is there a file that i can include with the startupcode in C for a 80c537 or how should it be written. I also need to initialise SPI.
The Infineon 80C537 does not require a special startup code. Just the normal STARTUP.A51 file does the job. Infineon offers an utility called DAvE that is able to generate code for the on-chip peripherals. Take a look to: http://www.keil.com/appnotes/docs/apnt_182.asp. Yes, this is for C166, but it works the same way for 8051 based products.