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Paul Ghobril
Paul Ghobril
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What is the reason of the particular range of the last 4K block of memory selection in Apple II

Following my previous question on Identifying the functionality of the memory select in Apple II and now that I know that the memory select device is simply an interconnection block. Searching for more, I found the Apple II red book where the memory select is explained with the following figure:

enter image description here

So I represent the interconnection scheme as I got it. For 16K/16K/16k:

enter image description here

For 16K/4K/4K:

enter image description here

Now the question is: why the last 4K block is (6000 - EFFF) and not (8000 - 8FFF)?

Is it related to RAM mirroring, bank-switched ROM or anything else?

What is the reason of the particular range of the last block of memory selection in Apple II

Following my previous question on Identifying the functionality of the memory select in Apple II and now that I know that the memory select device is simply an interconnection block. Searching for more, I found the Apple II red book where the memory select is explained with the following figure:

enter image description here

So I represent the interconnection scheme as I got it. For 16K/16K/16k:

enter image description here

For 16K/4K/4K:

enter image description here

Now the question is: why the last block is (6000 - EFFF) and not (8000 - 8FFF)?

Is it related to RAM mirroring, bank-switched ROM or anything else?

What is the reason of the particular range of the last 4K block of memory selection in Apple II

Following my previous question on Identifying the functionality of the memory select in Apple II and now that I know that the memory select device is simply an interconnection block. Searching for more, I found the Apple II red book where the memory select is explained with the following figure:

enter image description here

So I represent the interconnection scheme as I got it. For 16K/16K/16k:

enter image description here

For 16K/4K/4K:

enter image description here

Now the question is: why the last 4K block is (6000 - EFFF) and not (8000 - 8FFF)?

Is it related to RAM mirroring, bank-switched ROM or anything else?

Source Link
Paul Ghobril
Paul Ghobril
  • 1.1k
  • 1
  • 6
  • 19

What is the reason of the particular range of the last block of memory selection in Apple II

Following my previous question on Identifying the functionality of the memory select in Apple II and now that I know that the memory select device is simply an interconnection block. Searching for more, I found the Apple II red book where the memory select is explained with the following figure:

enter image description here

So I represent the interconnection scheme as I got it. For 16K/16K/16k:

enter image description here

For 16K/4K/4K:

enter image description here

Now the question is: why the last block is (6000 - EFFF) and not (8000 - 8FFF)?

Is it related to RAM mirroring, bank-switched ROM or anything else?