CX22011,Top sales CX22011,CX22011 DATASHEET

Note that a problem can occur if a DMA request occurs on
an unmasked channel while the 82C37A is being pro-
grammed. For instance, the CPU may be starting to repro-
gram the two byte Address register of channel l when
channel l receives a DMA request. If the 82C37A is enabled
(bit 2 in the Command register is 0), and channel l is
unmasked, a DMA service will occur after only one byte of
the Address register has been reprogrammed. This condi-
tion can be avoided by disabling the controller (setting bit 2
in the Command register) or masking the channel before
programming any of its registers. Once the programming is
complete, the controller can be enabled/unmasked.
CX22011   datasheet