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PICList
Thread
'[PIC]: Data Recording to Cassette Tape using QPSK.'
2001\02\22@191853
by
Antonio L Benci
|
part 1 1272 bytes content-type:text/plain; charset=us-ascii (decoded 7bit)
Can anyone point me to information on building or probably purchasing a
QPSK Modulator/Demodulator. I'll be using a 16C874 to collect data and
then dump it to a standard tape recorder. I was considering FSK but QPSK
offers better data density.
Yes, I know, it can all be done with solid state memories, but consider
this , the data interface is RS232C, the proposed data format is TAR
(uncompressed) and the quantity of data is small. Tapes are very cheap
and tape recorders can be purchased for < $50.00 (AUS). The QPSK
interface will hopefully be very cheap to put together. This permits
connection to any PC, Laptop, PDA, UNIX, LINUX, Ultrix, SunOS, IRIX, you
name it work station and OS.
I welcome all pro's and cons.
Nino.
--
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| Antonio (Nino) L. Benci |
| Professional Officer, Electronic Services |
| School of Physics & Materials Engineering |
| Monash University |
| email: spam_OUTnino.benciTakeThisOuT
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2001\02\22@194155
by
Bob Ammerman
Yikes,
I haven't seen a cassette tape interface since my Altair S100 bus days!
There were actually standards for this, try "Kansas City Standard".
Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)
{Original Message removed}
2001\02\22@200431
by
Antonio L Benci
|
part 1 1052 bytes content-type:text/plain; charset=us-ascii (decoded 7bit)
Kansas City is FSK. I'm actually after high data density.
QPSK is/was used for modem data transmission over PSTN so the bandwidth
is no problem for a cassette tape.
Bob Ammerman wrote:
{Quote hidden}>
> Yikes,
>
> I haven't seen a cassette tape interface since my Altair S100 bus days!
>
> There were actually standards for this, try "Kansas City Standard".
>
> Bob Ammerman
> RAm Systems
> (contract development of high performance, high function, low-level
> software)
>
Nino.
--
------------------------------------------------------
| Antonio (Nino) L. Benci |
| Professional Officer, Electronic Services |
| School of Physics & Materials Engineering |
| Monash University |
| email: nino.benci
KILLspamspme.monash.edu |
| T: 61 3 9905 3649. F: 61 3 9905 3637 |
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2001\02\22@201303
by
Bob Ammerman
Yeah, I knew Kansas City was FSK. I was just fondly remembering the good old
days.
You should be able to find an old modem chip that will do the job (if you
can actually source the chip).
Alternatively, you might be able to generate the QPSK with a PIC's PWM
output , but reading it back might be rather challenging.
What bit rate do you hope to achieve?
Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)
{Original Message removed}
2001\02\22@201904
by
Antonio L Benci
|
part 1 1324 bytes content-type:text/plain; charset=us-ascii (decoded 7bit)
Seems that this may be a challenging project ;-)
Bob Ammerman wrote:
>
> Yeah, I knew Kansas City was FSK. I was just fondly remembering the good old
> days.
Such simplicity is lacking these days...
>
> You should be able to find an old modem chip that will do the job (if you
> can actually source the chip).
>
> Alternatively, you might be able to generate the QPSK with a PIC's PWM
> output , but reading it back might be rather challenging.
Decoding it may be too much of a challenge. Bit rate is undecided at the
moment but we're looking at 14.4k as a minimum.
>
> What bit rate do you hope to achieve?
>
> Bob Ammerman
> RAm Systems
> (contract development of high performance, high function, low-level
> software)
>
Nino.
--
------------------------------------------------------
| Antonio (Nino) L. Benci |
| Professional Officer, Electronic Services |
| School of Physics & Materials Engineering |
| Monash University |
| email: EraseMEnino.bencispam_OUT
TakeThisOuTspme.monash.edu |
| T: 61 3 9905 3649. F: 61 3 9905 3637 |
| M: 0414 924 833 |
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part 3 144 bytes
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2001\02\23@020615
by
Nigel Goodwin
2001\02\23@030851
by
kohegyi.laszlo
>>moment but we're looking at 14.4k as a minimum.
>
>around 1200 baud - although I think the Sinclair (Timex?) Spectrum was
>1200 baud all the time.
>--
>
>Nigel.
There were several versions of "Turbo Tape". These made it a lot faster!
Les
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2001\02\23@032123
by
Vasile Surducan
On Fri, 23 Feb 2001 spamBeGonekohegyi.laszlospamBeGone
LN.MATAV.HU wrote:
> >>moment but we're looking at 14.4k as a minimum.
> >
> >around 1200 baud - although I think the Sinclair (Timex?) Spectrum was
> >1200 baud all the time.
> >--
> >
> >Nigel.
>
> There were several versions of "Turbo Tape". These made it a lot faster!
>
>
> Les
>
Yes, but makes many headache to Sinclair users. Everything was OK until
2400 bps, after that very good casette can't store safetly information...
The problem was bandwith and reading-writting head alignment...and of
course the header style and position, I remember well this history.
Vasile
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2001\02\23@032334
by
Chris Carr
> >Decoding it may be too much of a challenge. Bit rate is undecided at the
> >moment but we're looking at 14.4k as a minimum.
>
A Cassette Recorder is not a Transmission System, One has massive amounts of
Wow, Flutter, Jitter, Speed Variations, etc plus most of the deficiencies
present in the other. I doubt that you would get anywhere near 14.4k without
a serious amount of signal processing. Why not use VHS?
Chris
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2001\02\23@040640
by
Alan B. Pearce
>Decoding it may be too much of a challenge. Bit rate is undecided at the
>moment but we're looking at 14.4k as a minimum.
I doubt you will achieve this on an audio cassette with acceptable error rates.
My memories of trying to use audio cassettes with KCS interface was that the
error rate was nothing fantastic, and that was at 300 baud. One had to have
really high quality tapes to achieve reliable recording/playback error rates.
You are trying to do what modems do over clean phone lines, and the wow and
flutter of an audio cassette is going to play absolute havoc with the playback.
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2001\02\23@054355
by
Roman Black
|
Antonio L Benci wrote:
>
> Can anyone point me to information on building or probably purchasing a
> QPSK Modulator/Demodulator. I'll be using a 16C874 to collect data and
> then dump it to a standard tape recorder. I was considering FSK but QPSK
> offers better data density.
>
> Yes, I know, it can all be done with solid state memories, but consider
> this , the data interface is RS232C, the proposed data format is TAR
> (uncompressed) and the quantity of data is small. Tapes are very cheap
> and tape recorders can be purchased for < $50.00 (AUS). The QPSK
> interface will hopefully be very cheap to put together. This permits
> connection to any PC, Laptop, PDA, UNIX, LINUX, Ultrix, SunOS, IRIX, you
> name it work station and OS.
>
> I welcome all pro's and cons.
>
> Nino.
The cons from someone who works repairing
tape decks??
* Head wear (<1 year depends on use)
* belt rubber goes gummy (1-2 years depends on time and heat)
* tape deck motors internal speed control circuits
often failwith high use, giving +/- 5% speed error.
* buildup of crud on heads greatly reduces high freq recording
* tapes stick and bind together
* pinch roller wear pulls tape to side and loses signal
Being construcive now, try to avoid high freqs.
(stay under 1kHz if possible.)
Use lots of error checking, checksums,
repeated data, redundancy.
Software tape speed checking.
Use a good tape deck.
Lots of regular cleaning, lubing and tape replacement.
Only use good 60 min tapes. 90 and 120 use thinner
less reliable tape.
Use a good gloss tape for less head wear.
For this much work, why not try hacking a
3.5" floppy drive, it has two stepper motors,
one for spin and one for head translate.
Not too hard!
If you are making the hardware yourself
this gets you past belts and tape speed and
pinch roller problems. You only want low data
rates so you can make it many times more reliable
than a normal floppy, which is already 100x more
reliable than a tape system...
Just a thought?? :o)
-Roman
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2001\02\23@064118
by
Walter Banks
|
Cassette tapes, haven't head that for a while. The
tape format on Coleco ADAM was designed to be reliable
(inexpensive) as possible. We used fixed length data
blocks with each block having sync and header information
with dead space between blocks so that even with bad tapes
most of the data could be read.
Most of the modem technology will not work very well
with cassette tape recorders. The issue is the
amount of jitter induced in the data from the mechanics
of the recorder.
My guess is you can develop a floppy disk interface for
the 16C874 that would also give you portability,
reliability and a cost effective solution.
Walter Banks
Bob Ammerman wrote:
{Quote hidden}> I haven't seen a cassette tape interface since my Altair S100 bus days!
>
> There were actually standards for this, try "Kansas City Standard".
> > Can anyone point me to information on building or probably purchasing a
> > QPSK Modulator/Demodulator. I'll be using a 16C874 to collect data and
> > then dump it to a standard tape recorder. I was considering FSK but QPSK
> > offers better data density.
> >
> > Yes, I know, it can all be done with solid state memories, but consider
> > this , the data interface is RS232C, the proposed data format is TAR
> > (uncompressed) and the quantity of data is small. Tapes are very cheap
> > and tape recorders can be purchased for < $50.00 (AUS). The QPSK
> > interface will hopefully be very cheap to put together. This permits
> > connection to any PC, Laptop, PDA, UNIX, LINUX, Ultrix, SunOS, IRIX, you
> > name it work station and OS.
> > Nino.
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2001\02\23@064948
by
Peter L. Peres
QPSK and most other phase encoded data formats do not pass audio tape, and
just barely pass FM channels, on account of the induced phase noise etc.
F.ex. recording modems on audio tape over 4800 Bauds is very difficult
even on high end audio tape recorders.
Peter
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2001\02\23@081823
by
Drew Vassallo
> > Can anyone point me to information on building or probably purchasing a
> > QPSK Modulator/Demodulator. I'll be using a 16C874 to collect data and
> > then dump it to a standard tape recorder. I was considering FSK but > I
>welcome all pro's and cons.
Pros: original, new interface
Cons: spend the extra $100 and buy a CD-RW burner
--Andrew
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2001\02\23@090513
by
Alan B. Pearce
2001\02\23@122057
by
Harold M Hallikainen
|
I did some "Kansas City" stuff using the XR2206 and XR2211. Even bought
software (an integer basic interpreter for the MC6800) on cassette from
Southwestern Technical Products.
Something that MIGHT work is a technique I used to drive a digital tape
drive (the Exatron (I think that was their name) "Stringy Floppy"). I did
it in 6800 assembly, but it could easily be done in PIC assembly. The
coding is similar to bar coding. You send a pulsetrain to the tape and
time between transitions. A long time is a 1, a short time is a 0. You
get one bit per transition. I also had the threshold adjust under
software control to allow the tape speed to vary (bit times were measured
and the appropriate threshold calculated). There will probably be a DC
component to the signal going to the tape that will be lost, but you can
"restore" it using a clamper.
Harold
On Fri, 23 Feb 2001 12:19:16 +1100 Antonio L Benci
<TakeThisOuTNino.BenciEraseME
spam_OUTSPME.MONASH.EDU.AU> writes:
{Quote hidden}> Seems that this may be a challenging project ;-)
>
> Bob Ammerman wrote:
> >
> > Yeah, I knew Kansas City was FSK. I was just fondly remembering
> the good old
> > days.
>
> Such simplicity is lacking these days...
>
> >
> > You should be able to find an old modem chip that will do the job
> (if you
> > can actually source the chip).
> >
> > Alternatively, you might be able to generate the QPSK with a PIC's
> PWM
> > output , but reading it back might be rather challenging.
>
> Decoding it may be too much of a challenge. Bit rate is undecided at
> the
> moment but we're looking at 14.4k as a minimum.
>
> >
> > What bit rate do you hope to achieve?
> >
> > Bob Ammerman
> > RAm Systems
> > (contract development of high performance, high function,
> low-level
> > software)
> >
>
> Nino.
> --
> ------------------------------------------------------
> | Antonio (Nino) L. Benci |
> | Professional Officer, Electronic Services |
> | School of Physics & Materials Engineering |
> | Monash University |
> | email:
RemoveMEnino.benci
TakeThisOuTspme.monash.edu |
> | T: 61 3 9905 3649. F: 61 3 9905 3637 |
> | M: 0414 924 833 |
> ------------------------------------------------------
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2001\02\23@130213
by
Bob Ammerman
There were several direct digital to tape techniques that used a hacked tape
drive. Manchester encoding tends to work pretty well.
But going through the audio electronics really limits you.
Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)
{Original Message removed}
2001\02\23@163929
by
Bill Westfield
>Cons: spend the extra $100 and buy a CD-RW burner
Or an IDE interface tape drive?
Or hard drives. Tape might have annoying streaming requirements (as do
CD-RW in many formats.) Or flash memory.
Let's see. 45 minutes on one side of a tape is about 19Mbytes if you could
get 56kbps (not likely.) While tape and tape transport is seriously cheap,
compact flash (or similar technology) in approximately that size (16MB)
isn't very expensive, either.
(say - if you really want to store stuff on normal casette tapes, would you
be better off stripping down your recorder/playback unit to NOTHING except
the transport mechanism and putting in your own electronics?)
BillW
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2001\02\24@041324
by
Chris Carr
|
> (say - if you really want to store stuff on normal casette tapes, would
you
> be better off stripping down your recorder/playback unit to NOTHING except
> the transport mechanism and putting in your own electronics?)
>
Hi Bill, that stirred one of my ancient brain cells. If I remember correctly
(and I probably don't) you fed Manchester Code directly into the record
head. On playback each transition produces a positive or negative pulse
which allows the original signal to be reconstituted. I never tried it
myself so why I should remember it puzzles me.
I still doubt that 14.4kb/s is achievable on a cassette recorder,
unless....If you had a recorder with 4 channel heads you could split the
signal into 4 parallel channels which would give a speed of 3.6kb/s per
channel which would be achievable, that only leaves tape skew and sundry
other mechanical effects to deal with.
Regards
Chris
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2001\02\24@135344
by
Thomas McGahee
|
I have a circuit I designed about ten years ago that reliably
records and reads back data to/from standard cassette recorders
at 2400 baud. It uses CMOS logic and is crystal controlled.
The circuit was originally designed to allow me to transfer
DATABASE info between some old CP/M machines and IBM PCs. A small
adapter cable also allowed me to transfer data from some APPLE
computers to IBM PCs that were located in different buildings.
Once the audio levels were properly adjusted for the recorder
being used, this circuit worked beautifully.
I built two of these using wire-wrap. I still have them, though
I haven't used them in years. Once we had transferred the needed
data I just put them in storage. Oh yes, we did take them out of
storage once to use them as a download/upload device for a
datalogger, when we didn't have a portable computer available
at the moment. So the last time one of them was used was
about two years ago.
The design is mostly digital, with analog only being used at
the RS232 ends. You MIGHT be able to push this to 4800 baud
just by changing the crystal to double its present value,
but it is the TAPE itself that sets the limit. Ordinary tape
can have a certain amount of drop-out, though nowadays
you could probably go with a high-end tape with few problems.
{Original Message removed}
2001\02\25@181331
by
Antonio L Benci
|
part 1 1206 bytes content-type:text/plain; charset=us-ascii (decoded 7bit)
Yes, for FSK data. I'm looking at using QPSK, which was/is a form of
phase modulation used in modems. The PSTN bandwidth is ~3.8KHz (please
correct me if i'm wrong) so consider how does a 56K modem work on a
3.8KHz bandwidth analogue line. Lots of magic with those modems hey ;-)
Nigel Goodwin wrote:
>
>
> I don't remember any of the old cassette systems reaching anywhere near
> that (nor the Commodore 1541 floppy disks for that matter). The standard
> cassette systems used 300 baud, and you could often use a faster system
> around 1200 baud - although I think the Sinclair (Timex?) Spectrum was
> 1200 baud all the time.
> --
>
Nino
--
------------------------------------------------------
| Antonio (Nino) L. Benci |
| Professional Officer, Electronic Services |
| School of Physics & Materials Engineering |
| Monash University |
| email: EraseMEnino.benci
spme.monash.edu |
| T: 61 3 9905 3649. F: 61 3 9905 3637 |
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2001\02\25@181539
by
Antonio L Benci
|
part 1 719 bytes content-type:text/plain; charset=us-ascii (decoded 7bit)
Please enlighten me !
RemoveMEkohegyi.laszloTakeThisOuT
spamLN.MATAV.HU wrote:
>
>
> There were several versions of "Turbo Tape". These made it a lot faster!
>
> Les
>
Nino.
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| Antonio (Nino) L. Benci |
| Professional Officer, Electronic Services |
| School of Physics & Materials Engineering |
| Monash University |
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2001\02\25@181953
by
Antonio L Benci
|
part 1 1045 bytes content-type:text/plain; charset=us-ascii (decoded 7bit)
Point taken with the Transmission System.
Design criteria:
Portable, light weight , small...
A VHS recorder does not meet these requirements.
Chris Carr wrote:
>
> A Cassette Recorder is not a Transmission System, One has massive amounts of
> Wow, Flutter, Jitter, Speed Variations, etc plus most of the deficiencies
> present in the other. I doubt that you would get anywhere near 14.4k without
> a serious amount of signal processing. Why not use VHS?
>
> Chris
>
Nino
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| Antonio (Nino) L. Benci |
| Professional Officer, Electronic Services |
| School of Physics & Materials Engineering |
| Monash University |
| email: spamBeGonenino.benciSTOPspam
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2001\02\25@182205
by
Antonio L Benci
2001\02\25@182417
by
Antonio L Benci
|
part 1 1118 bytes content-type:text/plain; charset=us-ascii (decoded 7bit)
Thanks for the pointer...
I'ts now looking like the idea may end up in the too hard basket |-(
"Peter L. Peres" wrote:
{Quote hidden}>
> QPSK and most other phase encoded data formats do not pass audio tape, and
> just barely pass FM channels, on account of the induced phase noise etc.
> F.ex. recording modems on audio tape over 4800 Bauds is very difficult
> even on high end audio tape recorders.
>
> Peter
>
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2001\02\25@182621
by
Antonio L Benci
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part 1 2055 bytes content-type:text/plain; charset=us-ascii (decoded 7bit)
Muchos gracia for the technical notes and cons. The idea has now been
shelved. (-(
Roman Black wrote:
{Quote hidden}>
>
> The cons from someone who works repairing
> tape decks??
>
> * Head wear (<1 year depends on use)
> * belt rubber goes gummy (1-2 years depends on time and heat)
> * tape deck motors internal speed control circuits
> often failwith high use, giving +/- 5% speed error.
> * buildup of crud on heads greatly reduces high freq recording
> * tapes stick and bind together
> * pinch roller wear pulls tape to side and loses signal
>
> Being construcive now, try to avoid high freqs.
> (stay under 1kHz if possible.)
> Use lots of error checking, checksums,
> repeated data, redundancy.
> Software tape speed checking.
> Use a good tape deck.
> Lots of regular cleaning, lubing and tape replacement.
> Only use good 60 min tapes. 90 and 120 use thinner
> less reliable tape.
> Use a good gloss tape for less head wear.
>
> For this much work, why not try hacking a
> 3.5" floppy drive, it has two stepper motors,
> one for spin and one for head translate.
> Not too hard!
>
> If you are making the hardware yourself
> this gets you past belts and tape speed and
> pinch roller problems. You only want low data
> rates so you can make it many times more reliable
> than a normal floppy, which is already 100x more
> reliable than a tape system...
>
> Just a thought?? :o)
> -Roman
>
Nino.
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2001\02\26@005915
by
Bill Westfield
Design criteria:
Portable, light weight , small...
A VHS recorder does not meet these requirements.
Says who? Think VHS-C palmcorder... you can get a lot smaller with
8mm tape, of course...
BillW
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2001\02\26@050616
by
Alan B. Pearce
>You haven'y heard my phone line lately ;-)
so what rate does your modem automatically drop back to??? :)
Or maybe your modem just drops the phone line due to noise? Been there, had the
dropped transmission - almost at the end of a large download.
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2001\02\26@084427
by
Olin Lathrop
> Yes, for FSK data. I'm looking at using QPSK, which was/is a form of
> phase modulation used in modems.
Phase modulation can be bery tricky with tape due to the speed flutter.
*****************************************************************
Olin Lathrop, embedded systems consultant in Devens Massachusetts
(978) 772-3129, olinEraseME
embedinc.com, http://www.embedinc.com
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2001\02\26@171228
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Antonio L Benci
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part 1 1067 bytes content-type:text/plain; charset=us-ascii (decoded 7bit)
About 50% of the time it drops to 14.4k. I've harassed the local telco
regarding the line quality and every time they've come back with "No
Problem Found".
It gets very frustrating....
"Alan B. Pearce" wrote:
>
> >You haven'y heard my phone line lately ;-)
>
> so what rate does your modem automatically drop back to??? :)
>
> Or maybe your modem just drops the phone line due to noise? Been there, had the
> dropped transmission - almost at the end of a large download.
>
Nino.
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2001\02\28@221405
by
Alejandro Lavarello
|
Hi, Nino!
If you dont need high density of information,
perhaps you can use a modem in a chip, like 74HC942
or MC145442/3 and attach it at the serial port of the PIC.
I think that you can record the 1200/2200 Hz in the tape
without problems.
I think that, with a modem like this, your application
not only can record data, but also can send and receive
data in real time using a communication standard (Bell 103
or CCITT). Most of modems today still supporting this
standard in order to mantain compatibility.
Well, these are my ideas...
Regards,
Alejandro.
At 11:18 23/02/01 +1100, you wrote:
{Quote hidden}>Can anyone point me to information on building or probably purchasing a
>QPSK Modulator/Demodulator. I'll be using a 16C874 to collect data and
>then dump it to a standard tape recorder. I was considering FSK but QPSK
>offers better data density.
>
>Yes, I know, it can all be done with solid state memories, but consider
>this , the data interface is RS232C, the proposed data format is TAR
>(uncompressed) and the quantity of data is small. Tapes are very cheap
>and tape recorders can be purchased for < $50.00 (AUS). The QPSK
>interface will hopefully be very cheap to put together. This permits
>connection to any PC, Laptop, PDA, UNIX, LINUX, Ultrix, SunOS, IRIX, you
>name it work station and OS.
>
>I welcome all pro's and cons.
>
>Nino.
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