My Target has 256kB FLASH at CS0 and 256kB RAM at CS1. The Monitor-Code is at 3C000H and the Monitor-Data is at 3E000H. The Version of RTX-166 : V4.01 The Keil Developmet Tools Release : 05.2001 The CPU : C167CR-LM My Problems are : - The functions in the modul <start167.a66> delete the wrong memory if the switch "CLR_MEMORY" is set. - The function os_start_system() return FFFFH in R4 or it doesn't come back. My Question is how must the Monitor be configured to works correct, how must the RTX-166 be configured to start correctly and how must I the CLASSES NCODE, ICODE, FDATA, ... adjust. Best regards Reinhard Woeber