A memory channel is the primary communication pathway between the CPU's memory controller and the RAM modules. This configuration uses a single channel with a 64-bit data bus width, allowing 8 bytes to be transferred simultaneously. Modern systems often use dual or quad-channel configurations for increased bandwidth.
🔍 Key Concept: The channel represents the physical and electrical connection that enables data transfer. A wider bus (more channels) means more data can move in parallel, dramatically increasing memory bandwidth.
Total Capacity
16.0 GB
Bus Width
64 bits
Transfer per Cycle
8 bytes
Connected DIMMs
4 modules
💾
MEMORY CHANNEL
16.0 GB
• 64-bit Data Bus
• 4 DIMM Slots
• DDR4 Interface
👆 Click to explore DIMMs
🔌 Channel Physical Layout & Cross-Section
TOP VIEW - Motherboard
SIGNAL LAYERS
DATA LINES [63:0] - 64 parallel traces
ADDRESS LINES [13:0] - Row/Column address
COMMAND LINES - RAS, CAS, WE signals
CLOCK - Differential clock signals
Channel Width:64 bits (8 bytes)
Max Transfer Rate:DDR4-2666: 21.3 GB/s
DIMM Slots:4 slots per channel
💾DIMM (Dual In-line Memory Module)
DIMMs are the physical circuit boards that hold memory chips. Each DIMM in this configuration contains 4 GB of memory organized into 2 ranks. The "dual in-line" refers to the pins on both sides of the module that provide separate electrical contacts. DIMMs plug into motherboard slots and can be easily upgraded or replaced.
🔍 Architecture: Each DIMM contains multiple memory chips arranged on a PCB. The memory controller can address each DIMM independently, and the dual-rank design allows for better density without requiring larger chips.
A rank is a set of memory chips that can be accessed simultaneously by the memory controller. Each rank represents a 64-bit wide data path (matching the channel width). Ranks on the same DIMM share the same data and address buses but have separate chip select signals, meaning only one rank on a DIMM can be active at a time.
🔍 Why Ranks Matter: Dual-rank DIMMs offer better performance than single-rank in many workloads because while one rank is being accessed, the other can be preparing for the next operation (rank interleaving). This overlapping reduces latency.
Capacity per Rank
2.0 GB
Chips per Rank
8 chips
Data Width
64 bits
Chip Capacity
2 Gbit each
2 Ranks per DIMM (Side-by-Side)
🔲
RANK 0 (Front)
2.0 GB
• 8 Memory Chips
• 256 MB per chip
• Primary Rank
• 64-bit data bus
👆 Click to see Chips
🔲
RANK 1 (Back)
2.0 GB
• 8 Memory Chips
• 256 MB per chip
• Secondary Rank
• 64-bit data bus
👆 Click to see Chips
8 chips working together (each contributes 8 bits to the 64-bit bus)
🔲Memory Chips (DRAM ICs)
Each memory chip is an integrated circuit (IC) containing the actual DRAM cells where data is stored. In this configuration, each chip has a capacity of 2 Gbit (256 MB) and contributes 8 bits to the 64-bit data bus. The chip is internally organized into 8 banks, allowing multiple memory operations to be pipelined for better performance.
🔍 Parallel Processing: When you read 64 bits from memory, all 8 chips work simultaneously—each chip provides 8 bits. This parallel architecture is why memory bandwidth scales with the number of chips in a rank.
Chip Capacity
256 MB
Density
2 Gbit
Banks per Chip
8 banks
Data Width
8 bits
8 Memory Chips in Rank
🟦
CHIP 0
256 MB
• Bits [7:0]
• 8 Banks
• 2 Gbit density
👆 Explore Banks
🟦
CHIP 1
256 MB
• Bits [15:8]
• 8 Banks
• 2 Gbit density
👆 Explore Banks
🟦
CHIP 2
256 MB
• Bits [23:16]
• 8 Banks
• 2 Gbit density
👆 Explore Banks
🟦
CHIP 3
256 MB
• Bits [31:24]
• 8 Banks
• 2 Gbit density
👆 Explore Banks
🟦
CHIP 4
256 MB
• Bits [39:32]
• 8 Banks
• 2 Gbit density
👆 Explore Banks
🟦
CHIP 5
256 MB
• Bits [47:40]
• 8 Banks
• 2 Gbit density
👆 Explore Banks
🟦
CHIP 6
256 MB
• Bits [55:48]
• 8 Banks
• 2 Gbit density
👆 Explore Banks
🟦
CHIP 7
256 MB
• Bits [63:56]
• 8 Banks
• 2 Gbit density
👆 Explore Banks
🗄️Memory Banks
Banks are independent subdivisions within a memory chip that can be accessed concurrently. Each bank contains 32 MB (256 Mbit) organized into rows and columns. Bank interleaving allows the memory controller to access different banks simultaneously, hiding the latency of row activation and improving overall throughput.
🔍 Parallelism Power: While one bank is performing a row activation, another can be reading data, and yet another can be precharging. This pipeline parallelism is crucial for maintaining high memory bandwidth in real-world applications.
Capacity per Bank
32 MB
Density
256 Mbit
Rows per Bank
16,384
Row Size
2 KB
8 Banks in Memory Chip
📚
BANK 0
32 MB
• 16,384 Rows
• 16,384 Columns
• 2 KB row buffer
👆 View Rows
📚
BANK 1
32 MB
• 16,384 Rows
• 16,384 Columns
• 2 KB row buffer
👆 View Rows
📚
BANK 2
32 MB
• 16,384 Rows
• 16,384 Columns
• 2 KB row buffer
👆 View Rows
📚
BANK 3
32 MB
• 16,384 Rows
• 16,384 Columns
• 2 KB row buffer
👆 View Rows
📚
BANK 4
32 MB
• 16,384 Rows
• 16,384 Columns
• 2 KB row buffer
👆 View Rows
📚
BANK 5
32 MB
• 16,384 Rows
• 16,384 Columns
• 2 KB row buffer
👆 View Rows
📚
BANK 6
32 MB
• 16,384 Rows
• 16,384 Columns
• 2 KB row buffer
👆 View Rows
📚
BANK 7
32 MB
• 16,384 Rows
• 16,384 Columns
• 2 KB row buffer
👆 View Rows
📏Memory Rows & Row Buffer
Each bank contains 16,384 rows (2^14), and each row is 16,384 bits (2 KB) wide. When a row is accessed, the entire row is read into the row buffer—a high-speed cache within the chip. Subsequent accesses to the same row (row hits) are very fast since the data is already in the buffer. Accessing a different row requires precharging the current row and activating the new one (row miss), which incurs significant latency.
🔍 Row Buffer Optimization: Memory access patterns that maximize row buffer hits dramatically improve performance. This is why memory locality is so important—accessing sequential addresses keeps you in the same row, avoiding expensive row activation penalties.
Total Rows
16,384
Row Address Bits
14 bits (2^14)
Row Size
2 KB
Columns per Row
16,384
Sample Rows in Bank (16,384 total rows)
ROW 0 → 16,384 bits (2 KB)
ROW 1 → 16,384 bits (2 KB)
ROW 2 → 16,384 bits (2 KB)
⋮ 16,378 more rows ⋮
ROW 16,383 → 16,384 bits (2 KB)
📐Memory Columns & Individual Cells
Each row contains 16,384 columns (2^14), where each column holds a single bit. A column address selects which bits from the active row buffer are read or written. The intersection of a row and column identifies a unique memory cell. Each DRAM cell consists of a tiny capacitor that stores a bit as electrical charge (charged = 1, discharged = 0) and a transistor that controls access to that capacitor.
🔍 The DRAM Cell: Each cell is incredibly small—measured in nanometers. The capacitor's charge leaks over time, which is why DRAM requires constant refreshing (every 64ms typically). This is the "Dynamic" in DRAM. The row/column architecture creates a dense 2D grid that maximizes storage density.
Columns per Row
16,384
Column Address Bits
14 bits (2^14)
Cell Size
1 bit
Burst Length
8 words
Column Grid Visualization (Simplified - showing 256 of 16,384 columns)
Each cell represents 1 bit of data • Hover to see cell interaction
Full grid: 16,384 × 16,384 = 268,435,456 bits = 32 MB per bank
💡 Burst Read Operation: When reading data, DDR4 performs burst transfers of 8 words (64 bytes total) from consecutive column addresses. This is why memory transfers happen in 64-byte chunks—it's the burst length multiplied by the 8-byte bus width.