Tandy 1000 HX Technical Reference Manual page 383

3,4,5 Index Pulse
T2
Tl* : 197 ms min.
f
203 ms max.
T2 : 1.25 ms min., 1,45 ms max.
* When the disk motor rotation is at the stable state.
3.4.6 Disk Change
Tl : 0.5 us max. T2 : 1.6 us max.
*DISK IN, the disk-in sensor signal inside the drive, is
high when a disk is inserted in the drive.
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