Woz and his 6 chips...

From: Richard Erlacher <richard_at_idcomm.com>
Date: Fri Jun 2 01:10:07 2000

Tony Duell listed them earlier today. There's a schematic in the patent,
IIRC. You can always look that up.

This particular design was a noteworthy engineering achievement because of
two factors. (1) Apple was able to replace the more costly logic board on
the drive with one of their own making, which saved a sizeable share of the
then still quite costly Shugart SA400 drives, and (2) this scheme which used
the local processor to do a lot of the work, including controlling the
stepping of the head, also provided DOUBLE DENSITY, which, if one used the
usual approach, i.e. a FDC LSI of one sort or another, would cost about $80
at the time, and that was just for the one IC. It required a fair amount of
support, a minimum of five or six additional IC's to provide head-load
timing, drive and receive the cable, extract clock from the incoming bit
stream, and perform the write precompensation. In the technology of the
time, it was not uncommon to see a dozen IC's involved. Some systems even
provided a DMAC to ensure they tansferred the data quickly enough.

In short is was better because it was way cheaper than the conventional
design. It worked rather well, too.

Dick

----- Original Message -----
From: Mike Cheponis <mac_at_Wireless.Com>
To: <classiccmp_at_classiccmp.org>
Sent: Thursday, June 01, 2000 10:14 PM
Subject: Re: Woz and his 6 chips...


> Ladies & Gents, now I -gotta- know: What were those 6 chips, and is there
a
> schematic somewhere?
>
> Also, why was this considered such an engineering achievement?
>
> Thanks! -mac
>
> On Thu, 1 Jun 2000, Will Jennings wrote:
>
> > FYI, Woz even talked about how he thought that his 6-chip design was one
of
> > his most brilliant ideas, in an interview in Byte in 1984...
> >
> > Will J
>
Received on Fri Jun 02 2000 - 01:10:07 BST