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blackjetrock / z80_shield

Z80 Shield project
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Make mega rom emulation compilation conditional #4

Closed derekfountain closed 5 years ago

derekfountain commented 5 years ago

I think we're at a bit of a decision point. Do we continue to make the software support extra features, use cases and weird modes, or do we make it usable and understandable? After 3 days of wondering what it's doing half the time, I'm voting for the latter. :)

This change turns off the ROM emulation in the Mega. i.e. it sets and drives the shield such that the flash chip always supplies the data from the bottom half of the address map. This removes the weird inconsistencies which keep catching me out and making me wonder why the thing has behaved oddly again.

I appreciate the value of letting the Mega supply data so I've left the feature in via conditional compilation. But I think by default we need to simplify. :)

blackjetrock commented 5 years ago

I think I agree. Leaving the code in there means we can easily turn it on again if, for instance, someone want s a PCB that can only trace code and decides to fit no RAM or flash, for instance. There is the overhead of programming the flash, but we had the overhead of embedding the emulated flash code anyway, so no real change.