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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This happens without any CPU intervention. DMA transfers on any channel still cannot cross a 64 KiB boundary.

When the counting register reaches zero, the terminal count TC signal is untel to the datzsheet. 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.

It is used to repeat the last transfer. The transfer continues until end of process EOP either internal or external is activated which will trigger terminal count TC to the card.

The IBM PC and Inttel XT models machine types and have an CPU and an 8-bit system bus architecture; the latter interfaces directly to thebut the has a bit address bus, so four additional 4-bit address latches, one for each DMA channel, are added alongside the to augment the address counters. 823 the firstit is augmented with four address-extension registers.

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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. The is capable of DMA transfers at rates of up to 1. The is a four-channel device that can be expanded to include any number of DMA channel inputs.


The operates in four different modes, depending upon the number of bytes transferred per cycle and number of ICs used:.

Intel 8237

This technique is called “bounce buffer”. This means data can be transferred datasheeet one memory device to another memory device. 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.

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. For example, the P ISP integrated system peripheral controller has two DMA internal controllers programmed almost exactly like the Each channel is capable of addressing a full 64k-byte section of memory and can transfer up to 64k bytes datashert a single programming.

Views Read Edit View history. Although this device may not appear as a discrete component in modern personal computer systems, it does appear within system controller chip sets. This page was last edited on 21 Mayat Additionally, memory-to-memory intl DMA would require use of channel 4, conflicting with its use to cascade the itel handles the 8-bit DMA channels.

As a member of the Intel MCS device family, the is an 8-bit device with bit addressing.


By using this site, you agree to the Terms of Use and Privacy Policy. Auto-initialization may be programmed in xatasheet mode.

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. For every transfer, the counting register is decremented and address is incremented or decremented depending on programming.

In datasheeg initialize mode the address and count values are restored upon reception of an end of process EOP signal. Retrieved from ” https: 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.

At the end of transfer an datasheett initialize will occur configured to do so. 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, 4, In single mode only one byte is transferred per request.

Memory-to-memory transfer can be performed.

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.