lecture06 (JohnPaul Valentino's conflicted copy 2011-11-13)

lecture06 (JohnPaul Valentino's conflicted copy 2011-11-13)...

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Jie Hu, ECE/NJIT, ECE252 L06-Inst. ECE252 Microprocessors Spring 2011 Lecture 06: 68000 Instruction Set Jie Hu http://web.njit.edu/~jhu/ece252/002
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Jie Hu, ECE/NJIT, ECE252 L06-Inst. Block Diagram of Macintosh 512K Motherboard Processor 68000 I/O Interface 6522 Real- time clock Serial I/O 8530 Floppy disk controller System ROM RAM buffers and Mux PAL decoders Dynamic RAM 512KB Sound logic Video logic Speaker Video display Control signals Modem Printer Mouse Keyboard System bus Disk drive
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Jie Hu, ECE/NJIT, ECE252 L06-Inst. Review of Last Lecture Addressing Modes total 14 addressing modes immediate, short immediate data register direct, address register direct memory addressing Implied addressing
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Jie Hu, ECE/NJIT, ECE252 L06-Inst. Today’s Lecture Addressing Modes Absolute short Absolute long Program counter indirect with displacement Program counter indirect with index implied addressing Condition Codes X: the extend flag, N: the negative flag, Z: the zero flag, V: the overflow flag, C: the carry flag 68000 Instruction Set Data transfer
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Jie Hu, ECE/NJIT, ECE252 L06-Inst. Absolute Short Address Absolute short address: this addressing mode is used to directly access data in two specific ranges of memory, 000000-007FFF and FF8000- FFFFFF . The 16-bit value will be automatically sign extended to 24 bits. Assembler syntax: <xxxx>.W, <xxxx> 16 Examples: MOVE.B $3C00, D1 ;EA=$003C00 MOVE.B $9AE0, D2 ;EA=$FF9AE0 3C 09 BA Data Memory Address FF9ADF FF9AE0 FF9AE1 FF9AE2 00FF9AE0 1234FEDC 1234FE09 Old D2 New D2 Easy68K will automatically use absolute long addressing and encode the address as $00009AE0. Forcing the assembler to use absolute short addressing by using .W as: MOVE.B $9AE0.W,D2, is NOT well supported by Easy68K
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Jie Hu, ECE/NJIT, ECE252 L06-Inst. Absolute Long Address Absolute long address: the full 24-bit value directly gives the memory address of the operand. There is no sign extension. Addressing space, 000000-FFFFFF. Assembler syntax: <xxxxxx>.L, <xxxxxx> 24 Examples: MOVE.B $2E000, D0 3C 09 BA Data Memory Address 02DFFF 02E000 02E001 02E002 0002E000 1234FEDC 1234FE09 Old D0 New D0
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ECE252 L06-Inst. Program Counter with Displacement Program counter with displacement: the address is formed by adding a signed 16-bit displacement to the program counter (PC). 68000 uses this addressing mode to implement branch instructions. It can be also used to access the data. Assembler syntax: d 16 (PC) Example: MOVE.B DATA(PC), D4 DATA is a label or the effective address . The assembler calculate the displacement as #DATA-PC for the binary code. Notice that PC here has been increased by
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This note was uploaded on 03/29/2012 for the course ECE 252 taught by Professor Rosenstark during the Spring '99 term at NJIT.

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lecture06 (JohnPaul Valentino's conflicted copy 2011-11-13)...

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