w83877atd Winbond Electronics Corp America, w83877atd Datasheet - Page 19

• Manufacturer Part Number: w83877atd
• Description: Winbond I/o
• Manufacturer: Winbond Electronics Corp America

1.4 FDC interface, continued
MOA
MOB
DSA
DSB
DIR
V
GND
WD
INDEX
WE
RWC
HEAD
STEP
SYMBOL
DD
PIN
15,
25,
65,
81
79
80
82
83
84
85
86
87
88
89
56
40
90
OD
OD
OD
OD
OD
OD
OD
OD
OD
OD
IN
I/O
cs
24
24
24
24
24
24
24
24
24
24
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).
Motor A On. When set to 0, this pin enables disk drive 0. This is
an open drain output.
Motor B On. When set to 0, this pin enables disk drive 1. This is
an open drain output.
Step output pulses. This active low open drain output produces a
pulse to move the head to another track.
Drive Select A. When set to 0, this pin enables disk drive A. This
is an open drain output.
Drive Select B. When set to 0, this pin enables disk drive B. This
is an open drain output.
Write enable. An open drain output.
Write data. This logic low open drain writes precompensation
serial data to the selected FDD. An open drain output.
Reduced write current. This signal can be used on two-speed disk
drives to select the transfer rate. An open drain output.
Logic 0 = 250 Kb/s
Logic 1 = 500 Kb/s
When bit 5 of CR9 (EN3MODE) is set to high, the three-mode
FDD function is enabled, and the pin will have a different
definition. Refer to the EN3MODE bit in CR9.
Head select. This open drain output determines which disk drive
head is active.
Logic 1 = side 0
Logic 0 = side 1
Direction of the head step motor. An open drain output.
Logic 1 = outward motion
Logic 0 = inward motion
+5 power supply for the digital circuitry
Ground
- 15 -
FUNCTION
Publication Release Date: April 1998
W83877ATF
Version 0.51