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TapeBrowse Utility

For SIMH, Hercules and Desktop CYBER

The TapeBrowse Virtual Tape Browser tool is a Graphical Utility which enables viewing contents of emulated mainframe tape files (Formats: AWS and HET) as well as the SIMH and Desktop CYBER (dtCyber) formatted (TAP) files without having to start a mainframe operating system.

TapeBrowse is written in FreePascal using the Lazarus IDE and is a 64-bit application. Sources are not yet available as it is a work in progress and is evolving. This release is ported to RaspberryPI (ARM), MacOS, Some Linux Architectures.

This Version (2.1) supports:

  • CDC “tap” files (including so-called “padded” tape files)
  • Ordinary (legacy) .AWS files (used by the Hercules emulator and others)
  • Hercules Emulated Tape (.HET) files (which are simply ZLIB/BZIP2 compressed .AWS files)
  • Bus-Tech ZLIB compressed and Flex “FakeTape” (.FKT) files

Viewing Options:

  • Octal / Hexadecimal formats
  • CDC Display Code / ASCII / EBCDIC


Non-MacOS Font Installation

  • This application relies upon the Source Code Pro Google Font. You may also use the Adobe SourceCode Pro (GitHub) version if that's easier to install.
  • It is automatically included in the MacOS Application.
  • The specific typeface invoked is SourceCodePro-Medium.ttf.
  • Install the font in accordance with your operating system's requirements.

Download / Install

  • Download the Zip file that corresponds to the environment you are running:

    MacOS Self-Signing

    On MacOS (recent operating systems), the application may need to be signed before it may be run.

    This is done using the codesign utility in the terminal application.

    The easiest way to accomplish this:

    • Unzip the TapeBrowse.app
    • Move it to the Applications folder.
    • Open terminal
    • Issue the following command (Administrative Access Required):
      sudo codesign -v --force --deep --sign - /Applications/TapeBrowse.app

    You may then launch the TapeBrowse app!

  • MacOS (X86_64 Intel) darwin.x86_64 Note: This is not built for Apple Silicon Architecture. It was built on Big Sur (Intel Core I5).
  • MacOS (AARCH64 M1/M2 Silicon) darwin.aarch64
  • Raspberry Pi linux.aarch64
  • RHEL/Rocky Linux 9 linux.gnu9.x86-64
  • Linux/Ubuntu (LinuxMint) linux.ubuntu.x86-64
  • Windows 10 and Above win64


Linux Variants

Once the application has been unzipped and placed it into the desired location, the application will not launch without setting the “execution” bit. On Rocky Linux 9, the property window appears as it does on the left.

  • use the File Open… menu
  • double-click the tape file to launch the browser
  • The tape format SHOULD be auto-detected regardless of the filetype extension.


When you first load the tape, it is scanned to verify the integrity of the volume.


Tape files are FULLY scanned prior to the primary UI's appearance. Therefore, very LARGE tape files will have a significant lag prior to display of the UI. I'll probably address this in a future version, but that's what a “beta” is about.

About "Padded" .tap Files

This utility automatically accommodates a so-called “padded” TAP format in which there is an off-by-one-byte error between the end of a block and the trailing length word. This is also accommodated in dtCyber.

Until an error is encountered, or end of file is reached, the entire contents will appear in the left-hand window indicating the Block, File, Record, and Length heuristics.

Click on the desired block to display its contents.

Depending on the type of tape detected, the display will automatically adjust accordingly:

  • for 80 byte records, ASCII, EBCDIC and HEXADECIMAL displays are auto-selected.
  • for SIMH tapes, CDC 60-bit Central Memory Word Dump Display (OCTAL with CDC Display Code) is auto-selected.
  • for AWS/HET tapes, HEXADECIMAL with ASCII and EBCDIC displays are auto-selected.

Full copy support is provided (Multi-line select / Copy [Ctrl-C])

TapeBrowse supports all block sizes including “large blocks” up to 2MB or more in size.

Individual Tape files may be any size (over 4GB) up to your operating system and/or filesystem limits.

Next Steps (Known issues)

  • When loading large tapes, the progress bar may not display on non-windows platforms. Workaround: Be patient.
  • Search / Find Function not implemented (anyone need it?)
utilities/tapebrowse.txt · Last modified: 2023/12/31 18:14 by site_admin