Datapath

Write the RTN for the TRAP, JSR, JMP, and JSRR instructions.

List all the control signals needed to make each instruction happen.

Schematic

What is not shown on page 81 of your book that you need to know about?

Jump Distances

What is the range of addresses you can jump to using the JSR instruction? What is the range of addresses you can jump to using the JSRR instruction? What is the range of addresses you can jump to using the JMP instruction? What is the range of addresses you can jump to using the BR instruction? What is the range of addresses you can jump to using the TRAP instruction?

TRAP

How many trap routines can the LC-3 theoretically have? Why?

How many unused bits are there in the TRAP instruction? What might we use these extra bits for? What are the consequences of choosing to do this?

Which instructions offer different addressing modes via a flag bit? What kind of extra calculations/logic are needed to accomplish such instructions?

What's the difference between JSRR R6 and JMP R6?