W83877TF/W83877TG
-14 -
FDC Interface, continued
SYMBOL PIN I/O FUNCTION
INDEX
81 IN
cs
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).
TRAK0
78 IN
cs
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).
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.
VDD 15, 56 +5 power supply for the digital circuitry.
GND 25, 40 65, 90 Ground.
