82077AA Datasheet, PDF (6/62 Pages) Intel Corporation – CHMOS SINGLE-CHIP FLOPPY DISK CONTROLLER

82077AA
Table 1 82077AA Pin Description (Continued)
Symbol Pin I O
Description
DISK CONTROL (All outputs have 40 mA drive capability) (Continued)
DENSEL 49 O DENSITY SELECT Indicates whether a low (250 300 Kbps) or high (500 Kbps 1
Mbps) data rate has been selected
DSKCHG 31 I DISK CHANGE This input is reflected in the Digital Input Register
DRV2
30 I DRIVE2 This indicates whether a second drive is installed and is reflected in
Status Register A
TRK0
2
I TRACK0 Control line that indicates that the head is on track 0
WP
1
I WRITE PROTECT Indicates whether the disk drive is write protected
INDX
26 I INDEX Indicates the beginning of the track
PLL SECTION
RDDATA 41
I READ DATA Serial data from the disk INVERT also affects the polarity of this
signal
HIFIL
38 I O HIGH FILTER Analog reference signal for internal data separator compensation
This should be filtered by an external capacitor to LOFIL
LOFIL
37 I O LOW FILTER Low noise ground return for the reference filter capacitor
MFM
48 I O MFM At Hardware RESET aids in configuring the 82077AA Internal pull-up
allows a no connect if a ‘‘1’’ is required After reset this pin becomes an output
and indicates the current data encoding decoding mode (Note If the pin is held at
logic level ‘‘0’’ during hardware RESET it must be pulled to ‘‘1’’ after reset to
enable the output The pin can be released on the falling edge of hardware
RESET to enable the output) MFM is active high (MFM)
DRATE0 28 O DATARATE0–1 Reflects the contents of bits 0 1 of the Data Rate Register
DRATE1 29
(Drive capability of ^a6 0 mA 0 4V and ^b4 0 mA 2 4V)
PLL0
39 I
MISCELLANEOUS
PLL0 This input optimizes the data separator for either floppy disks or tape
drives A ‘‘1’’ (or V_CC) selects the floppy mode a ‘‘0’’ (or GND) selects tape mode
VCC
18
40
60
68
Voltage ^a5V
GND
9
12
16
21
36
50
54
59
65
Ground
AVCC
46
Analog Supply
AVSS
45
Analog Ground
NC
42
No Connection These pins MUST be left unconnected
43
44
47
6