How to Install Software for TN3270 for Mac OS X 10.15 - 14.x Sonoma


Follow these steps to install software for TN3270 on your Mac computer. TN3270 is a terminal emulator used for connecting to mainframe applications, such as IFIS, ISIS, and PPS.

Critical Concepts

Steps to Take

  1. Download the TN3270 client software at
  2. Choose: Mocha TN3270 for macOS 3.1 (OS X 10.15 - 14.x)
  3. Open the downloaded file
  4. Drag the TN3270 icon to the Applications folder
  5. Run TN3270 from the Applications folder
  6. Once TN3270 is open, follow the instructions below to create a session file.
    1. Open TN3270 and close any default window that comes up. Click Cancel.
    2. Click on File then New Session
    3. Enter the host name:
    4. Enter the window title: adcom.
    5. Click the Special box.
    6. In the Port field, enter 1023, and choose SSL for Security.
    7. Select SSL/ TLS Default
    8. Select Negotiate SSL
    9. Click on OK.
    10. Click on Open Connection, and verify the connection works.
    11. Once verified, click File then Save Settings As…, and save settings file to an appropriate location.
    12. If you can't connect, open the Special box, verify the port number, and then try to connect again. To eliminate confusion, overwrite the old file.
      screenshot of Mac fields to load SnowLeopard

If you still have questions or need additional assistance, please contact the ITS Service Desk. You can call us at (858) 246-4357, email us at, or submit a ticket at