I have an 500+ rev8A, I added the missing 0.5 MB RAM and the U32 to the motherboard. I also have 512 KB in the trapdoor. This results in 1.5 MB chip RAM; but I want to have 1 MB chip RAM and 0.5 MB slow RAM.

How can I arrange for this? That is, for the expansion to be used as slow RAM? What are the right jumper settings (JP2, JP3, JP4A, JP4B, JP7A — no U32) for this configuration?

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    Note I'm not an Amiga expert, but don't understand why someone would want to have slow RAM over chip RAM. AFAIK, slow RAM has the same speed restrictions as chip RAM, but not the benefits (can be used by the chipset) – tofro Sep 27 '18 at 15:30
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    It's the U32 addition that is causing the trapdoor memory to be decoded as CHIP RAM, I think. Without that modification the motherboard RAM should be CHIP RAM and the trapdoor RAM CPU only. – Brian H Sep 27 '18 at 17:59
  • @tofro Rumours are there are badly written games that expect RAM on a given address space. Chip and "slow" are on different addresses so it could be something like that. – pipe Sep 28 '18 at 0:42
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    You want 0.5MB 'slow fast' RAM at C00000-C7FFFF? amigacoding.com/index.php/Amiga_memory_map – Bruce Abbott Sep 28 '18 at 10:10
  • @Bruce, yes exactly. some demos, and games needs memory at C0... – lasertank Sep 28 '18 at 11:02

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