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The C programming language manages memory statically, automatically, or dynamically.Static-duration variables are allocated in main memory, usually along with the executable code of the program, and persist for the lifetime of the program; automatic-duration variables are allocated on the stack and come and go as functions are called and return.
The Word DMA (WDMA) interface is a method for transferring data between a computer (through an Advanced Technology Attachment (ATA) controller) and an ATA device; it was the fastest method until Ultra Direct Memory Access (UDMA) was implemented.
In computer science, message passing is a technique for invoking behavior (i.e., running a program) on a computer.The invoking program sends a message to a process (which may be an actor or object) and relies on that process and its supporting infrastructure to then select and run some appropriate code.
The DMA command is issued by specifying a pair of a local address and a remote address: for example when a SPE program issues a put DMA command, it specifies an address of its own local memory as the source and a virtual memory address (pointing to either the main memory or the local memory of another SPE) as the target, together with a block size.
Gather/scatter is a type of memory addressing that at once collects (gathers) from, or stores (scatters) data to, multiple, arbitrary memory indices. Examples of its use include sparse linear algebra operations, [1] sorting algorithms, fast Fourier transforms, [2] and some computational graph theory problems. [3]
Memory-mapped I/O is preferred in IA-32 and x86-64 based architectures because the instructions that perform port-based I/O are limited to one register: EAX, AX, and AL are the only registers that data can be moved into or out of, and either a byte-sized immediate value in the instruction or a value in register DX determines which port is the source or destination port of the transfer.
Zero-copy programming techniques can be used when exchanging data within a user space process (i.e. between two or more threads, etc.) and/or between two or more processes (see also producer–consumer problem) and/or when data has to be accessed / copied / moved inside kernel space or between a user space process and kernel space portions of operating systems (OS).
Intel 8237A-5, used on the original IBM PC motherboard Pinout. Intel 8237 is a direct memory access (DMA) controller, a part of the MCS 85 microprocessor family. It enables data transfer between memory and the I/O with reduced load on the system's main processor by providing the memory with control signals and memory address information during the DMA transfer.