This is a general question, i'm used to using PIC's, and AVR's and not really 8051's. Do most people set the interrupts to another bank with 'using' and leave the rest of the code with the default. Just after some experienced users guidelines. Also we have an 8051 ASIC with 128k code and ram, 2 SPI's etc. I was looking at defining the resources so the compiler knows about this stuff. I'm a little confused about how the compiler would treat it. ie the 128k data is internal to the ASIC but does the compiler still have to treat it as external? thanks David