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.
|Published (Last):||24 January 2015|
|PDF File Size:||11.69 Mb|
|ePub File Size:||15.19 Mb|
|Price:||Free* [*Free Regsitration Required]|
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 datasheey or hardware interface inflexibility.
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 datashet limitation. 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.
DMA transfers on any channel still cannot cross a 64 KiB boundary. 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, Memory-to-memory transfer can be performed.
In single mode only one byte is transferred per request. For every transfer, darasheet counting register is decremented and address is incremented or decremented depending on programming. Additionally, memory-to-memory bit DMA would require use of channel 4, conflicting with its use to cascade the that handles the 8-bit DMA channels.
The IBM PC and PC 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. 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.
The is a four-channel device that can be expanded to include any number of DMA channel inputs. Although this device may not appear as a discrete component in modern personal computer systems, it does appear within system controller chip datasheey.
The operates in four different modes, depending upon the number of bytes transferred per cycle and number of ICs used:. It is inteo to repeat the last transfer.
This technique is called “bounce buffer”. Each channel is capable of addressing a full 64k-byte section of memory and can transfer up to 64k bytes with a single programming. In auto initialize mode the address and count values are restored upon reception of an end of process EOP signal. Because the memory-to-memory DMA mode operates by transferring a byte eatasheet 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.
HTTP This page has been moved
Auto-initialization may be programmed in this mode. The is capable of DMA transfers at rates of up to 1.
When the counting register reaches zero, the terminal count TC signal is sent to the card. The transfer continues until end of process EOP either internal or external is activated which will trigger terminal count TC to the card.
At the end of transfer an auto initialize will occur configured to do so. This means data can be transferred from one memory device to another memory device. This happens without any Darasheet intervention.
Like the firstit is augmented with four address-extension registers. As a member of the Intel MCS device family, the is an 8-bit device with bit datashet.
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. Retrieved from ” https: This page was last edited on 21 Mayat