I have assembled a simple scheme, my eval board: 164CI, address latch, 32kB RAM on CS0. Then I put cristall in BSL mode and downloaded Keil user167 monitor. Next monitor dowloaded my program as follows: #include <reg164.h> sbit tpindir = DP1L^0; sbit testpin = P1L^0; void main (void) { tpindir = 1; while(1) testpin = !testpin; } Everything's running ok - only in debbuger. Pin state doesn't change. Does enyone has idea - why? Roman. Russia.