Re: WD1000 Host Interface

[Eric Smith <eric-no-spam-for-me@brouhaha.com>]

"Eric" <lonewolf@hotmail.com> writes:
> Recently I picked up an old "WD1000 Host Interface" card (written on the
> card). It looks like a SCSI host adaptor with a 50pin connector.
> 
> Can anyone tell me what exact is this card? Where can I get more info or
> software for the card? I hope this is an Apple II card. I paid $1 for it.

Not SCSI, or even SASI.  It connects to a WD1000, 1001, or 1002 hard
disk controller.  The interface is fairly similar to IDE, since IDE traces
its lineage back to this family of controllers.

Many microcomputer companies (other than Apple) sold hard drive systems
in the early 1980s based on the WD controller boards, because back then
designing an HDC was a major endeavor.  Single-chip HDCs (e.g., WD1010,
NEC uPD7261) didn't appear until a few years later, and still required
an external data separator, which was a fairly finicky PLL circuit.