4-instruct - Notation used Decimal number: 10 Hex number:...

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Notation used Decimal number: 10 Hex number: $10 Binary number : %10 Motorola 68HC11 Microcontroller 8-bit wide data bus 16-bit wide address bus 64K memory cells addressable Address range: $0000 - $FFFF Divide memory into 256 byte pages: page number = MSB of address Page 0: $0000 - $00FF Page 1: $0100 – 01FF Page 255: $FF00 - $FFFF
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Programming model Processor (registers) 8 bits A 8 bits B 2 bytes (A:B) D (virtual, not real) 2 bytes X 2 bytes Y 2 bytes SP (stack pointer) 2 bytes PC 5 bytes IR 8 bits Condition code (flags) data registers address Registers (pointers) Memory $0000 $FFFF $B210 $B211 $C1 $35
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Languages Machine Language instruction number code (bytes in memory) $BB, $C2, $00 Disassembler translates number codes into mnemonics Assembly Language Instruction mnemonics Program source code ADDA $C200 Assembler translates mnemonics into machine language See Book Appendix for assembler/disassembler ( get very familiar with it; you will use it in the exams )
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Example $C200 $C201 $C202 $BB $C2 $10 $C210 $55 PC $C200 $02 A IR IR IR PC A After execution: 1. Fetch Phase 2. Execution Phase
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Addressing Modes Effective address: address that processor puts onto address bus to load/store DATA item from/to memory Addressing mode: determines how to obtain effective address 68HC11 Addressing modes: 1. Extended Addressing 2. Direct addressing 3. Inherent Addressing 4. Immediate Addressing 5. Indexed Addressing 6. Relative Addressing
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1. Extended Addressing Mode EA = ADDA $C210 address range: 2. Direct Addressing Mode EA = ADDA $C2 address range:
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3. Inherent Addressing Mode No EA to be generated; data in processor, not in memory; or data not needed ABA → address range: 4. Immediate Addressing Mode No EA to be generated; ADDA #$C2 BE CAREFUL: ADDA #$C2 ADDA $C2
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5. Indexed Addressing Mode Uses index registers X or Y as a base address
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This note was uploaded on 09/05/2011 for the course CS 3280 taught by Professor Michael during the Spring '09 term at Missouri (Mizzou).

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4-instruct - Notation used Decimal number: 10 Hex number:...

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