Tandy 1400LT - Step Pulse Timing; Write Data Timing (MFM

MOTOR ON
L
DIRECTION
WRITE DATA
- -
Ius min - -
r-
-
-
6ms rnin
r
_.
ZP- I ps min
-
250- 2 100 ns
21ms rnin
0 I
-
4
_-
5
Figure C-5. Step Pulse Timing
In consideration of a delay of a STEP pulse in a drive, the DIRECTION is latched at the trailing edge of the STEP
pulse.
Write Data
This line provides data to be written on the disk.
Each transition from “High” to “Low” changes the polarity of the R/W Head Current and causes a data bit to be
written on the disk.
Figure C-6 illustrates the Write Data timing in MFM recording.
Figure C-6. Write Data Timing (MFM)
When the power turned on or when the source voltage is suddenly dropped lower than 3.5V and returned to the
normal voltage, the write data signal is invalid for
10 msec after the source voltage returns to a normal level.
c-9