Hi, The literature I'm reading suggests that I can specify the number of bits a certain data type must occupy, and that I can possibly store several of these packed variables into the same byte for reduced storage space. typedef struct{ unsigned int a: 4; unsigned char b: 2; } my_type; I tried the above but it just truncates the values assigned and stores them in separate two byte wide and 1 byte wide spaces respectively. What's the trick? Regards, Murray R. Van Luyn.