IBM DBCA-204860 Hard Drive Specifications - Page 171
Write DMA, CAh/CBh
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12.34 Write DMA (CAh/CBh) Command Block Output Registers Register 76543210 Data Feature Sector Count V V V V V V V V Sector Number V V V V V V V V Cylinder Low V V V V V V V V Cylinder High V V V V V V V V Device/Head 1L1DHHHH Command 1100101R Command Block Input Registers Register 76543210 Data Error ...See Below... Sector Count V V V V V V V V Sector Number V V V V V V V V Cylinder Low V V V V V V V V Cylinder High V V V V V V V V Device/Head HHHH Status ...See Below... Error Register 76543210 CRC UNC 0 IDN 0 ABT T0N AMN V00V0V00 Status Register 76543210 BSY RDY DF DSC DRQ COR IDX ERR 0VVV 0 V Figure 109. Write DMA Command (CAh/CBh) The Write DMA command transfers one or more sectors of data from the host to the device, then the data is written to the disk media. The sectors of data are transferred through the Data Register 16 bits at a time. The host initializes a slave-DMA channel prior to issuing the command. Data transfers are qualified by DMARQ and are performed by the slave-DMA channel. The device issues only one interrupt per command to indicate that data transfer has terminated and status is available. If an uncorrectable error occurs, the write will be terminated at the failing sector. Output Parameters To The Device Sector Count The number of continuous sectors to be transferred. If zero is specified, then 256 sectors will be transferred. Sector Number The sector number of the first sector to be transferred. ( L = 0 ) In LBA mode, this register contains LBA bits 0 - 7. ( L = 1 ) Cylinder High/Low The cylinder number of the first sector to be transferred. ( L = 0 ) In LBA mode, this register contains LBA bits 8 - 15 (Low), 16 - 23 (High). ( L = 1 ) Command Descriptions 163