Search results
Results from the WOW.Com Content Network
Direct memory access (DMA) is a feature of computer systems that allows certain hardware subsystems to access main system memory independently of the central processing unit (CPU). [ 1 ] Without DMA, when the CPU is using programmed input/output , it is typically fully occupied for the entire duration of the read or write operation, and is thus ...
A direct-access storage device (DASD) (pronounced / ˈ d æ z d iː /) is a secondary storage device in which "each physical record has a discrete location and a unique address". The term was coined by IBM to describe devices that allowed random access to data, the main examples being drum memory and hard disk drives . [ 1 ]
Since the channel normally has direct access to the main memory, it is also often referred to as a direct memory access (DMA) controller. In the most recent implementations, the channel program is initiated and the channel processor performs all required processing until either an ending condition or a program controlled interrupt (PCI). This ...
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 computing, remote direct memory access (RDMA) is a direct memory access from the memory of one computer into that of another without involving either one's operating system. This permits high-throughput, low- latency networking, which is especially useful in massively parallel computer clusters .
A DEC Core Memory Unibus card (16K × 18) The Unibus was the earliest of several computer bus and backplane designs used with PDP-11 and early VAX systems manufactured by the Digital Equipment Corporation (DEC) of Maynard, Massachusetts. The Unibus was developed around 1969 by Gordon Bell and student Harold McFarland while at Carnegie Mellon ...
Additional memory addressing capabilities are present as required to access available resources: Models with >256 bytes of data address space (≥256 bytes of RAM) have a 16-bit stack pointer, with the high half in the SPH register. Models with >8 KiB of ROM add the 2-word (22-bit) JUMP and CALL instructions.
Due to the cycle timing, there were periods of the internal clock where the memory bus was guaranteed to be free. This allowed the computer designer to interleave access to memory between the CPU and an external device, say a direct memory access controller, or more commonly, a graphics chip. By running both chips at 1 MHz and stepping them one ...