The A3000 had a ficker fixer. If you meant that the other later models should have also included it, I agree.

Regarding the MMU, the problem was/is the OS. AmigaOS uses message passing between processes extensively, and those messages often involved passing pointers to structures that the receiver expected to be able to dereference and even writ to in some cases.

I'm on record repeatedly arguing over the years that it would be possible to retrofit at least limited memory protection onto AmigaOS, but it's decidedly not something that'd be simple to do, and most likely you'd need to basically sandbox old apps and create new API's for new apps to do it properly.

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amiga386 an hour ago | parent | next [-]

It would be simple, but somewhat incomplete. It would not look like a virtual memory subsystem where merely accessing an address can allocate physical RAM to it.

The API is already there! AllocMem(, MEMF_PUBLIC) allocates shared memory, otherwise you get private memory.

You can then enforce memory protection around that, but obviously the entire OS is still built on message-passing between tasks where the message itself remains at exactly the same (public) address and isn't copied between private memory spaces, and there's a gentlemens' agreement as to who currently owns it (PutMsg/ReplyMsg)

Software like Enforcer and MuGuardianAngel already checked this, and dinged your program for accessing non-allocated memory.

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smallstepforman 22 minutes ago | parent | prev [-]

With mmu, every app has its own 32bit address space, and the mmu “maps” the app space to physical space. Legacy apps get shared address space, while newer apps get isolated space. To port apps, its only the messaging system that needs rework, and if the system does its magic with same API, transition is invisible. At the end of the day, only the message address space needs to be shared. Sendmessage() behind the scenes remaps mmu addresses. Not impossible, just requires the will to do it.

	▲	vidarh 11 minutes ago \| parent [-]
		The problem with that is that the messaging system permeates everything on the Amiga, so you'd lose basically every app without rework. That might have worked if the Amiga had a growing market share, but at the time this became an option, the Amiga market was already dying. It's not "only" the message address space, as e.g. messages included pointers to a lot of other data structures that'd now either need to be copied or mapped into the receiving process, or the message formats reworked.