Re: Write Signal on Disk II Question

Mike,

I'm not sure if I entirely understand your question, but I'll give it a
try. When reading the disk, the controller derives it's timing from the
changing state of the fields. If you wrote eight ones and simply left the
field in a constant state, the controller would have a hard time
determining where one bit ended and another one started and the timing
would most likely be hopelessly out of whack after a just a few bits. This
is why there are requirements in each code word for limiting adjacent
zeros (which do not change the field) and manditory ones (which do change
the field).

Okay...I am talking about Write Sequence, but not Read Sequence. You
can write more than 3 ZERO bits to the disk without any problem. The Read
Sequence is not able to read more than 3 zero bits reliably. I am trying to
ask for the answers to my questions. My question -- Eight ONE bits is stored
in the data register and one bit is shifted out 8 times. The Write Signal
toggles from low to high or high to low each bit. It looks like four
present field reversals and four absence field reversals. Please explain
more in details how 8 ONE bits are stored between field reversals. Please
note that I talk about field reversals and Write Signal in Write Sequence.

Bryan Parkoff


.

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