MS-Windows, OS/2 and others.When using a modem AX25_MAC requires a very low interrupt latency (see appendix 2) which can not be accomplished when running under Windows, or IBM OS/2 2.0 (although there are a lot of people who find it hard not accept this fact). That is why AX25_MAC will generate an error message if an attempt is made to start AX25_MAC for modem use while running one of these systems. Newer version of Windows may hide the fact that AX25_MAC runs under windows. Then the error message is not displayed, but it will not work nevertheless.
Operating an SCC-Card using these systems is possible. Actually, this works quite well when using 1200 baud under Windows. When using higher baud-rates running SCC cards will also cause problems. Running OS/2 will not work as well as running under Windows, but this was only tested during a short test. I have no idea how well a PAR96, PICPAR or YAM96 modem will work under these systems.
KISS mode works in my setup on both systems up to at least 38400 baud without any problem. The COM ports are fully supported by Windows and OS/2 drivers, which is unfortunately not the case for the SCC cards (which is of course reasonable).
When using other multitasking systems you may find a similar behavior.