On 9/29/2019 7:04 PM, Nejat Dilek wrote: > If it's a cartridge thing I would just use solely IO1 or IO2 space > since it's user's responsibility to choose the compatible hardware > along with compatible software. If that's not the case then a stealthy > approach could be waiting for a correctly timed sequence of writes. I > successfully implemented it in my EasyKernal and IRQHack64 projects. A > short period between two memory accesses to certain address/address > area represents 0, a long period between two memory accesses > represents 1. Hardware is not activated until it gets 24 bit of > information right which is impossible (almost) with the legacy > software. I did this with an AVR part but this can easily be > implemented in vhdl too I guess. It is not a cartridge option, so I think IO1/2 is not a good choice. It is entirely possible that a cart will be inserted at the time this additional memory is accessed. Special timed writes/reads are fine to unlock the register space, but it would not make sense to set all of the registers in this MMU via that mechanism, due to the number of addresses to change and the frequency of changing them. Jim > -- Jim Brain brain_at_jbrain.com www.jbrain.comReceived on 2020-05-29 22:39:00
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