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FDC37C78-HT Datasheet(PDF) 25 Page - Microchip Technology |
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FDC37C78-HT Datasheet(HTML) 25 Page - Microchip Technology |
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25 / 82 page  25 Table 17 - Status Register 3 BIT NO. SYMBOL NAME DESCRIPTION 7 Unused. This bit is always "0". 6 WP Write Protected Indicates the status of the WP pin. 5 Unused. This bit is always "1". 4 T0 Track 0 Indicates the status of the TRK0 pin. 3 Unused. This bit is always "1". 2 HD Head Address Indicates the status of the HDSEL pin. 1,0 DS1,0 Drive Select Indicates the status of the DS1, DS0 pins. RESET There are three sources of system reset on the FDC: the RESET pin of the FDC37C78, a reset generated via a bit in the DOR, and a reset generated via a bit in the DSR. At power on, a Power On Reset initializes the FDC. All resets take the FDC out of the power down state. All operations are terminated upon a RESET, and the FDC enters an idle state. A reset while a disk write is in progress will corrupt the data and CRC. On exiting the reset state, various internal registers are cleared, including the Configure command information, and the FDC waits for a new command. Drive polling will start unless disabled by a new Configure command. RESET Pin (Hardware Reset) The RESET pin is a global reset and clears all registers except those programmed by the Specify command. The DOR reset bit is enabled and must be cleared by the host to exit the reset state. DOR Reset vs. DSR Reset (Software Reset) These two resets are functionally the same. Both will reset the FDC core, which affects drive status information and the FIFO circuits. The DSR reset clears itself automatically while the DOR reset requires the host to manually clear it. DOR reset has precedence over the DSR reset. The DOR reset is set automatically upon a pin reset. The user must manually clear this reset bit in the DOR to exit the reset state. MODE OF OPERATION PC/AT mode - (IDENT high, MFM a "don't care") The PC/AT register set is enabled, the DMA enable bit of the DOR becomes valid (IRQ and DRQ can be hi Z), and TC and DENSEL become active high signals. |
Similar Part No. - FDC37C78-HT |
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Similar Description - FDC37C78-HT |
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