Apple IIgs #55
Avoiding ClrHeartBeat

Written by Matt Deatherage (July 1989)

This Technical Note lists changes to the description for ClrHeartBeat. This information supersedes the description in the Apple IIGS Toolbox Reference Manual.

The Apple IIGS Toolbox Reference Manual gives the following cautionary note in the description for the call ClrHeartBeat:

"A desk accessory may have installed tasks in the Heartbeat Interrupt Task queue. If you make a ClrHeartBeat call, you will remove those tasks. Therefore, under normal circumstances you should not make this call."

This isn't rude enough to get the point across to some people, so we'll try again:

The Heartbeat Interrupt Task queue does not belong to the application. Different portions of System Software can, and will, install Heartbeat Tasks. If these tasks are removed, anything from a system crash to media corruption may result. Nothing but System Software should make this call.

Further Reference

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