

My estimate would be 30 minutes at 3 3/4 inches per second, mono, 10
kHz frequency response, signal to noise ratio 40dB.

My little tape recorder had a non-standard speed of 4ips and also had
the tape wound in a funny way so it played backwards on a normal
machine. For tapes I used to strip down 1/2" computer tape. My uncle
worked at IBM and he used to get it for me.

There was one from Shoppertunities? which had no capstan so ran at a
different speed depending on where the tape was on the reel...

Like the Grundig Cub.

--
Max Demian