Exam 1 Review

M68000 Topics

• Converting ASCII representation of digits into corresponding values

• The use of the following assembler directives: EQU, DS, DC, ORG, and END.

• TRAP #14 Tutor Functions

  Remember that the function number is passed to the trap function through the lower word of data register D7.

  Number	Function	Argument Registers
  247	Input Character	D0
  248	Output Character	D0
  243	Print string	A5-string start address A6-string end address + 1
  228	Exit to Tutor	None

• Addressing Modes

  Given the contents of the data registers, address registers, and memory and a specific instruction, be able to:

  1. name the addressing mode employed in the source operand
  2. write the RTL equivalent of the instruction, paying attention to the operation (e.g., MOVE, SUB, etc.) and the operand size (i.e., .B, .W, and .L extensions)
  3. give the final contents of the destination register/memory location
  (See Exercise 3.4)

• Use of addressing modes to access data.

• DUART read and write routines (ref)

• Program flow control using CMP and Bcc.

  Note that CMP instruction do not always need to precede branch instructions.

MC68HC11 Topics

• Subroutines usage including
  • use of JSR and RTS instructions
  • their interaction with the stack
  • preserving register contents to provide transparency to the calling routine
  • argument passing through registers

• Implementation of while...do and do...until loops using an index register for a counter (generalization of for loops) (See Exercises 5.1 and 5.2)

General Topics

• RTL <-> Instruction conversions for both processors

• Identification of structures used in program routines

• Comparison of 68000 and HC11 based on the following criteria
  • Programmer's model
  • Word size
  • Instruction set
  • Addressing modes
  • Boards space required for implementation
  • Control or data processing orientationl
  • Peripheral architecture

• General methods for testing, setting, clearing, and complementing specific bits in a register. (Consider and, or, and xor operations.)