I had an old program that was written with IAR C Compiler V5.21B Released 06/Nov/97. The code need to be modified, so i purchase the lastest verison of IAR C compiler. The New IAR C compiler, created an larger output file which would not fit in my target. I was forced to uses the old version of the compiler.
I did also attempt to convert the code to work with Keil. I was not sucessful in accomplishing the conversion. However, From what i remember, the IAR and Keil number there C interrupts differently. You should double check that your Interrupt routines are getting placed at the correct vectors.