EE345 Midterm Review

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EE345 Midterm Review

• Dr. Jane Dong

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Outline

• 6811 Architecture
• Review of Addressing modes
• Review of Instructions
• Problem solving from Hw3
• Exercise write a program

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A Simple Architecture
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M68HC11 Architecture (1)

• CPU registers

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Memory map in M68HC11

• M68HC11 has 16 bit address bus
• And 8-bit data bus
• has memory locations
• Each location hold 8-bit word
• Not all locations can be used
• Most useful regions in EE345
• 256 byte RAM staring from 0000
• Used for store variables, etc.
• 8K ROM starting from e000
• Used for store program

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Addressing mode (1)

• What is addressing mode?
• The method to reference data in memory or in
  instruction
• The same instruction may have different
  addressing mode
• How M68HC11 distinguish among the addressing
  modes?
• Different addressing modes? different Opcode in
  machine code
• Example
• LDAA 64 load an immediate value
• LDAA 0001 load from memory address 0001
• LDAA 4, X load from memory address X4

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Addressing mode (2)

• Immediate Addressing
• Direct Addressing
• Extended Addressing
• Inherent Addressing
• Index addressing
• Relative addressing

Example What addressing modes are used? ADDA
100 ADDA 0001 SUBB 2, X
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Instruction review

• Your good friend Instruction set table

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Example

• CLRA
• LDAA 10
• LDAB 01
• ABA
• STAA 02
• COM 03
• LDX 0
• STD 2, X