Apple Elite Series Computer Drive User Manual


 
ELITE SERIES USER MANUAL APPEN. A - DISK I/O
When a data field is written there is na guaran-
tee that the write will occur in the same spot
each time because the drive which is rewriting
the data field may not be the one which actually
INITed, or originally wrote it. Since the speed
of the drives can vary, it is perfectly possible
the write could start in mid-byte.
Normally, when writing a data field, five self-
sync bytes are written prior to writing the data
field itself. This is because the five bytes
help place the data field near its original
location. Secondly, the five self-sync bytes are
the minimum number required to guarantee
read—synchronization, as demonstrated in the
figure below:
Page A-21