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Magnetic tape data drive

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Ibizibbik

New Member
Hi all, im new to the whole forum thing but here we go.

I would like a retro reel to reel style or similar data drive for my modern pc mostly as a novelty. I was thinking about using cassette tapes, and storage size and read/write speeds dont matter. How would i go about doing this? Would it be too hard? I would probably need some software to make it work correct?

Any help or insight would be very appreciated.
 

dougy83

Well-Known Member
If you're happy to have to control the play/stop/record buttons manually, then all you need in terms of hardware is a couple of audio cables from the cassette deck to the PC soundcard (you may want to get an additional USB soundcard for this so you can still use the PC speakers as before). You'll then need a program to play or record from the tape via the soundcard, and to (de)modulate the audio signal into digital data. You can use almost any language to write the program; MATLAB or Octave are good to start with as they have inbuilt functions for record/playback and I think even the (de)modulation routines.
 

Ibizibbik

New Member
If you're happy to have to control the play/stop/record buttons manually, then all you need in terms of hardware is a couple of audio cables from the cassette deck to the PC soundcard (you may want to get an additional USB soundcard for this so you can still use the PC speakers as before). You'll then need a program to play or record from the tape via the soundcard, and to (de)modulate the audio signal into digital data. You can use almost any language to write the program; MATLAB or Octave are good to start with as they have inbuilt functions for record/playback and I think even the (de)modulation routines.
What i want is something to act as an external data drive, for all data, not just music. So auto read/write is a must.
 

alec_t

Well-Known Member
Most Helpful Member
The main problem with a tape drive is that it is not random access, so it can take ages to reach a desired part of the tape to read/write data. That makes it unsuitable for storing small blocks of data which might need to be accessed frequently or rapidly; but suitable only for, say, loading application software initially (as was done for the Commodore 64, for example), or for arhiving a large block of data needing only occasional access.
 

tomizett

Active Member
I think the nicest way to do this (especially since you're looking for a retro and novelty item) would be to use a modem.
A simple old-fashioned serial modem could be connected between tape and PC, making the tape drive look just like a serial terminal.
 

Les Jones

Well-Known Member
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In the 1970s DEC (Digital Equipment Corporation) had two tape devices that behaved in a similar way to disk drives. They were the TU56 (Also called DECtape.) and the TU58. The TU56 was open reel tape and the TU58 was a type of cassette. Although they were random access devices they were very slow compared with a disk drive.

A standard that was used with audio cassette tapes to record data was Kanssas city standard.
See this link.

Les.
 

dr pepper

Well-Known Member
Most Helpful Member
If I understand this right you need to interface the tape player controls to the pc so it can auto fastwind and play, and while fastwinding still be able to detect markers on the tape, you need this for random access.
This requires a fairly indepth mod to a tape player recorder, you can get them with a serial interface, however the cost will be high, might be better to find one that has switches instead of mechanical piano keys for the controls, then you can fairly easily hack the switches to pc control.
You might have to create your own program for the pc too, finding one that will control a mechanical deck and look for markers while fastwinding wont be easy.
 

djsfantasi

Member
Yes. Most tape decks have mechanical controls. I used a variation of the modem/cassette deck to save my bacon in college. The mainframe crashed and most students lost my projects. I had mine on tape and submitted it on time. Of course, the other students got an extension but I got extra credit. I would say that the modem and reel to reel would save a lot of development. Random access is still a problem.
 

spec

Well-Known Member
Most Helpful Member
One approach you could use is to have a tape loop. You would then only need to issue a tape start command. Access time to any piece of data would be proportional to the length of the loop.

In terms of transports there are commercially: cheap cassette players, hiFi cassete players, cartridge, and reel to reel. Reel to reel running at 15 inches per second (IPS) or even 30 IPS would give the best performance. For an even better performance you could use a standard video player (VHS) which would probably be your best bet. We had a project at work (I was not involved) where they used a Sony Betamax player as a backing store and it worked quite well.

Having chosen the mechanical transport, you would then need to choose the bit level encoding system- Kansas City as Les says for a cheap cassette player: 1.2KHz and 2.4Khz tones representing 0 and 1.

Having done that you could possibly adapt a protocol for a standard computer tape drive or possibly a floppy drive.

Just a few ideas

spec
 
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JonSea

Well-Known Member
Most Helpful Member
Years ago, I used a 300 baud modem to encode "log book" information on one track of a 7 track 1/2" tape recorder along with 6 vibration data tracks for machinery condition analysis. The encoded track identified what machine the data was from, the measurement locations for each channel, all the gain settings for each channel and the FFT analysis ranges required for each channel.

When the data was played back, a modem read the data track, recovered all the log book information and then cycled the tape back and forth to produce the required FFT spectral plots. It was amazing to watch the first reel of tape being analyzed! Instead of a tedious manual process, the tape cycled back and forth a number of times for each recording and spectral graphs started pouring out of the plotter. A typical vibration survey's data reduction time was reduced from 3 man-weeks to 8 hours! All that was needed was somebody to change tape reels as each one was completed to keep the process moving along.

300 baud isn't a very fast data rate but it was way more than needed to encode the necessary information for each one minute recording. In processing thousands of data recordings, I can only recall a few that couldn't be read back reliably. It was an extremely reliable system.

One additional features was very nice. Each recording required several pieces of information and when writing that information in a log book, crucial information could be missed. With a computer writing the information to tape, it forced filling in all the blanks before the recording would start.

I encoded the data in formatted ASCII text rather than trying to compress it in any way. That way, any modem and terminal could be used to view the data encoded on the tape. Not specific program was required to convert the data into a viewable format if there was any question about it.
 
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