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TapeBrowse Utility (beta)

For SIMH and Desktop CYBER

The TapeBrowse Virtual Tape Browser tool is a Utility which enables you to view the contents of emulated mainframe tape files (Formats: AWS and HET) as well as the SIMH and Desktop CYBER (dtCyber) formatted (TAP) files from the Windows desktop 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. FreePascal was chosen since I intend to port this to RaspberryPI (ARM), Mac, Linux (x86) Architectures in the future.

If you need something more sophisticated / specialized for viewing ZLIP/BZIP2 internally formatted tapes - have a look at AWSBrowse by SoftDevLabs. It supports both ordinary (legacy) .AWS files and Hercules Emulated Tape (.HET) files (which are simply ZLIB/BZIP2 compressed .AWS files), as well as Bus-Tech ZLIB compressed and Flex “FakeTape” (.FKT) files too.


  1. Download the Zip file from the Utilities page.
  2. Place the contents in whatever location you wish
  3. Associate the .tap .het and/or .aws extension with the newly unloaded executable
  4. Launch the application and
    1. use the File Open… menu
    2. double-click the tape file to launch the browser


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.

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.


Automatic update checks for latest version may be done by using the “Help/Update Check” Menu item.

You will be presented with a message indicating whether or not there is an update available to you.

If there is an update available, it will be downloaded automatically but you will need to extract the contents to the appropriate location.

Next Steps (Known issues)

  • Search / Find Function not implemented
  • Improved / corrected function key support
  • Menu cleanup and fixup of Option Overrides
utilities/tapebrowse.txt · Last modified: 2022/05/28 13:05 by site_admin