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Extracts the binary content of TZX data blocks to a file.

This tool is useful to migrate tape computer files to modern computers.

It also brings a set of converters to ZX Spectrum BASIC, assembler, ZX Spectrum screens, plain text and hex dump.

This tool also accepts TAP files. They are converted to TZX format internally.


tzxcat [-h] [-b NR] [-o TARGET] [-s BYTES] [-l BYTES]
       [-t] [-B] [-A] [-S] [-d] [-O BASE] [file]
  • file: TZX file to read from, or stdin if not given.
  • -o, --to: Target file. If omitted, stdout is used.
  • -b, --block: Only extract the TZX block with the given block number. If omitted, all data blocks are concatenated to a single output stream. The selected block must be a data block. If the block has a bad CRC, a warning is printed, but the content is extracted nevertheless. If this is not a ZX Spectrum block, a false CRC error is always reported and can be ignored.
  • -s, --skip: Skip the given number of bytes before output. If omitted, nothing is skipped. If it exceeds the block length, an empty block is written.
  • -l, --length: Limit the output to the given number of bytes. The rest of the block is written if this parameter is omitted or if it exceeds the block length.
  • -h, --help: Show help message and exit.

A converter can be applied to the output. If no converter is chosen, the output is just the binary content of the selected block. Available converters are:

  • -t, --text: Convert ZX Spectrum text to plain text.
  • -B, --basic: Convert ZX Spectrum BASIC to plain text. The result is what you would see on the screen after a LIST command. Inline attribute changes are ignored though.
  • -A, --assembler: Disassemble the block, using a simple Z80 disassembler. Undocumented Z80 op codes and Z80N (ZX Spectrum Next) op codes are supported. The disassembler also supports the exit and break pseudo op codes of the #CSpect emulator.
  • -S, --screen: Convert a ZX Spectrum SCREEN$ to PNG. It is recommended to select the SCREEN block using the --block option.
  • -d, --dump: Generate a hex dump of the block contents.

Additional converter options:

  • -O, --org: Define the base address for hex dumps and disassembled code. If not given, the starting address given in the previous Bytes header is used automatically. If there is no such header, 0 is assumed as base address.

Converters use your system's encoding as target encoding. If your system does not use Unicode, the presence of some special characters may lead to an error.


tzxcat --block 4 --to screen.scr game.tzx

Reads the game.tzx file and copies the binary contents of the 4th block to screen.scr.

tzxcat --block 4 --screen --to screen.png game.tzx

The same as above, but now the screen is converted to PNG.

tzxcat --block 4 --text sources.tzx

Dumps block 4 in a (more or less) readable plain text format to stdout.

tzxcat --block 4 --dump sources.tzx

The same as above, but dumps block 4 as hex dump to stdout.

tzxcat --block 2 --basic sources.tzx

Shows block 2 as BASIC listing.

tzxcat --block 6 --assembler sources.tzx

Shows block 6 as disassembled machine code. The starting address of the Bytes header in block 5 is used automatically as the base address.

tzxcat --block 6 --assembler --org 32768 sources.tzx

The same as above, but 32768 is used as fixed base address.

Supported Block Types

tzxcat can extract binary data from all block types containing actual data:

  • 10 - Standard Speed Data Block
  • 11 - Turbo Speed Data Block
  • 14 - Pure Data Block
  • 30 - Text description
  • 31 - Message
  • 35 - Custom info
  • 4B - Kansas City Standard