HP D315 manual Diskette Drive Interface Control Registers, Pri

Chapter 5 Input/Output Interfaces

Table 5–5. Diskette Drive Interface Control Registers
		Table 5-5.
		Diskette Drive Interface Control Registers
Pri.	Sec.
Addr.	Addr.	Register	R/W
3F0h	370h	Status Register A:	R
		<7> Interrupt pending
		<6> Reserved (always 1)
		<5> STEP pin status (active high)
		<4> TRK 0 status (active high)
		<3> HDSEL status (0 = side 0, 1 = side 1)
		<2> INDEX status (active high)
		<1> WR PRTK status (0 = disk is write protected)
		<0> Direction (0 = outward, 1 = inward)
3F1h	371h	Status Register B:	R
		<7,6> Reserved (always 1’s)
		<5> DOR bit 0 status
		<4> Write data toggle
		<3> Read data toggle
		<2> WGATE status (active high)
		<1,0> MTR 2, 1 ON- status (active high)
3F2h	372h	Digital Output Register (DOR):	R/W
		<7,6> Reserved
		<5,4> Motor 1, 0 enable (active high)
		<3> DMA enable (active high)
		<2> Reset (active low)
		<1,0> Drive select (00 = Drive 1, 01 = Drive 2, 10 = Reserved, 11 = Tape drive)
3F3h	373h	Tape Drive Register (available for compatibility)	R/W
3F4h	374h	Main Status Register (MSR):	R
		<7> Request for master (host can transfer data) (active high)
		<6> Transfer direction (0 – write, 1 = read)
		<5> non-DMA execution (active high)
		<4> Command busy (active high)
		<3,2> Reserved
		<1,0> Drive 1, 2 busy (active high)
		Data Rate Select Register (DRSR):	W
		<7> Software reset (active high)
		<6> Low power mode enable (active high)
		<5> Reserved (0)
		<4..2> Precompensation select (default = 000)
		<1,0> Data rate select (00 = 500 Kb/s, 01 = 300 Kb/s, 10 = 250 Kb/s, 11 = 2/1
		Mb/s)
3F5h	375h	Data Register:	R/W
		<7..0> Data
3F6h	376h	Reserved	--
3F7h	377h	Digital Input Register (DIR):	R
		<7> DSK CHG status (records opposite value of pin)
		<6..0> Reserved (0’s)
		Configuration Control Register (CCR):	W
		<7..2> Reserved

<1,0> Data rate select (00 = 500 Kb/s, 01 = 300 Kb/s, 10 = 250 Kb/s, 11 = 2/1 Mb/s)

NOTE: The most recently written data rate value to either DRSR or CCR will be in effect.

5-6Compaq D315 and hp d325 Personal Computers Featuring the AMD Athlon XP Processor

Second Edition – April 2003