What is random-access memory (RAM) and how does it work?
Random-access memory is a form of electronic computer memory that can be read and written in any order, with nearly identical access time regardless of where the data is stored on the chip. Modern RAM takes the form of integrated circuit chips using MOS memory cells. The two main types are SRAM, which uses a flip-flop circuit requiring six transistors per bit, and DRAM, which uses a single transistor-capacitor pair per bit and must be refreshed every few milliseconds to prevent data loss.
Who invented DRAM and when was it patented?
Robert Dennard invented modern DRAM architecture at IBM in 1966 after discovering that a MOS transistor could control whether a charge was written to a MOS capacitor. He filed a patent under IBM in 1967 for the single-transistor DRAM memory cell. The first commercial DRAM chip, the Intel 1103 with a capacity of 1 kilobit, was released in October 1970.
What was the first practical form of random-access memory?
The first practical form of random-access memory was the Williams tube, which stored data as electrically charged spots on the face of a cathode-ray tube. Developed at the University of Manchester in England, it provided the memory on which the first electronically stored program ran, in the Manchester Baby computer on the 21st of June, 1948. Its capacity was a few hundred to around a thousand bits.
What is the difference between SRAM and DRAM?
SRAM stores each bit using a flip-flop circuit that typically requires six MOSFETs, making it faster and lower in static power consumption but more expensive to produce and less dense. DRAM stores each bit using a single transistor-capacitor pair, achieving greater density and lower cost but requiring periodic refresh cycles every few milliseconds. SRAM is used primarily as CPU cache memory, while DRAM is the predominant form of main memory in modern computers.
What is the memory wall in computing?
The memory wall is the growing speed disparity between CPUs and main memory. From 1986 to 2000, CPU speed improved at roughly 55 percent per year while off-chip memory response time improved at only about 10 percent annually. An Intel document from 2005 identified transistor leakage, memory latency, the von Neumann bottleneck, and resistance-capacitance signal delays as compounding causes.
When did Samsung introduce synchronous DRAM and DDR SDRAM?
Samsung introduced synchronous DRAM with the KM48SL2000 chip in 1992, which had a capacity of 16 megabits. The first commercial double data rate SDRAM was also Samsung's, a 64-megabit DDR SDRAM released in June 1998. Samsung also released the first GDDR graphics memory chip, a 16-megabit device, in 1998.