Writing Device Drivers


Many chips specify that they can be accessed only at specified intervals. For example, the Zilog Z8530 SCC has a "write recovery time" of 1.6 microseconds. This means that a delay must be enforced with drv_usecwait(9F) when writing characters with an 8530. In some instances, it is unclear what delays are needed; in such cases, they must be determined empirically.