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Cassette Decoder

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KCS08 & Converting Audio To Tape

What you hear on the B side of your Space EX Cassette is data encoded into audio files, wav files to be specific. One of the most popular early ways to store computer programs on audio cassettes was the Kansas City Standard (also known as the 'BYTE standard'). Developed in 1975, it uses an encoding scheme where a '0' bit is represented as 4 cycles of 1200Hz and a '1' bit as 8 cycles of 2400Hz. The data rate is 300 bits per second.

Once decoded, the files you'll find on this cassette include Bitmap Images (.bmp files) as well as the original .mod files from the Space EX soundtrack. Bitmap images can be opened with most image viewers. Mod files can be opened with any music tracker (MilkyTracker/OpenMPT etc). Please note that when opening .mod files, the session sometimes reverts to its default tempo (125bpm). To hear the songs the way we originally intended, raise the tempo to 150bpm on your tracker software.

We've prepared two zip files for anyone interested in finding out what files are stored on the cassette. The package titled
"KCS08 Master Cadet" includes ready-to-use batch files already programmed to decode the provided audio, while the package titled "KCS08 Master Sergeant" includes only the software, and generic encoding/decoding batch files for a bit of fun programming. Detailed instructions are provided for both instances.

Try encoding some of your own files and experimenting yourself, it's free!

*Tested on Windows XP 32-Bit. Software may not work on modern hardware.

Space EX Cadet Decoder

Step 1
Click the download button above and unzip the file provided.


Step 2

You should see a folder inside titled 1. Sub, we'll get to that later. All you need to interact with are the decode files titled P01, P02, P03, etc. (as indicated in screenshot below). Double click any of those files and a command prompt will appear and disappear after the decoding process is complete.

KCS08 Master Cadet A.png
KCS08 Master Cadet B.png

Step 3
After the audio has finished decoding, a new file will appear in the main folder. The new file name will correspond with the original file name. Eg.
Decode P01.bat = P01.bmp. Note: Larger files will take longer to decode.

KCS08 Master Cadet A.png
KCS08 Master Cadet C.png

Step 4
In the
1. Sub folder you'll find the official Readme along with generic encode/decode files. Feel free to experiment with these to convert your own files into audio. Detailed instructions given during the Sergeant Decoder walkthrough below.

Space EX Sergeant Decoder

What you need
Cassette Player
DAW of choice (Pro Tools/Logic Pro etc.)
Computer (Tested with Windows XP 32 bit)


Step 1 - Downloading
Click the download button above and unzip the file provided.


Step 2 - Bouncing Audio In and Out

Put the unzipped folder aside for now, you'll need it in order to convert your audio back to files. Right now we want to bounce our audio off the tape into our DAW of choice. Make sure it's a clean, hot signal, almost to the point of peaking. Tip: Keeping everything mono is your best bet when recording the signal from tape to digital. When bouncing audio out of our DAW, the specifications are crucial and must be followed correctly, otherwise the decoding process will result in failure. It's important to name your WAV files something simple so there's no confusion wen decoding. We'll use the filename A01 for this example. Here are the audio output specifications:

 

Bit Rate:          176 kbps
Sample Size:   8 bit
Channels:        1 mono
Sample Rate:   22kHz
Audio Format:  PCM
File name:        A01

Step 3 - Preparing Your DOS Batch Files
With your new WAV file bounced out including the correct specifications, it's time to decode the data. Place your WAV file in the main folder KCS08 Master Sergeant. Right click on the file titled decode ignore errors.bat and choose Edit. This file can be edited in a normal text editor. You should see the following script:

KCS -Y -U  FILENAME.wav FILENAME.bmp

We need to replace the words titled FILENAME to what we named our WAV file in Step 2. In this case it's A01. Save the file and exit the Text Editor.

KCS -Y -U  A01.wav A01.bmp

NOTE: The last two tracks are .mod files and must be specified in the decode ignore errors.bat code.

KCS -Y -U  A01.wav A01.mod

Step 4 - Decoding Your Audio
After your newly edited batch file is saved, you can now execute the command by double clicking on the file. You should see a command prompt pop up for a brief second. Don't touch it, just let it finish.

KCS08 Master Cadet B.png

Step 5 - Viewing Your Files
If everything was done correctly, a new file will pop up in the main folders directory. In this case, we decoded the first Bitmap Image hidden on the B side of the Space EX Soundtrack! Remember, the last two track on the cassette are .mod files and should be specified within the Batch files output code.

Step 6 - Encode Your Own Files (Optional)
To encode your own files, simply right click on encode.bat (batch file) and choose edit. The FIRST FILENAME is your input file, while the SECOND FILENAME is your output file. Your input file can be anything from PNG, text documents, applications, videos, passwords, basically anything digital. In this example we'll look at encoding a text document. Note: Yellow is input, Red is output. Just replace FILENAME with your files. To decode, revert to Step 3.

KCS -M -Y -U -L5 FILENAME.bmp FILENAME.wav

KCS -M -Y -U -L5 document.txt document.wav