Dma Controller

Some articles on dma controller, dma:

Direct Memory Access - Principle
... A DMA controller can generate addresses and initiate memory read or write cycles ... operation, the host processor initializes the DMA controller with a count of the number of words to transfer, and the memory address to use ... The DMA controller then provides addresses and read/write control lines to the system memory ...
Direct Memory Access - Examples - ISA
... In the original IBM PC, there was only one Intel 8237 DMA controller capable of providing four DMA channels (numbered 0-3), as part of the so-called Industry Standard Architecture, or ISA ... These DMA channels performed 8-bit transfers and could only address the first megabyte of RAM ... With the IBM PC/AT, a second 8237 DMA controller was added (channels 5-7 channel 4 is unusable), and the page register was rewired to address the full 16 MB memory ...
Cycle Stealing
... describe the "stealing" of a single CPU cycle, for example, to allow a DMA controller to perform a DMA operation ... This is opposed to block operation where a DMA controller would request a bus, hold it for a complete transaction (typically 16-32 bytes but could last much longer) before releasing to a CPU ... Cycle stealing generally occurs when the entire DMA transfer of data is finished, the DMA controller interrupts the CPU ...
Selected Tandy 1000 Models - Tandy 1000 SX/TX
... Tandy 1000 SX and TX were the first models in the Tandy 1000 line to have a built-in DMA controller. 1000 HD, 1000 EX and 1000 HX models, like the IBM PCjr, did not have a DMA controller, but could be upgraded with one ... The DMA controller chip was included on the PLUS-type memory expansion board for the EX and HX, and on regular ISA memory expansion cards sold by Tandy and other companies for the 1000, 1000A, and 1000HD ...