Game Pak

Nintendo 64 Game Pak (part number NUS-006) is the brand name of the consumer ROM cartridge product that stores game data for the Nintendo 64, released in 1996. As with Nintendo's previous consoles, the Game Pak's design tradeoffs were intended to achieve maximal system speed and minimal base console cost—with a lesser storage space and a higher unit cost per game. Integrating a CD-ROM drive, with its expensive and slow moving parts, would have drastically increased the console's base price and reduced its performance.

See ROM header for the standard contents of the header of the ROM within the Game Pak.

	Pin Cart Solder Side	Pin Cart Component Side
Ground	1	26	Ground
Ground	2	27	Ground
AD15	3	28	AD0
AD14	4	29	AD1
AD13	5	30	AD2
Ground	6	31	Ground
AD12	7	32	AD3
/Write???	8	33	ALE_L
3.3V	9	34	3.3V
/Read???	10	35	ALE_H
AD11	11	36	AD4
AD10	12	37	AD5
12V	13	38	12V
12V	14	39	12V
AD9	15	40	AD6
AD8	16	41	AD7
3.3V	17	42	3.3V
CIC_DATA1	18	43	CIC_DATA2
1.95 MHz CLK	19	44	INT1
/COLD_RESET	20	45	NMI
S_DAT	21	46	Video Sync
Ground	22	47	Ground
Ground	23	48	Ground
Left Audio	24	49	Right Audio
Ground	25	50	Ground

The above table is merged from multiple sources and personal knowledge

Pin 19 is 1.95 MHz Clock from the PIF - 62.5 MHz /32

While the use of the Read and Write contacts seems obvious, it's actually not 100% confirmed.

FACTS:

Board  NUS-06A-01  (fully visually confirmable)

Pin 8 (aka write) is routed directly to the save IC, no other stops.

Pin 10 (aka read) is routed to 2 pins of the Game ROM and 1 pin on the save IC

Board NUS-07A-01

Pin 8 (aka write) is routed to 1 pin on the Game ROM (visually confirmable) and 1 pin on the save IC (VM continuity check)

Pin 10 (aka read) is routed to 2 pins of the Game ROM  (visually confirmable) and 1 pin on the save IC (VM Continuity check)

References:

http://n64.icequake.net/mirror/www.crazynation.org/N64/

http://www.acidmods.com/RDC/NINTENDO/N64/N64%20NUS-CPU-03-04.pdf