Introduction: Storing Files on an Audio Cassette

Picture of Storing Files on an Audio Cassette


This will show you how to store any type of file on an audio cassette. Depending on whether you modify the cassette recorder or not, you can get around 1.5 megabytes on a tape. I can get this much space because I increased the speed of the motor inside the recorder to its maximum by jamming a piece of tin foil in the hole at the back of the motor. I also change the sample rates in Audacity to 132300Hz which lets me write the files to the tape much faster. When I record the files, they are recorded at 132300Hz and then the rate is set to 22050 to slow it back down to the rate at which the program can decode it. These modifications are not needed though if you are just experimenting with small files.

You will need:

A cassette recorder with a line in or microphone socket

KCS08 an old program which converts the file into sound for storing. I can not find this program on line anywhere now so I have uploaded it here.
Here is a website with a detailed description of the software:
ftp://ftp.taygeta.com/pub/forth/compilers/native/dos/DXForth/kcs08.txt

The picture of the program will show you what parameters are available.

Audacity
http://audacity.sourceforge.net/

An audio cable to connect the cassette recorder to the line in socket on the computer

Step 1: Encoding Files to Wav

In the attached zip file on the intro, you will find the program. To encode the included bitmap image, simply double click on encode.bat. The program will then create a wav file.

To edit the batch file, right click it and select edit.
Here is what is currently in the file:
KCS -M -Y -U -L5 1.bmp 1.wav

To encode something with a different name or extension, change the 1.bmp which is the input file, and 1.wav which is the output file to a file name of your choice.

Step 2: Recording the Wav Files to Tape.

Open the wav file with Audacity and set the system volume to full. Connect the earphone socket from the computer to the line in on the cassette recorder. Press record and wait a few seconds. Press play in Audacity and wait until the file ends. Stop the recorder a second after the file ends.

Step 3: Reading and Decoding the Files

Picture of Reading and Decoding the Files

To get the files off the tape, you need to connect the earphone socket on the cassette recorder to the line in or microphone socket on the computer. Once you have done this, go into the sound properties in the volume control in Windows and select your recording device. Once you have the settings open, select listen to this device in the listen tab. Set the project rate in Audacity to 22050, Rewind the tape, press record in Audacity and press play on the cassette recorder. Adjust the cassette recorder volume until it is near the top of the sound trace in Audacity. Do not make it too high. After adjusting the volume, rewind the tape, discard the current recording and record the whole thing into Audacity at the same level. Once done, save it as a wav file under the same name as is in the batch file. In this case it is 1.wav. Run decode ignore errors.bat and wait while it decodes. Once it is done, you should see your output file in the same folder as KCS08.

Here is what is inside decode ignore errors.bat
Just change 1.wav and 1.bmp to names of your choice.
KCS -Y -U  1.wav 1.bmp

Comments

Răducu'sC (author)2017-07-10

I have the same problem. Tried multiple cables, multiple casettes, the same result. I encoded a small file. I converted the generated wav file, and it was perfect.

ReddingH (author)2017-05-15

I seem to have run into a problem. I've done everything explained and the audio from the cassette can't be decoded properly. looking at the waveforms in audacity, as you can imagine, the audio produced by the cassette is different from the audio produced by KCS08, as cassettes tend to lack the same precision that a computer does. Because of this, after I read and decode the data from the cassette (A 4KB text file), it decodes as "ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ..."

ReddingH made it! (author)ReddingH2017-05-15

This is what the cassette audio looks like vs. the wav audio I recorded to the cassette, and the result of the decoding. I've tried multiple times with multiple files.

PKM (author)ReddingH2017-05-31

If the second trace is what you got back from the tape recording, your output level when recording is too loud. The signal is clipped (https://en.wikipedia.org/wiki/Clipping_(audio)) which means it's distorting and losing information. Great for electric guitar music, not so great for data storage.

If you try it again, turn down the sound volume on your computer when you record the data to the tape. I'd do this with the output slider in Audacity- put the volume to 50%, let it play for a minute, turn down the volume to 40%, another minute, then 30% etc. You'll then be able to look at what recorded on the tape when you play it back and find the right volume where the audio waveform isn't distorted but is still loud enough.

eppfart (author)2017-05-30

If any of you self proclaimed "old timers" really know about old computers, you would know that the old IBM computers used punch cards and punch tape. Cards can hold about 1 kb per 300 or so cards and read/write speeds are about 10 bytes per second. Tape could read/write at roughly 2 bytes per second and since most tape was reeled up in spools of about a 1000 yards so maybe you can fit a kilobyte on a reel of tape.(which by the way, was 100 pounds.)

PKM (author)2012-08-24

For the kids reading, "audio cassettes" were rewritable audio storage media that existed before iPods ;)

Thanks for the flashback to the days of waiting ten minutes to load a game on my BBC micro... (shudder)

eppfart (author)PKM2017-05-30

A commodore 64 takes a half hour to load a 60 kb game. (also shutter:)

IlgazÖ (author)PKM2016-08-27

I have read that British, BBC or another organisation did a cool thing like "airing" an application from FM radio at late night, you plugged your computer to radio instead of tape and there you had your application.

They also distributed shareware with mags using paper like thin vinyls, carrying data in audio.

People used cassette tape because it was cheap, a diskette drive for a 8 bit Atari or Commodore was more expensive than the freaking computer itself.

3of5 (author)PKM2013-09-23

I was born in 1999 and I started out with floppy disks and CD-RW. IBM and some other company are developing a tape drive that will allow 32 TB of storage. When I heard that Music on tapes were becoming no longer available, I wanted to grab every audio tape I could see when I went garage saleing with my grandfather.

Raúl AlejandroM (author)2014-08-20

Amazing indee, tell me please, if i Do want toget 1.5Mb from a tape, what should i do to my cassette drive?, also, what is the data capacity for the different sizes? (60/90/120).

Thanks a lot! :D

Apparently nobody likes you since there are no replies. And to fit more stuff on your cassette, slow the motor down somehow.

sgt_rock (author)2012-08-23

Shades of my first home computer: TRS80 COCO. If the computer missed the EOF flag, all your work was toast! Ah the good old days. It had 4K of RAM and upgrading to 16K of RAM cost almost as much as the computer itself!

Thanks for your post!

temper (author)sgt_rock2012-08-24

Ditto, I had a TRS-80 clone - cassette based storage - aaah what fun! NOT!
(my code was it really 32 years ago???) Do you remember Micro 80 magazine? best value for money computer magazine ever!

IlgazÖ (author)temper2016-08-27

Everyone purchased the best cassette brand once they typed in an app from magazine for hours, line by line. Funnily enough, if you didn't have a high end cassette deck, that chrome or metal tape created issues with the cheap mechanism :-)

sdobbie (author)sgt_rock2012-08-24

Glad you like it. I did not create the program, I just created the batch files to make it easier to use.

AtariM (author)2016-06-17

wouldnt speeding up the cassette make less storage

AtariM (author)AtariM2016-06-17

because the faster the tape is the farther apart the bits are

SugarCluster (author)2016-03-06

It seems like I am totally out of luck on running this software as it just plain refuses to run under Windows 7 64bit.

cld0000 (author)SugarCluster2016-03-08

Did you try running it under a virtual machine with a DOS guest or DOS emulator?

nihalofficial (author)2015-02-13

It would actually be nice if you can store 1 GB per minute. A 60 Minute cassette tape should equal 60 GB. Storing 1.5 MB on a 60 GB medium seems like a waste to me.

IvanH5 (author)nihalofficial2015-03-03

The bandwidth of the audio tape is not high enough to allow this. Also, where did the author of the instructable state that this was a 60 GB medium? It seems to me like you pulled this 'fact' out of thin air.

blkhawk (author)2012-08-24

Back when personal computers were something out of science fiction, and only a few people could afford them, this was known as sequential access.

Lectric Wizard (author)2012-08-24

Didn't work in the 70s/80s because the tapes stretches...

rimar2000 (author)2012-08-24

Very interesting!

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