Re: Write Signal on Disk II Question

["Bryan Parkoff" <nospam@nospam.com>]

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