Power Macintosh 54xx/64xx: Serial Port Communication

With a Power Macintosh 5400 and 6400, I sometimes have trouble communicating with my third-party serial devices. Sometimes the device is not recognized by the system. What should I do?
In some cases, some serial devices may have difficulty communicating with Performa 6360, 54xx, and 64xx series computers. This issue is resolved by installing Mac OS 7.6.1. You cannot just install Mac OS 7.6. The necessary improvements were incorporated exclusively into Mac OS 7.6.1.

If you install Mac OS 7.6.1 and the issue continues, please contact the manufacturer of the device for additional compatibility and troubleshooting information.
Published Date: Feb 18, 2012