A datasheet, A pdf, A data sheet, datasheet, data sheet, pdf, Intel, Multimode DMA Controller. Data Sheet for DMA Control Unit. REL iWave Systems Technologies Pvt. Ltd. Page 2 of (Confidential). DOCUMENT REVISION HISTORY. Revision. DATASHEET. The 82C37A is an enhanced version of the industry standard. A Direct Memory Access (DMA) controller, fabricated.

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The operates in four different modes, depending upon the number of bytes transferred per cycle and number of ICs used:. Memory-to-memory transfer can be performed. This page was last edited on 21 May datxsheet, at By using this site, you agree to the Terms of Use and Privacy Policy. In an AT-class PC, all eight of the address augmentation registers are 8 bits wide, so that full bit addresses—the size of the address bus—can be specified.

This technique is called “bounce buffer”. When the counting register reaches zero, the terminal count TC signal is sent to the card. From Wikipedia, the free encyclopedia. Like the firstit is augmented with four address-extension registers.

For every transfer, the counting register is decremented and address is incremented or decremented depending on programming. For example, the P ISP integrated system peripheral controller has two DMA internal controllers programmed almost exactly like the In general, it loses any overall speed benefit associated with DMA, but it may be necessary if a peripheral requires to be accessed by DMA due to either demanding timing requirements or hardware interface inflexibility.

  ASTM F1140 PDF

At the end of transfer datashwet auto initialize will occur configured to do so.

Intel – Wikipedia

So that it can address bit words, it is connected to the address bus in such a way that it counts even addresses 0, 2, datasjeet, DMA transfers on any channel still cannot cross a 64 KiB boundary.

This happens without any CPU intervention. Auto-initialization may be programmed in this mode. Consequently, a limitation on these machines is that the DMA controllers with their companion address “page” extension registers only can address 16 MiB of memory, according to the original design oriented around the CPU, which itself has this same addressing limitation.

Although this device may not appear as a discrete component in modern personal computer systems, it does appear within system controller chip sets.

As a member of the Intel MCS device family, the is an 8-bit device with intep addressing. Views Read Edit View history. Additionally, memory-to-memory bit DMA would require use of channel 4, conflicting with its use to cascade the datasheeh handles the 8-bit DMA channels. The transfer continues until end of process EOP either internal or external is activated which will trigger terminal count TC to the card.

Intel 8237

Because the memory-to-memory DMA mode operates by transferring a byte from the source memory location to an internal temporary 8-bit register in the and then from the temporary register to the destination memory location, this mode could not be used for bit memory-to-memory DMA, as the temporary register is not large enough.

The is a four-channel device that can be expanded to include any number of DMA channel inputs. It is used to repeat the last transfer.


This means data can be transferred from one memory device to another memory device. Each channel is capable of addressing a full 64k-byte section of memory and can transfer up to 64k inteel with a single programming. Retrieved from ” https: In single mode only one byte is transferred per request.

The channel 0 Current Address register is the source for the data transfer and channel 1 and the transfer terminates when Current Word Count register becomes 0.

The is capable of DMA transfers at rates of up to 1. The IBM PC and PC XT models machine types and have an CPU and an 8-bit system bus intell the latter interfaces directly to thebut the has a bit address bus, so four additional inhel address latches, one for each DMA channel, are added alongside datwsheet to augment the address counters.

However, because these external latches are separate from the address counters, they are never automatically incremented or decremented during DMA operations, making it impossible to perform a DMA operation across a 64 KiB address boundary. In auto initialize mode the address and count values are restored upon reception of an end of process EOP signal.

For this mode of transfer, the width of the data bus is essentially immaterial to the as long as it is connected to a data bus at least 8 bits wide, for programming the registers.