Re: Iomega Zip drive MFM or GCR?

["Rick Balkins" <rickbalkins.nospam@nospam.gmail.com>]

I'd be damn, my guess prior was RLL but I left open for newer schemes that 
may exists in the 250 MBytes Zip disks versus the 100 MB.

Got a good point.

"Anssi Saari" <as@sci.fi> wrote in message 
vg33aeqp5bp.fsf@omppu.modeemi.cs.tut.fi">news:vg33aeqp5bp.fsf@omppu.modeemi.cs.tut.fi...
> "Rick Balkins" <rickbalkins.nospam@nospam.gmail.com> writes:
>
>> Another additional thing is PRML or extended PRML (EPRML).
>> The zip disk would resemble a hard drive more then a floppy disk in the
>> encoding scheme.
>
> We might guess RLL. I found a paper from Quantum
> (http://www.forensicswiki.org/images/c/c6/Maxtor_PRML_Read_Channels.pdf)
> where they say they first put PRML in their Empire drives in 1993.
> Maybe IBM did it already in 1992 when they came out with the first
> 3.5" 1 GB drive
> (http://www-03.ibm.com/ibm/history/exhibits/storage/storage_chrono20.html).
>
> The Empire models were apparently 540 MB - 2 GB in size. The 540 model
> had four heads so presumably 270 MB per platter, almost three times
> the capacity of Zip media which came out in 1994. So one might think
> Zips used old encoding since they weren't exactly top of the line in
> storage density back then.
>
> Well, it looks like Gibson Research confirms it, RLL was used, at
> http://www.grc.com/tip/codknowledge.htm which is about the click of
> death.
>