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PC87366 数据表(PDF) 25 Page - National Semiconductor (TI) |
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PC87366 数据表(HTML) 25 Page - National Semiconductor (TI) |
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25 / 240 page  1.0 Signal/Pin Connection and Description (Continued) 25 www.national.com 1.4.5 Floppy Disk Controller (FDC) Signal Pin(s) I/O Buffer Type Power Well Description DENSEL 75 O O2/12 VDD Density Select. Indicates that a high FDC density data rate (500 Kbps or 1 Mbps) or a low density data rate (250 or 300 Kbps) is selected. DENSEL polarity is controlled by bit 5 of the FDC Configuration Register. DIR 68 O OD12,O2/12 VDD Direction. Determines the direction of the Floppy Disk Drive (FDD) head movement (active = step in, inactive = step out) during a seek operation. During reads or writes, DIR is inactive. DR0 70 O OD12,O2/12 VDD Drive Select 0. Decoded drive select output signal. DR0 is controlled by bit 0 of the Digital Output Register (DOR). DR1 71 O OD12,O2/12 VDD Drive Select 1. Decoded drive select output signal. DR0 is controlled by bit 1 of the Digital Output Register (DOR). DRATE0 74 O O3/6 VDD Data Rate 0. Reflects the value of bit 0 of the Configuration Control Register (CCR) or the Data Rate Select Register (DSR), whichever was written to last. Output from the pin is push-pull buffered. DSKCHG 60 I INT VDD Disk Change. Indicates if the drive door has been opened. The state of this pin is stored in the Digital Input Register (DIR). This pin can also be configured as the RGATE data separator diagnostic input signal via the MODE command. HDSEL 61 O OD12,O2/12 VDD Head Select. Determines which side of the FDD is accessed. Active low selects side 1, inactive selects side 0. INDEX 73 I INT VDD Index. Indicates the beginning of an FDD track. MTR0 72 O OD12,O2/12 VDD Motor Select 0. Active low, motor enable line for drives 0, controlled by bits D7-4 of the Digital Output Register (DOR). MTR1 69 O OD12,O2/12 VDD Motor Select 1. Active low, motor enable lines for drives 1, controlled by bits D7-4 of the Digital Output Register (DOR). RDATA62 I INT VDD Read Data. Raw serial input data stream read from the FDD. STEP 67 O OD12,O2/12 VDD Step. Issues pulses to the disk drive at a software programmable rate to move the head during a seek operation. TRK0 64 I INT VDD Track 0. Indicates to the controller that the head of the selected floppy disk drive is at track 0. WDATA66 O OD12,O2/12 VDD Write Data. Carries out the pre-compensated serial data that is written to the floppy disk drive. Pre-compensation is software selectable. WGATE 65 O OD12,O2/12 VDD Write Gate. Enables the write circuitry of the selected disk drive. WGATE is designed to prevent glitches during power up and power down. This prevents writing to the disk when power is cycled. WP 63 I INT VDD Write Protected. Indicates that the disk in the selected drive is write protected. A software programmable configuration bit (FDC configuration at Index F0h, Logical Device 0) can force an active write-protect indication to the FDC, regardless of the status of this pin. |
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