Write Gate (Wgt); Write Data (Wdt); Low Write Current (Lwc); Wgt Timing - NEC FD1165 Maintenance Manual

3.3.6 Write Gat:e (WGT)
This signal selects the read or write operation. If the
signal is Low, data is written to the disk. If the signal
is High, da ta is read from the dis k. Dur ing the Wr ite
operation, data is erased between adjacent tracks on the
flexible disk for 560
~s
after WGT goes High. During this
560
~s,
the Head Load signal cannot· be disabled, the Side
Select signal cannot be changed, and the Step opera tion
cannot be enabled. These signals can be changed only when
the WGT and Erase signals are both High. Figure 3-4 is the
WGT timing chart.
WGT \
I
~.
-.1
ERASE SIGNAL \
I
NOTE: THE HEAD LOAD SIGNAL CANNOT BE TURNED OFF, THE SIDE SELECT
SIGNAL CANNOT BE CHANGED. AND THE STEP OPERATION CANNOT
BE ENABLED DURING THIS INTERVAL.
Figure 3-4 WGT Timing
3.3.7 Write Data (WDT)
The signals- on this line contain the data that is written
on the flexible disk. The da ta is in Frequency Modula ted
(FM) or in Modified Frequency- Modulated (MFM) format (see
Figure 3-5).
3.3.8 Low Write Current (LWC)
This signal controls the write current amplitude to compen-
sa te for the di fference in dens i ty between the inner and
outer tracks of the flexible disk. The LWC signal is High
for external tracks
(00
to
42)
and Low for internal tracks
(43 to 76).
3-5