Memory FAQs

Q:What is Cache Memory? A: Cache Memory is a special high-speed memory designed to accelerate processing of memory instructions by the CPU. The CPU can access instructions and data located in cache memory much faster than instructions and data in main memory. For example, on a typical 100-megahertz system board, it takes the CPU as much as 180 nanoseconds to obtain information from main memory, compared to just 45 nanoseconds from cache memory. Therefore, the more instructions and data the CPU canaccess directly from cache memory the faster the computer can run.  Types of cache memory include primary cache (also known as Level 1 [L1] cache) and secondary cache (also known as Level 2 [L2] cache). Cache can also be referred to as internal or external. Internal cache is built into the computer’s CPU, and external cache is located outside the CPU

Q:What is DDR? A: Short for Dial-on-Demand Routing. DDR is a routing technique developed by Cisco that allows a user to utilize existing telephone lines, or public circuit-switched networks, to form a WAN instead of lines that are dedicated specifically to the WAN. DDR is typically implemented by users that do not need permanent, continuous links between sites on the WAN because the volume of traffic over the WAN is low and the transmissions are periodic as opposed to continuous. The connection only becomes active when data is sent to the remote site. When no data has been sent over the link for a specified amount of time, the link is disconnected.
Using DDR, a connection between sites is only established when a specific type of traffic initiates the call or when you a backup link is needed for redundancy or load sharing.

DDR is used in order to save on the costs of a dedicated WAN line for organizations that do not need permanent continuous connection and as a back-up by organizations that use the dedicated line for critical applications.

Q:What is DDR-SDRAM? A: Short for Double Data Rate-Synchronous DRAM, a type of SDRAM that supports data transfers on both edges of each clock cycle (the rising and falling edges), effectively doubling the memory chip’s data throughput. DDR-SDRAM also consumes less power, which makes it well-suited to notebook computers. DDR-SDRAM is also called SDRAM II.

Q:What SDRAM? A: Short for Synchronous DRAM, a type of DRAM that can run at much higher clock speeds than conventional memory. SDRAM actually synchronizes itself with the CPU’s bus and is capable of running at 133 MHz, about three times faster than conventional FPM RAM, and about twice as fast EDO DRAM and BEDO DRAM. SDRAM is replacing EDO DRAM in many newer computers.