STEP1 [What is N64?] - Chapter 2 Hardware Configuration

2-6 PI (Parallel Interface)

The PI is the 16-bit parallel bus connection the N64 Game Pak or the N64 Disk Drive. The average transfer rate for the Game Pak is about 5 megabytes per second. (The peak performance is about 50 megabytes per second.) The PI uses DMA transfer to transfer information from the Game Pak or N64 Disk Drive to RDRAM.

2-6-1 Devices Connected to the PI

The PI is the DMA engine that connects the following devices with RDRAM.

N64 Game Pak
N64 Disk Drive

*The transfer rate

Game Pak: Average :5MByte/sec
N64 Disk Drive: Maximum :1MByte/sec

*The actual game application is stored in the ROM of the N64 Game Pak. When you use the N64 emulator board you use the RAM (called virtual ROM or RAMROM) of the developmental board. The communication between the host machine and the developmental board is provided through the RAM device on the developmental board.

Figure 2-6-1 N64 Disk Drive and N64 Game Pak Connected to the PI

2-6-2 N64 Game Pak Specification

Mask ROM	: 32M bytes (256M bits)
EPROM	: 4K bits or 16K bits
SRAM(battery backup)	: 256K bits

2-6-3 N64 Disk Drive

Features

Large capacity magnetic disk for changing Character and Data.
Built-in RTC with backup battery for real-time applications.
Doubled RDRAM with the addition of the required Memory Pak which adds another 4 megabytes by 9 bits to N64 main memory.

N64 Disk Specification

Capacity	: About 64.45M bytes
Writable capacity (the RAM part)	: 0 ~ 38.44M bytes
Non-writable capacity (the ROM part)	: 26.01 ~ 64.45M bytes

Store the data that users do not rewrite, such as the game program or the character data, in the ROM part. Store the saved data in the RAM part. An identification number (ID) is written on the Disk to identify each individual Disk when it is shipped from the factory. This ID is used when the Disk must be changed such as with multiple Disk game programs.