8272
DESCRIPTION
Hand-shaking signals are provided in the 8272 which make DMA operation easy to incorporate with the aid of an external DMA controller chip, such as the 8237. The FDC will operate in either DMA or Non-DMA mode. In the Non-DMA mode, the FDC generates interrupts to the processor for every transfer of a data byte between the CPU and 8272. In the DMA mode, the processor need only to load a mand into the FDC and all data transfers occur under control of the 8272 and DMA controller. There are 15 seperate mands which the 8272 will execute. Each of these mands require multiple 8-bit bytes to fully specify the operation which the processor wishes the FDC to perform. The following mands are available.
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Read Read Read Read
Data ID Deleted Data a Track
Scan Equal Scan High or Equal Scan Low or Equal Specify
Write Data Format a Track Write Deleted Data Seek Recalibrate (Restore to track 0) Sense Interrupt Status Sense Drive Status
FEATURES
Address mark detection curcuitry is...
