Sunday, March 15, 2009

Motorola 68000

The 68000 microprocessor comprises:
- 8 data registers namely D0 - D7
- Address registers, A0 - A7
- Program counter (PC) & Status register (SR).

Data registers
Data register is used to hold data temporarily for the use in processing. Each registers can be accessed for byte operands (0-7), word operands (0-15 bits) or long-word operands (0-31 bits).
Function: Used to store information within the 68k uP itself

Address registers
Address register are not provided for storage of data for processing. Instead, they are meant to store address information. Although every registers contain 32 bits, only the lower 24 bits are used to access memory. Therefore, the address range is 224 (16M) byte.
Function: Used to store the location where data can be founded outside the processor. Ex: external memory chip. A7 usually is used to execute subroutine

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