I am trying to replace an obsolete TSM5055 display. This display basically has a 35bit shift register in it something like the MM5451. I would like to replace this with a hcs08 variant (SE8) and 4 7segment displays. I think i can display the data to the 7segment displays once I capture the data. What I am needing help with is capturing the data that is sent to it. The TSM5055 has an enable line, data line and clock line. I have tried using the clock line to trigger a KBInterrupt and capture the data pin. I have pieced together pieces of ASM code I have gleaned from other people but the micro keeps resetting in the debugger saying illegal something or other. I am not at my test bench right now. Has anyone done this type of thing before and could share some code. I do not know C and am a beginner in ASM.
Thank you for taking the time to read this,