FM/MFM data separators (was: WD 1793 FDCs for sale)

[Allison]

>
>Subject: FM/MFM data separators (was: WD 1793 FDCs for sale)
>   From: Philip Pemberton <philpem at dsl.pipex.com>
>   Date: Tue, 23 Aug 2005 08:16:24 +0100
>     To: cctalk at classiccmp.org
>
>In message <0ILN001WBHXEEOX0 at vms040.mailsrvcs.net>
>          Allison <ajp166 at bellatlantic.net> wrote:
>
>> If I can ever scan it there is a design I have (NEC apnote) for a
>> data seperator for FM/MFM that works for any rate and media.  Uses
>> a prom and a latch (yes a state machine) to do synthetic PLL. Analog 
>> PLLs were causing people too much pain and oneshots perform poorly.
>
>I would love a copy of that appnote - either scanned or photocopied is good
>(if photocopied, I'll scan it and put it online myself). I've seen another
>design that uses a state machine, but couldn't find any info on what it could
>handle or how it worked. It's on
><http://www.simandl.cz/stranky/zxs/zxs_a.htm> if anyone's interested.

That site has a copy of the circuit and the prom contents.  It can handle
all modes and rates.


>I'd really like to get my hands on any of the Rockwell/MOS/Synertek
>6502-series appnotes, or anything on the uPD765 or R6765. Also, has anyone
>got any data on the Fairchild 96LS488?

I'd like a scanner.

>> Lacking that if you can find SMC9229 or '39 part that does a lot 
>> of the work for you.
>
>*checks Google
>Obsolete and unobtainium. :(
>The datasheet is probably on Bitsavers, but I doubt it's got any real info on
>how the chip works internally. Certainly not enough to reimplement it from
>off-the-shelf parts.

It was never documeted on the fine detail.  As to unobtainium, I've managed
to find a few over time on XT and early at class FDC boards.  Likely there is
some NOS available somewhere.


Allison