Hitachi 7K400 Specifications - Page 158
Read DMA Ext 25h
UPC - 000053412935
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12.17 Read DMA Ext (25h) Table 103: Read DMA Ext Command (25h) Command Block Output Registers Register 7 6 5 4 3 2 1 0 Data Low Data High Feature Current Previous Sector Count Current Previous V V V V V V V V V V V V V V V V Sector Number Current Previous V V V V V V V V V V V V V V V V Cylinder Current Low Previous V V V V V V V V V V V V V V V V Cylinder Current High Previous V V V V V V V V V V V V V V V V Device/Head 1 1 1 0 - - - - Command 0 0 1 0 0 1 0 1 76 CRC UNC V Vs Error Register 54 3 2 1 0 0 IDN 0 ABT T0N AMN 0V 0 V 0 0 Command Block Input Registers Register 7 6 5 4 3 2 1 0 Data Low Data High Error see below Sector HOB=0 Count HOB=1 Sector HOB=0 Number HOB=1 Cylinder HOB=0 Low HOB=1 Cylinder HOB=0 High HOB=1 Device/Head Status V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V See below ... Status Register 7 654 3 2 1 0 BSY RDY DF DSC DRQ COR IDX ERR 0 V0V - 0 - V The Read DMA command reads one or more sectors of data from disk media, then transfers the data from the device to the host. The sectors are transferred through the Data Register 16 bits at a time. The host initializes a slave-DMA channel prior to issuing the command. The 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 read will be terminated at the failing sector. Output parameters to the device Sector Count Current The number of sectors to be transferred low order, bits (7:0). Sector Count Previous The number of sectors to be transferred high order, bits (15:8). If 0000h in the Sector Count register is specified, then 65,536 sectors will be transferred. Sector Number Current LBA (7:0) Sector Number Previous LBA (31:24) Cylinder Low Current LBA (15:8) Cylinder Low Previous LBA (39:32) Deskstar 7K400 Hard Disk Drive Specification 144