Understanding DRAM in Modern Computing

• A computer's CPU works with data only after it has been moved to DRAM, also known as working memory or main memory.
• DRAM temporarily stores data in 2D arrays of capacitor memory cells, while SSDs permanently store data in 3D arrays of memory cells.
• DRAM access time is 17 nanoseconds, while SSD access time is 50 microseconds, a difference of 3000 times.
• DRAM has a 2D array structure and temporarily stores one bit per memory cell, while an SSD holds more data.
• DRAM requires continuous power to store data, while an SSD does not.
• By copying data from the SSD to DRAM and prefetching, a computer can store and access large amounts of data quickly.
• DRAM is used in various electronic devices such as GPUs, smartphones, and laptops with different optimizations.
• The CPU manages the flow of data between the SSD and DRAM using separate sections and memory channels.
• DDR5 memory channels are divided into two parts, each transferring 32 bits at a time using 32 data wires and 21 address and control signal wires.
• DRAM microchips consist of an interconnection matrix, a die, and an exterior packaging.
• A DRAM die is organized into bank groups, each containing 4 banks and 8 bank groups in total.
• Each bank contains 65,536 memory cells, and the chip reads or writes 8 bits at a time.
• A 31-bit address is used to access 17 billion memory cells, with the first 3 bits selecting the bank group, 2 bits selecting the bank, and the remaining bits determining the row and column address.
• DRAM chips are manufactured on 300-millimeter silicon wafers in a semiconductor fabrication plant using various tools and processes.
• Micron manufactures around a quarter of the world's DRAM, including Nvidia's and AMD's VRAM, and also produces its own product line of DRAM and SSDs under the brand Crucial.
• A Crucial NVMe solid-state drive can improve loading times and ensure smooth gameplay by eliminating the main speed bottleneck.- DRAM memory cells are organized into massive arrays with capacitors and transistors.
• The capacitor, shaped like a deep trench in silicon, stores one bit of data as electrical charges or electrons.
• The transistor, attached to the capacitor, accesses and reads or writes data by connecting the capacitor to the bitline.
• When the wordline is active, all capacitors in the same row are connected to their bitlines, activating the corresponding memory cells.
• Each bank in DRAM contains 65,536 rows and 8,192 columns, and a 31-bit address is used to access a group of 8 memory cells.
• Reading from a memory cell involves sending an address to the DRAM, precharging the bitlines, activating a single row, and detecting the change in voltage on the bitline using a sense amplifier.
• Writing to a memory cell is similar to reading, but involves overwriting the previous voltage with the new data using stronger write drivers.
• Charges in DRAM capacitors leak over time, so the memory cells need to be refreshed every 64 milliseconds to prevent data loss.
• DRAM has 32 banks to increase the likelihood of a row hit and reduce the average time it takes for the CPU to access data.
• A burst buffer is an additional storage location for temporarily loading and caching data, allowing for faster access to multiple sets of data.
• DRAM arrays are broken up into smaller subarrays to reduce the distance and wire usage between capacitors and sense amplifiers.
• A cross-coupled inverter inside the sense amplifier maintains a differential pair of active and passive bitlines, ensuring that they are always opposite one another and don't interfere with stored data.
• The design of a differential pair of bitlines has three benefits: easier precharge, faster access times, and reduced capacitive load.- DRAM (Dynamic Random Access Memory) uses coupled inverters and a transistor to create two oppositely charged electric wires, reducing electric fields and increasing sense amplifier's ability to amplify one bitline to 1 volt and the other to 0 volts.
• This setup provides benefits such as noise immunity and a reduction in parasitic capacitance of the bitline.
• DRAM's timing of addresses, command signals, and data are significant topics, with related acronyms DDR (double data rate) and SDRAM (Synchronous DRAM) often discussed.
• DRAM video omitted these topics due to additional 15 minutes required for proper exploration.
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• DRAM is crucial technology in modern computing.
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This quiz delves into the inner workings of DRAM (Dynamic Random Access Memory) and its role in modern computing technology. It covers topics such as the structure, functionality, access time, power requirements, manufacturing, and applications of DRAM, along with comparisons to SSDs. Whether you're a tech enthusiast or a student of computer hardware, this quiz offers valuable insights into the fundamental technology behind computer memory.