Hell, yet another interesting damn pirate cartridge of MMC3! :
Here is the pinout of the unknown chip :
Any idea what it can be?!
It seems TTLs are responsible for these pins :
IRQ
CIRAM
CHR A16
And the whole circuit lacks these unnecessary pins comparing to a real MMC3 :
D6
D7
CHR A17
PRG A17
PRG A18
WRAM +CE
WRAM /CE
WRAM /WE
Downtown - Nekketsu Monogatari with TTLs!
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1. NO BLATANT PIRACY. This includes reproducing homebrew less than 10 years old, with the exception of free software.
2. No advertising your reproductions, with the exception of free software.
3. Be nice. See RFC 1855 if you aren't sure what this means.
Re: Downtown - Nekketsu Monogatari with TTLs!
Is it a knockoff Namco 108 clone? That would explain having to implement the MMC3 IRQ (the 4020), the ability to swap left/right pattern tables and $8000/$c000 in PRG (the 74'151), and needing to implement extra bits to get 128 KiB of CHR.
Last edited by lidnariq on Thu Jan 22, 2015 2:16 am, edited 1 time in total.
Re: Downtown - Nekketsu Monogatari with TTLs!
Here is a similar case :
NTDEC8701
NTDEC8701
Re: Downtown - Nekketsu Monogatari with TTLs!
Ok, the 74'259 (addressable 8x1 latch, parallel out)+74'151(1 of 8 multiplexer) together make CHR A16, increasing CHR from the 64 KiB supported by the N108 to 128KiB.
The 74'161 latches the data written to $8000: the register address.
The 74'138 decodes four of the eight registers the MMC3 nominally has. I can definitely allocate for $E000, $8000, and $8001, I'm not really certain what the last one would be. Probably $E001.
The 74'74 both contains the IRQ enable bit and the "IRQ fired" bit. Interestingly, both halves seems to be latching CPU A1, not just a fixed value.
The 74'02 both generates CHR/CE with NOT(NOR(PPU A13,PPU /RD) and ... something else, I can't see what those traces are doing.
The 74'4020 seems to connect its Q9 bit to the 74'74's 1/CLK input, or an interrupt after 1024 somethings ... probably M2 cycles. (almost exactly 9 scanlines, FWIW)
I can't figure out what the last IC is. Its silkscreening is really hard to see in the photo, but it appears to be connected to CPU D0..D3.
The 74'161 latches the data written to $8000: the register address.
The 74'138 decodes four of the eight registers the MMC3 nominally has. I can definitely allocate for $E000, $8000, and $8001, I'm not really certain what the last one would be. Probably $E001.
The 74'74 both contains the IRQ enable bit and the "IRQ fired" bit. Interestingly, both halves seems to be latching CPU A1, not just a fixed value.
The 74'02 both generates CHR/CE with NOT(NOR(PPU A13,PPU /RD) and ... something else, I can't see what those traces are doing.
The 74'4020 seems to connect its Q9 bit to the 74'74's 1/CLK input, or an interrupt after 1024 somethings ... probably M2 cycles. (almost exactly 9 scanlines, FWIW)
I can't figure out what the last IC is. Its silkscreening is really hard to see in the photo, but it appears to be connected to CPU D0..D3.
Re: Downtown - Nekketsu Monogatari with TTLs!
Does it contain a functional scanline counter?
- mikejmoffitt
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Re: Downtown - Nekketsu Monogatari with TTLs!
Hahah, look at the completely random brand selection on those chips! It's like they wanted to be sure to use one of everyone's chips - I see Signetics, NEC, Mitsubishi, Goldstar, Hitachi, one I can't place, and of course the unlabeled packages.
Re: Downtown - Nekketsu Monogatari with TTLs!
( "M in a rounded box" is Matsushita/Panasonic. )
Re: Downtown - Nekketsu Monogatari with TTLs!
Finally get this CART ROM
This cart IRQ C002 E000 E002
We haven't had any success, IRQ
This cart IRQ C002 E000 E002
We haven't had any success, IRQ