The Analysis Settings Window

This window allows you to customize the settings that are used to process a specific sample file. These settings can be saved for later use if required in a configuration file. Note that the settings are not automatically saved each time you make a change; you need to click on the Save button

Each setting has a default value, which may be modified as necessary to successfully analyze a sample. You can reset a value to the default by making the entry blank. The tables below explain the meaning and effect of each setting.

Configuration File

For one-off conversions of samples to .P files, you do not need to use a configuration file. The file is useful if you need to re-convert samples.

The name of the currently loaded configuration file is shown at the top of this window. Next to the configuration file name are some action buttons:
Action Description
Load Loads a new configuration file, and updates the settings for the current sample.
Save Saves the configuration file.
Save As Saves the configuration file under a new name.

Sample Settings

These settings apply to the sample as a whole. Additional program-specific settings are explained below.

Note that when a sample is saved under a new name using the File -> Save As menu option, the sample settings are copied to the new name.
Setting Description
Start offset The offset in the sample file at which to start processing.

This can be used to skip noise or other parts of the signal in the sample before the ZX81 program data.

Number of expected programs The number of programs expected in the sample.

If you know in advance the number of programs (tracks) in the sample, or want to convert less tracks than are in the sample, you can enter the number here. Otherwise the converter will process the entire sample for every track it can find.

Minimum gap between programs The minimum gap that should be left between programs.

When the end of a program is identified, analysis continues after skipping this far through the sample. The value is the number of samples at 22Khz.

Invert sample Indicates whether to invert the polarity of the sample.

Some samples appear to have inverse polarity to the majority of ZX81 programs. Inverting the sample will improve the chances of successfully analyzing such samples.

Channel number The channel number within the sample containing the program data.

Best results are obtained from mono samples, in which case the default value can be used. For stereo samples it may be necessary to choose channel 1 if that's where the data is.

Program Settings

These settings apply to each program within the sample. There is one pane which has the default values to be used for all programs (called "Defaults"), and then one pane for each program that has been identified in the sample, whose values can then be overridden from the defaults. These panes are identified by the number of the program in the sample starting at "1". When there is a single program in the sample, only the "Defaults" pane is shown.
Setting Description
Program name The name of the program.

This value can only be set when there is more than one program in the sample. It cannot be set on the "defaults" pane. It defaults to "program" plus the number of the program in the sample, starting at 1.

The program name is used when saving the programs to .P files, and is also used to identify the settings for this program within the configuration file.

Settings key/.P file name The .P file name with this this program will be saved.

This value is calculated from the program name, the number of the program in the sample, and the name of the sample file.

Noise threshold The noise threshold for this program.

Sample values less that the noise threshold are ignored when analyzing the sample. The noise threshold should be around 1)% of the maximum amplitude of the ZX81 program signal. Increase this value if there is a lot of noise in the signal. Alternatively if possible resample the program at a lower volume.

Minimum bit gap The minimum gap allowed between bits in the signal.

The value is the number of samples at 22Khz.

Maximum bit gap The maximum gap allowed between bits in the signal.

The value is the number of samples at 22Khz.

Maximum wave length The maximum length of a single wave in the signal.

The value is the number of samples at 22Khz.

Number of data bytes The number of data bytes expected in the program.

When processing normal ZX81 programs, the program data itself includes information that defines the number of bytes in the signal. Some ZX81 signals do not represent normal ZX81 programs, and in that case this setting can be used to indicate the number of bytes to be expected in the program.