||A logic low on this input selects the chip and enable
Host communication with the device.
||A logic high on this input controls the placement of data
on the D0-D7 lines from a selected register, while a logic
low causes a write operation to a seleeted register.
||These two inputs select a register to Read/Write data:
CS A1 A0 R/W=1 R/W=0
0 0 0 Status Reg Command Reg
0 0 1 Track Reg Track Reg
0 1 0 Sector Reg Sector Reg
0 1 1 Data Reg Data Reg
||DATA ACCESS LINES 0 THRU 7
||Eight bit bidirectional bus used for transfer of data,
control, or status. This bus is enabled by CS and R/W.
Each line will drive one TTL load.
||A logic low pulse on this line resets the device
and initializes the status register (internal pull-up).
||+5V ± 5% power supply input.
||The STEP output contains a pulse for each step of the
drive's R/W head. The WD 1770 and WD1772 offer different
||The DIRECTION output is high when stepping in
towards the center of the diskette, and low when stepping out.
||This input requires a free-running 50% duty cycle clock
(for internal timing) at 8MHz ± 1%.
||This active low input is the raw data line containing
both clock and data pulses from the drive.
||Active high output used to enable the spindle motor prior
to read, write or stepping operations.
||This output is made valid prior to writing on the diskette.
||FM or MFM clock and data pulses are placed
on this line to be written on the diskette.
||This active low input informs the WD1770 that the drive's
R/W heads are positioned over Track Zero (internal pull-up).
||This active low input informs the WD1770 when the physical Index
Hole has been encountered on the diskette (internal pull-up).
||This input is sampled whenever a
Write Command is received. A logic low on this line will prevent any Write Command from executing
||DOUBLE DENSITY ENABLE
||This input pin selects either single (FM) or double
(MFM) density. When DDEN = 0, double density is selected
||This active high output indicates that the data register
is full (on a READ) or empty (on a Write operation).
||This active high output is set at the completion of any
command or reset or read of the status register.