ST-506 hard drive emulation

[Scott Stevens]

On Tue, 26 Jul 2005 21:02:47 +0100 (BST)
ard at p850ug1.demon.co.uk (Tony Duell) wrote:

> > > Correct. Don't uou have at least one ST506/ST412-interfaced drive
> > > schematic?
> > 
> > Nope, unfortunately not :-( I've got various manuals for bridge
> > boards, which of course have the connector pin-outs in (and give
> > some of the theory), but nothing for a complete hard drive (I
> > suppose I'mactually surprised such schematics ever escaped the drive
> > manufactuers to be honest, as presumably ST506/412 units were never
> > supposed to be field servicable?)
> 
> THe HDAs were not field-repairable, but the PCBs certainly were/are. 
> 
> The IBM PC series TechResf contain schematics of some such drives
> (which ones depends on exactly which version fo the TechRef amd which
> updates you have). I've traced out a couple more. In general these
> drives are not particularly complicated, although there may well be
> ASICs for things like head switching, motor control, etc.
> 

At one point I grabbed a copy, I don't know where I got it, but think it
was from a Tandy 4000 Technical Reference Manual, of a Technical
Reference the ST-225 (the old classic 20 meg ST-506 drive that EVERYBODY
had back then.)  I believe it has schematic diagrams.  The bad thing is
that it's in a file cabinet behind a BIG pile of gear right now.