Hello, 1) I want to place assembly code in my C code. The problem with using SRC is that I would have to rename the file MyAsm.SRC to MyAsm.A51 and then (remove C code from project) include A51 code in the project... before finally recompiling the whole project. Is there any way to just add assembly code without using SRC? What about the '__asm' keyword? Where do I get more info on this? 2) The Cx51 User Manual (Pg124) states that the Interrupt function will save SFR, ACC, B, DPL, DPH etc 'when required' to stack (and later pop it). How do I disable this feature so I can manually do the PUSHing and POPing? If this is not possible then is it possible to instruct Keil to 'save all' registers regardless of need? Regards, KC
Will it make any difference if I write the ISR totally in Assembly? if you do that EVERYTHING including register saves (do not forget the PSW) is up to you, nothing is automatic. Usually a bank swotch ("using") is a better solution if you use several registers. Erik