Close, but no cigar. My 8" drives were 1.2mb and were faster than the
5.25" because they stored more data on a "cylinder" so the head didn't
have to be stepped as often. Also, they had a higher transfer rate.
That's not to say that a good software type couldn't fudge a little on
all 3 types :-).
The 1541 was too rich for my blood back then, I was stuck with the slower,
less expensive, but very reliable 1530 Datasette!
I still remember spending many hours typing in page upon page of raw
machine language from 'Compute!'s Gazette' magazine and saving it to
There were lots of tape backup units in the early hard drive years
that used (basically) an audio cassette type tape for digital data
backup. Everything up untill the advent of DAT was basically an analog
(audio) tape system using modem technology to put the digital data on
the tape using analog technology.
When the moved to helical scan technology the lines started to blurr a
bit more and the data became more digital in it's actual storage -
similar to magneto-resistive recording on "magneto optical drives" and
die sublimation on optical drives. - which were getting awfully close
to the digital technology used for CD ROM and DVD in that there was no
"modulation" used any more.
So if I speak into a microphone "one, zero, one, one, zero ..." then
And yet a cassette recorder has no trouble storing computer files.
Some signalling systems, the various Ethernets for example, are designed
from the ground up to carry digital information. Others, POTS modems
for example, carry digital information over channels that were
originally intended to carry analog data and do so by modulating a
carrier signal that is compatible with that channel.
That's where the distinction lies.
Some casette data can be digital. The cassette tapes used on early
computer systems like the RadioShack COCO (Color Computer) were
digital data stored on an analog medium. There were only 2 tones
recorded on the tape. If the frequency was between 2 levels it was a
1, and between two other totally different frequencies, it was a 0.
Just like RS232, 2 voltage ranges -3 to -25 and +3 to +25 - anything
between -3 and +3 was "noise"
A high quality tape duplicator could duplicate the digital tapes
reliably, but trying to do it with a "dubbing" deck was pretty much
destined to fail. When we had the "coco club" we would get programs
published in "hot coco" magazine, and one member would key the program
into his computer and save it to a cassette tape, then I would run off
the tape on the duplicator so each member got a copy. I used a TELEX
Copyette 4 head duplicator that we also used to make copies of sermon
tapes at church for shut-ins who could not get to church.
(now it's all recorded digitally and put on the church website)
There was no ambiguity. So it was (binary) digital data.
Any music or voice or other non-binary data on a cassette tape is
Then of course, there is DAT (Digital Audio Tape) but that's a
But you're abstracting that cassette recording into '1's and '0's for
the computer (unless you changed subject in the middle of the
paragraph and are talking about audio cassettes).
Yes, there are end-cases that are clearly one or the other. Most of
what we deal with, these days, is not so clear. The distinctions are
mostly just jargon or marketeering, with no real meaning.
The only point I wanted to make was that whether something is digital or
not does not depend on the "carrier". For instance, a drawing is not
digital. It could be digitized, in many different ways...
V 90 was strictly analog. Any "modem" is analog because it modulates
and demodulates (MODulatorDEModulator) the signal at each end.
Modulation is the hallmark of an alalog signal.(modulation also
described, as I did in my "simplified" reply as varying frequency and
A digital signal does not use a "modem" It uses a "codec" (coder
decoder) which converts a binary chain of data to "tokens" and
transmits those "tokens" digitally across the network, and then at the
other end "decodes" the "tokens" to a digital binary data stream
again. All computers today are "digital devices", working with and
understanding ONLY binary digital data.
JPEG, MP3, MP4, GIF, TIFF etc are all compression algorithms that
define what tokens are used and how to code and decode the binary data
The errors and retries in digital communications are the result of the
"error correcting" or "error checking" built into the communication
protocol - if a token arrives damaged, it is rejected and a resend is
In analog communication there is no way to error check and error
correct, so instead of getting data interruption you get data
corruption - instead of getting pixellation and "digital dropout" you
get "snow" "hiss" and other forms of "corruption" in the signal.
In Digital communications you get latency and dropouts.
On Sun, 27 Dec 2015 16:20:27 -0500, firstname.lastname@example.org wrote:
The "modulator" was a D/A converter and the demodulator was an A/D
converter and it was analog in the middle, so the phone line is
analog. How is the communications link digital?
A distinction without a difference. So you're saying that a v.90
modem is analog? DSL is analog? Cable Internet is analog?
There is no practical difference between a "token" and a "symbol".
("Baud" is defined as a symbol per second).
No, they are not for transmission, rather they are standardized
encodings of objects (video, pictures, etc.). Transmission is only
one use for such things (I bet you save some on your computer, even).
So? Internet over a 300bps modem can't have error checking,
correction, or retries?
Really? I guess analog communications never existed (see above).
No, a "modulator" is not a DA converter, and nobody ever said "modem"
communication was digital.
Nope. V90 is straight analog. DSL? I'm not sure. By my definition,
since it uses a Modem, the transmission is a modulated signal - which
means it is an analog signal.
The cable internet uses DOCSIS and QAM, which is technically a CODEC,
not a simple MODEM. QAM is quadrature amplitude modulation - which is
a 4 state "digital" implementation instead of a binary digital - and
ises "tokens" or "symbols" for upstream QAM, but uses MPEG for
Thats as much as I know about HOW it works - and it's different in
north america (6mhz) DOCSIS and 8mhz EuroDOCSIS. - and the fiber optic
backhaul works differently than the coax "last mile" section.
Cable internet is digital - at least mine is. There is no modem. It
runs with a digital router.
On Sun, 27 Dec 2015 19:08:28 -0500, email@example.com wrote:
OK, there is a DSP running the ADC. The second phrase is exactly the
Agreed WRT v.90. Since DSL is *very* similar, I'd say so too but
we're definitely in the minority.
Well, QAM can be more than four state. Forty years ago, we used
9600bps, 1200baud QAM modems (and Motorola called them "modems"), over
dedicated copper phone lines. That's a three-bit (eight state)
MPEG isn't a transmission protocol, rather a compression algorithm.
It may be inside your house but it's using "TV channels" on the pole.
It is a DIGITAL compression algorithm. Impossible to implement in a
strictly analog world.
Docsis is also digital by definition.
ALL TV in Canada is now also digital - whether OTA or cable. Hook up
an analog TV set to any Canadian cable system and just TRY to find a
station you can view. They don't exist - You neet an ATSC tuner or a
digital conversion box.
Try to get a station on an antenna with an NTSC tuner - you won't get
any - they don't exist anymore. ALL digital (atsc) - so just because
it uses a "tv channel" definitely does not preclude it being digital.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.