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Old 05 August 2014, 23:19   #13
Toni Wilen
WinUAE developer
Join Date: Aug 2001
Location: Hämeenlinna/Finland
Age: 43
Posts: 20,646
Originally Posted by phx View Post
Ok, and clearing bit 0 causes a strange PPC->M68k level 2 interrupt?
No. Nothing happens, it probably causes PPC interrupt but that can't be fully correct either because it still won't fix PowerUP.

I am quite sure this bit only does something when PPC is active.

But it also unlocks REG_SHADOW. I verified that. Otherwise I don't understand why you unlock the flash for rebooting the system.
Do you know at which address the flash is written after that.
Bad explanation, sorry. It unlocks REG_SHADOW and REG_SHADOW bit 2 is flash write-enable bit. (CSMK3/CSPPC only)

Remember that "write-enable" only means flash chip sees write accesses, flash chip still needs flash write or erase access sequence to actually write anything. Just check any compatible flash chip datasheet to see how programming works. (29F010 or 29F040 for example)

BPPC does not have flash enable bit here, it has separate registers (as I said above)

Also because BPPC has 512k flash (vs 128k in Cyberstorms), it has extra flash mapping, if SCSI is disabled (P5_SCSI_RESET is cleared), flash also appear at $f40000-$f5ffff, this space is mostly used, very tiny part at $f5c000 is used for config saving only. Apparently last 128k of flash is always unmapped. At least flash updater only writes first 384k of flash.

About which register are you talking here? REG_IRQ = REG_INT ?
I forgot I renamed some registers because they looked wrong
My REG_IRQ = f60008.

Can't follow here. Bit 0 of which register?
REG_LOCK, the register with only one settable/clearable bit.

Bit 0 and 3? Wasn't bit 0 your mystery cause-interrupt strobe? Then that wouldn't work on BPPC? And writing has no effect at all?
I meant bit 0 is the mystery one and then BPPC has extra bonus bit, bit 3 set to one as an BPPC identification bit. Flash updater says you don't have BPPC if this bit is not set. (This is always cleared on CSMK3/CSPPC)

Wow! Never heard of these registers. Write any value to $f60093? And writing a value != $42 to $f60092 doesn't write-protect the flash again?
Flasher utility (and flash rom boot menu settings flasher) uses $42 for both. Can't confirm, don't have hardware.
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