AN00015.TXT

Advanced Communication Board Developer's Toolkit 1995


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Subject: Migrating to a higher speed Z85230 ESCC.


For ACB applications that require higher data rates, the standard ESCC
may be upgraded to a higher speed Z85230 ESCC. For details on fully exploiting 
the enhanced versions of the SCC, please refer to the Zilog SCC User Manual.

A new write register is added to the Z85230 ESCC. This register is called
Write Register 7 Prime or WR7'. To access this register, set bit D0 in Write
Register 15. When this bit is set, an access to Write Register 7, will 
actually access Write Register 7 Prime. In the initialization array,
program WR7' to 0 or 10 hex. Additional bits may need to be set depending the
application. Once WR7' has been programmed, reset bit D0 in Write Register
15 and program WR7 as normal.