CS 2734 Computer Organization II

In this lecture we talk about the basic principles of a two-pass assembler and will apply these principles to develop an assembler for a simple machine called the MAC-1.

• Basic functions of a two-pass assembler:
  • Pass I: Build up a symbol table.
  • Pass II: Produce assembled output.

• Properties of the MAC-1:
  • It is a one register machine which has a stack.
  • Each addressable unit of memory is 16 bits.
  • An instruction takes up 16 bits.
  • Addresses take up 12 bits.

• Try to assemble the following sample program