Re: LAB #2 - PART 1: Address Space

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: : : On the lab sheets we are told: : : : "The UofT68000 board's address space from $200000 to : : : $B00000 is not used. ... To reduce the amount of : : : wiring, you're allowed to use aliasing. That is, : : : instead of locating your register at a specific : : : location, you can allow any address in the range : : : $200000 to $B00000 to access your register." : : : My question is simply whether or not $B00000 is : : : included in the allowable addresses. I would think : : : that it isn't because it can't be differentiated from : : : $BXXXXX without looking at the lower order bits. : : : So the allowable addresses are actually $200000 to : : : $AFFFFF inclusive, right? : : I don't have the 68000 manual with me right now, so I can't : : check if $BXXXXX addresses can be used or not. You are certainly : : safe using the range $200000 to $AFFFFF. : : JC : It turns out that the available address space is actually from $200000 to : $BFFFFF. I saw this in the 68000 Gizmo Board Manual (I don't remember the page : number but it's in there). : This can simplify things a little bit because now only the 3 most significant : bits of the address need to be checked. This can also be a little confusing as : the addresses are usually represented in hexadecimal but the 3 MSbs can only : form octal numbers.

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