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Re: Adding 1MByte RAM to MMC5 cart for infidelity's project
Posted: Tue Nov 26, 2019 9:57 pm
by aquasnake
lidnariq wrote: ↑Tue Nov 26, 2019 9:38 pm
aquasnake wrote: ↑Tue Nov 26, 2019 9:34 pm
does Infidelity access $5113.bit[7] to enable single bank of PRG-RAM at $6000-$7FFF just like standard MMC5,
$5113.bit[7] doesn't exist. It is impossible to enable ROM in the $6000-$7FFF range, due to how the MMC5 handles PRG-ROM and PRG-RAM banking. (For the same reason, it is impossible to enable RAM in the $E000-$FFFF range, and $5117.bit[7] doesn't exist either)
or access $5001.bit[7] to enable all banks of PRG-RAM at $6000-$DFFF like MMC5+?
... why on earth is that control a useful thing to add?
$6000-$7FFF can be also used as either PROM or PRAM just controlled by $5113.bit[7], to be used as PROM, its behavior is more like some Kaiser's unique carts. so MMC5 has the ability to emulate other mappers in some cases
Re: Adding 1MByte RAM to MMC5 cart for infidelity's project
Posted: Tue Nov 26, 2019 10:05 pm
by Ben Boldt
infidelity is using only the address space $6000-7FFF for PRG-RAM, and $8000-FFFF for ROM.
lidnariq wrote: ↑Tue Nov 26, 2019 9:33 pm
Ben Boldt wrote: ↑Tue Nov 26, 2019 9:14 pm
But I thought the MMC5 latches the data bus for writes on the rising edge of M2?? Should I do an M2 falling edge trigger for this? I
always get confused with the clock edges of the NES.
Rising edge ≈ address bus and R/W are stable
Falling edge ≈ data bus is stable (both for reads and writes)
Not clear why the data bus isn't valid on both edges on writes, but it's not.
I recently measured this:
nesdevforum:post #244126
Okay, very interesting. I will be sure to do a falling edge trigger then.
Re: Adding 1MByte RAM to MMC5 cart for infidelity's project
Posted: Tue Nov 26, 2019 10:15 pm
by lidnariq
aquasnake wrote: ↑Tue Nov 26, 2019 9:57 pm
$6000-$7FFF can be also used as either PROM or PRAM just controlled by $5113.bit[7], to be used as PROM, its behavior is more like some Kaiser's unique carts. so MMC5 has the ability to emulate other mappers in some cases
No. No it does not. No it cannot. The real physical MMC5 does not support this behavior, and any emulator that lets you map ROM in the $6000 bank is wrong.
Re: Adding 1MByte RAM to MMC5 cart for infidelity's project
Posted: Sat Nov 30, 2019 4:14 pm
by Ben Boldt
lidnariq wrote: ↑Mon Nov 25, 2019 8:46 pm
That said, there aren't any registers in the $53xx range, right? So shouldn't need to care about A9?
Sorry I missed this, skipping A9 right away would save me the gate that is just inverting CPU R/W. It might also allow me to use a more common quad 2-input chip or something. Very useful to consider, thanks.
Re: Adding 1MByte RAM to MMC5 cart for infidelity's project
Posted: Tue Feb 04, 2020 1:07 pm
by aquasnake
the chr-rom of infidelity's "super mario all-stars" had better be decresed to 512K if possible, that would be easy to make a repro without an original MMC5 chip, i wish to see it one day