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Radius Rocket disabled MMU... anyone knows why?

Posted by: GeekDot on 2020-06-24 23:34:38 Hey gang, After many moons of waiting on my todo-stack, I finally repaired my Radius Rocket. Runs fine and all... ..but there's one strange thing I came about when doing nastier things than running MacBench: It claims not having an MMU (while the installed 68040/25 certainly has one) - the 'mmu ' Gestalt return-code is empty. I'm not the first one stumbling across this, like this guy in 1999... and it looks like there are some more 040 accelerators not providing MMU functionality. A quick measurement showed they're asserting /MDIS ("MMU disable", pin S6, pulled high)... anybody every heard why they did that?  I was under the impression that a Rocket is a completely "sandboxed" Q9x0 minus I/O and own bus.

Posted by: Trash80toHP_Mini on 2020-06-25 01:32:09 That is a strange one. With full RAM loadout support on board, PMMU might not have been required a/o interfered with Appletalk over NuBus? Since it was intended for use in multiples along with the Host board under RocketShare. I'm not sure where paged memory might be supported, but I can imagine any number of ways support might bomb the system. The accelerators listed in you link would likely have similar conflicts? ________________________________________________________________________________ From the RAMDoubler 1.6.2A Updater Read Me: Accelerators that do not support Apple's Virtual Memory are not compatible with RAM Doubler.  These accelerators which lack a MMU (M=emory Management Unit) include: - Radius Rocket - Fusion Data System's TokaMac - Mobius Speedster 040 - Applied Engineering Transwarp - MicroMac Carrera Similarly, non-accelerator hardware add-ons that are not compatible with Apple virtual memory may have problems with RAM Doubler as = well; all third-party PowerBook display cards, notably the Envisio display adapters, are not compatible with RAM Doubler. ________________________________________________________________________________

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