(r) this line goes to the ROM only.
(s) this line is Shared between the ROM, MMC/chip, and Nintendo
(n) this line connects to the NES cart edge only, and not the ROM
(w) this line connects to the WRAM only and nowhere else
MMC3 Chip: (44 pin QFP) [Made by Kevin Horton (
[email protected])]
----------
Comes in three types: 'MMC3A', 'MMC3B', and 'MMC3C'
33 23
| |
.-------.
34-| |-22
| MMC3B |
44-| |-12
\-------'
| |
1 11
Pin# Function Pin# Function
---- -------- ---- --------
1 - ??? *1 23 - PRG A17 (r)
2 - CHR A10 (r) 24 - PRG A13 (n)
3 - CHR A12 (n) 25 - PRG A18 (r)
4 - CHR A11 (n) 26 - PRG /CE (r)
5 - CHR A10 (n) 27 - +5V
6 - GND 28 - GND
7 - CHR A13 (r) 29 - M2
8 - CHR A14 (r) 30 - WRAM /CE (w)
9 - CHR A12 (r) 31 - PRG D7 (s)
10 - CIRAM A10 (n)*32 - PRG A0 (s)
11 - CHR A15 (r) 33 - PRG D6 (s)
12 - CHR A17 (r) 34 - PRG D0 (s)
13 - /IRQ 35 - PRG D5 (s)
14 - PRG /CE (n) 36 - PRG D1 (s)
15 - GND 37 - PRG D4 (s)
16 - ??? *2 38 - PRG D2 (s)
17 - PRG R/W (n) 39 - PRG D3 (s)
18 - PRG A15 (r) 40 - GND
19 - PRG A13 (r) 41 - WRAM CE (w)
20 - PRG A14 (n) 42 - WRAM /WE (w)
21 - PRG A16 (r) 43 - CHR A11 (r)
22 - PRG A14 (r) 44 - CHR A16 (r)
NOTES:
*: On Gauntlet, this is unused.
*1: PINS 1 & 2. Sometimes these are connected together. If they are not,
pin 1 is left floating.
*2: PIN 16. Sometimes this is connected to ground. Other times it is left
floating.
It seems that pins 1,2 & 16 are related; pins 1 & 2 are shorted as are pins
15 and 16. Or else pisn 1 & 2 are left open as well as 15 & 16. I've never
seen say, pins 1 & 2 shorted while pin 16 was open or vice-versa. I suspect
they relate to extra RAM in the CHR section.
