© 2000 Scenix Semiconductor, Inc. All rights reserved. 35 SX User’s Manual Rev. 3.1 www.scenix.com Chapter 2 Architecture Upon reset, the MODE register is initialized to 0Fh for the SX18/20/28AC and SX18/20/28AC75 or
to 1Fh  for  the  SX48/52BD.  This  makes  the  port  direction  registers  write-accessible to  the  “MOV
!rx,W”  instructions.  In  order  to  access  the  other  port  control  registers,  you  first  need  to  write  the
appropriate value into the MODE register, as indicated in Table 2-4 for the SX18/20/28AC and SX18/
20/28AC75 or in Table 2-5 for the SX48/52BD. MODE register values not listed in the tables are
reserved for future expansion. Table 2-4  MODE Register Settings for SX18/20/28AC and SX18/20/28AC75 MODE Reg. Register Written by mov !RA,W Register Written by mov !RB,W Register Written by mov !RC,W X8h Exchange CMP_B X9h Exchange WKPND_B XAh WKED_B XBh WKEN_B XCh ST_B ST_C XDh LVL_A LVL_B LVL_C XEh PLP_A PLP_B PLP_C XFh RA Direction RB Direction RC Direction