===================================================================================
  SeaMAC
  Software support package for Sealevel synchronous serial product family.
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  Software Release Note
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  Version 6.0.21
  Copyright (c) 2002-2026 Sealevel Systems, Inc.
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This document describes the Sealevel Systems SeaMAC for Windows software release.

This document is divided into the following sections:
    - Description
    - Requirements
    - Changes
    - Known Issues
    - Technical Support



Description
===========
    SeaMAC provides a powerful WIN32 interface (CreateFile, ReadFile, WriteFile, etc)
    for Sealevel synchronous serial products. SeaMAC supports many popular protocols
    including HDLC/SDLC and various bisync, monosync, and raw (bit-shifter) modes.


Requirements
============
    1. Sealevel Systems synchronous serial hardware.
    2. 32-bit or 64-bit Microsoft Windows 7, 10 or 11
        NOTE: Windows 7 requires the following additional updates
        a. Service Pack 1 - https://support.microsoft.com/en-us/help/15090/windows-7-install-service-pack-1-sp1
        b. KB2685811 - KMDF v1.11 - https://support.microsoft.com/en-us/kb/2685811
        c. KB3033929 - SHA-2 Support - https://support.microsoft.com/en-us/kb/3033929
    3. Microsoft .NET Framework v4.6 or later.
    4. 20MB free hard drive space.


Changes
=======
Version 6.0.21
    1. Driver
        a. Added support for 5402ec
    2. Samples
        a. Added support for 5402ec
    3. Utilities
        a. SeaMAC Configuration Utility v1.2.1.0
            - Added support for 5402ec
        b. WinSSD v3.4.2.5
            - Fix broken "auto-calculate" checkbox on the Sync comm settings dialog
            - Fix crash if Windows reports a Microsoft error message containing a percent sign
            - Removed some innocuous logging from the Error display (Port Information tab).
            - Fixed garbled version numbers shown in the About WinSSD dialog box when the program file WinSSD.exe is renamed.
            - Fixes miscounting of sync losses in the BERT tab. Formerly, every 3rd bit
              error would increment the sync loss count even if sync loss did not occur.
            - Removes a 4 second limit on timeouts entered on the Port Information tab. This
              affected the two 'Timeout Constant' fields.
            - Reception of SDLC aborts now get reported in the Port Information tab's
              error box as aborts, rather than the generic "No description available".
    4. Help file
        a. Clarified the behavior of CrcPresetOnes
        b. Updated link to MSDN so it now points to Microsoft Learn
        c. Several clarifications on the Receiving with a SeaMAC device introduction page
        d. The receive & transmit introduction pages were made into standalone pages.
           They were formerly visible only when selecting their parent folders.


Known Issues
============
    1. [FM0/FM1 + 5402ec] The 5402ec is sometimes unable to receive data when opening a port configured for FM0 or FM1. If this occurs, closing and reopening the port should allow the port to begin receiving data. (#687)
    2. [CharacterSyncNAH + 5402ec] The 5402ec may read idle characters and/or sync characters at the start of a message when using Idle Mark. This can be partially mitigated by using Idle Sync. (#694)
    3. Windows 7 requires the following additional updates
        a. Service Pack 1 - https://support.microsoft.com/en-us/help/15090/windows-7-install-service-pack-1-sp1
        b. KB2685811 - KMDF v1.11 - https://support.microsoft.com/en-us/kb/2685811
        c. KB3033929 - SHA-2 Support - https://support.microsoft.com/en-us/kb/3033929
    4. Async mode prevents data rates higher than 115200 from being configured
    5. Z16C32 type devices (5101, 5104, etc.) previously ignored Write Timeout values
        a. Insufficient Write Timeout values can cause dropped data or application hangs
        b. This is especially evident in WinSSD when WriteTimeout = 0
        c. User code may need to be modified to set the WriteTimeoutConstant to an appropriate value
    6. On Windows 7, driver installation requires the user to accept a warning message because Microsoft no longer allows cross-certificate signing.
    7. The driver will not install on Windows 8.1 due to the above issue.


Technical Support
=================
Sealevel Systems Inc. technical support is available Monday through Friday 8 A.M. to 5 P.M.
Eastern Time at (864) 843-4343. Support is also available via email at support@sealevel.com.
Please refer to our website at www.sealevel.com for additional product information, software
updates, and current manuals for our products.