PC and Mac Cisco 675 External Modem Download Instructions The instructions will assist you in upgrading your Cisco 675 modem to CBOS v2.4.6 Please select the personal computer operating system you use: Click here for Windows® 95, Windows 98, Windows NT, Windows 2000, Windows ME, or Windows XP. Click here for Macintosh® 8.01 (or higher). Cisco® is a registered trademark of Cisco Systems Incorporation. Windows® is a registered trademark of the Microsoft Corporation.