
W83877AF
Publication Release Date: Dec. 1996
Preliminary Version 0.52
- 18 -
1.5 IDE and FDC Interface, continued
SYMBOL
PIN
82
I/O
OD
24
FUNCTION
STEP
Step output pulses. This active low open drain output produces a
pulse to move the head to another track.
This schmitt input from the disk drive is active low when the
head is positioned over the beginning of a track marked by an
index hole. This input pin is pulled up internally by an
approximately 1K ohm resistor. The resistor can be disabled by
bit 4 of CR6 (FIPURDWN).
Track 0. This schmitt input from the disk drive is active low when
the head is positioned over the outermost track. This input pin is
pulled up internally by an approximately 1K ohm resistor. The
resistor can be disabled by bit 4 of CR6 (FIPURDWN).
INDEX
81
IN
cs
TRAK0
78
IN
cs
WP
77
IN
cs
Write protected. This active low schmitt input from the disk drive
indicates that the diskette is write-protected. This input pin is
pulled up internally by an approximately 1K ohm resistor. The
resistor can be disabled by bit 4 of CR6 (FIPURDWN).
RDATA
74
IN
cs
The read data input signal from the FDD. This input pin is pulled
up internally by an approximately 1K ohm resistor. The resistor
can be disabled by bit 4 of CR6 (FIPURDWN).
DSKCHG
76
IN
cs
Diskette change. This signal is active low at power on and
whenever the diskette is removed. This input pin is pulled up
internally by an approximately 1K ohm resistor. The resistor can
be disabled by bit 4 of CR6 (FIPURDWN).
MOA
79
OD
24
Motor A On. When set to 0, this pin enables disk drive 0. This is
an open drain output.
MOB
80
OD
24
Motor B On. When set to 0, this pin enables disk drive 1. This is
an open drain output.
DSA
83
OD
24
Drive Select A. When set to 0, this pin enables disk drive A. This
is an open drain output.
DSB
84
OD
24
Drive Select B. When set to 0, this pin enables disk drive B. This
is an open drain output.
V
DD
15,
56
+5 Volt power supply for the digital circuitry
GND
25,
40,
65,
90
Ground