Black Box IC128C-R3 Manual page 19

PC PLUS ADAPTER DUAL SERIAL PCI
Optimum buffer settings depend on your modem
speed, your CPU speed, and the amount of multi-tasking
that occurs while online. For a fast modem and fast CPU
performing few multi-tasking functions, set transmit
triggers low and receive triggers high. If multi-tasking
while online, set transmit triggers higher and receive
triggers lower.
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