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68k address registers

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I was not able to find this information in the 68k Programmer reference manual , but it could be because I'm not sure what to look for.

Here is the instruction format for the 68k ADD opcode.

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Bits 0-2 and 9-11 indicate registers. What are the binary representations of 68k registers? Are they “addresses”?

Yes, I know that I can write a 68k build program and debug it to find this information. I am looking for a link. Thanks!

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See 2.1, “Format Instructions”:

The instruction defines the function to be performed with the operation code, and determines the location of each operand. The instructions determine the location of the operand according to the specification , the instruction register field contains the register number ; at the effective address, the effective instruction address field contains addressing mode information; or through an implicit reference, the definition of an instruction involves the use of specific registers. (highlighted by me)

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They probably refer to the An and Dn registers listed in Figure 1-1, page 1-2 of the manual that you linked.

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Three bits indicate the address register number, from 0 (bit: 0-0-0) to 7 (bit: 1-1-1). But in general, you can let the assembler worry about it. Hope this helps, Dave

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