Java ZX81 Tape Converter Overview

The Java ZX81 Tape Converter allows you to to convert sampled sounds to ZX81 .P and .TZX files, and vice-versa. It requires Java 1.4 to run.

Latest Update 08/05/2020 added command line option to save to a .TZX file.

Here are a couple of screenshots. The first is with the converter running against a single file:

The second illustrates the program running with two samples, where the first difference between them has been located. You can also see where a "0" has been manually added to the second sample where there was a drop-out:

The ZX81 Tape Converter is package as a .JAR file: Click here for the .jar file.

If you have any comments/requests/suggestions, please send a note to Simon Holdsworth

GUI operation

The Converter can be run by executing the .JAR file. This can be done in Windows by double-clicking on the .JAR icon (assuming you have the correct association for .JAR files with javaw.exe).

It can also be run from the command line using:

javaw -jar tapeutils.jar

The help for the program can be found here, as well as within the program itself.

I'd recommend setting the maximum memory usage for the Java program because the default is usually quite low. Also if you hit OutOfMemory errors, then this is something that needs increasing. Assuming you have 1G RAM or more, you can use:

javaw -Xmx750M -jar tapeutils.jar

Command line operation

It is also possible to run the program fully from the command line. Here are the command line arguments:

java -jar tapeutils.jar 
      {-sampleFile |-s} fileName     The name of the sample file (.WAV, .AIFF, etc.)
     [{-sample2File|-2} fileName]    The name of the second sample file (.WAV, .AIFF, etc.)
     [{-pFile      |-p} fileName]    The name of the .P file to save to.
     [{-tzxFile    |-t} fileName]    The name of the .TZX file to save to.
     [{-gui        |-g}]             Display GUI.
     [{-invert     |-i}]             Invert sample.
     [{-noise      |-n} noiseLevel]  Noise threshold.
     [{-minGap     |-m} minGap]      Minimum gap between groups.
     [{-maxGap     |-x} maxGap]      Maximum gap between groups.
     [{-channel    |-h} channel]     Channel number.
     [{-data       |-d} numBytes]    Data only.  Don't interpret as a BASIC program.
     [{-forceWrite |-w}]             Force write of result after errors.        
     [{-begin      |-b} index]       Index within sample to start processing.
     [{-multiFile  |-f} fileNames]   Comma-separated file names for multiple within the sample.
     [{-configFile |-c} configFile]  Name of a properties file with convert parameters.

Examples converting files without showing the GUI.

java -jar tapeutils.jar -s "3D Monster Maze.wav" -p 3dMonsterMaze.p -g
java -jar tapeutils.jar -s "SuperPrograms5.wav" -tzx SuperPrograms5.tzx -g

Some tips on using the program

• All blocks should be 4 waves (cyan = a 0 bit) or 9 waves (blue = a 1 bit). Anything else is likely to be noise on the tape. The converter does try to ignore noise in between the bits but does not always get it right. One thing you can try is modifying the noise threshold - that is indicated by the two black lines above and below the middle line. Any signal between these two lines is ignored.
  Analysis -> Analysis Settings -> Defaults -> Noise Threshold - try setting to 20 for a lot of noise, default is 5.
• There is often a lot of noise on the tape before the actual program, again the program tries to ignore this, but you can either remove it in a wave editor or set the "start offset" to the point in the sample where conversion should start.

Here's a more detailed explanation of the parameters:

Biorhythms.B.noise=19
Biorhythms.B.invert=true
Forth.3.EditorScreen1.numDataBytes=1028
MCoder.minGap=38
Pimania.begin=55700
Games1.A.Multi.fileNames=Orbit,Sniper,Meteors

.P List/Play/Save

This standalone utility allows the contents of a .P file to be listed, played as a sample through the computer speakers, or saved as a sampled sound for later playing.

At the moment this utility can only be run from the command line. It takes the following arguments:

java -classpath tapeutils.jar tapeutils.zx81.PFileUtils
      {-pFile     |-p}  fileName    The name of the .P file.
     [{-sysVars   |-s}]             Output system variables.
     [{-vars      |-v}]             Output program variables.
     [{-display   |-d}]             Output display file.   
     [ -play          ]             Play the file rather than listing it.
     [{-sampleFile|-f}] fileName    The name of the file to write the sample to.
     [{-zx81Name  |-z}] name        The name of the ZX81 file (not needed for list).

If -play is specified, the file is played, rather than being listed; if a sample file name is provided, then the file is saved to the sample file only - the -play option is ignored in that case. Note that you can also play .P and .TZX files from the ZX81 Tape Converter, and save the resulting sample file for later playback too.

An example:

java -classpath tapeutils.jar tapeutils.zx81.PFileUtils -p "3DMonsterMaze.p -play -z "3D MONSTER MAZE"

Note that the ZX81 file name must contain only valid ZX81 characters (so no lower case...).

It's also possible to implement your own classes to analyze sound samples of different types, through the interfaces in the tapeutils package, with ZX81 specific implementations in the tapeutils.impl.zx81 package, although at the moment the conversion utility always uses the ZX81 versions.

Click here for (a .zip of) the javadoc