Re: ZipGS on eBay

["Michael J. Mahon" <mjmahon@aol.com>]

PZ wrote:
> Heres some info:  It'll boot GS/OS completely at that speed sometimes,
> but its far from stable.
>
> 18.75 = 2 out of 10 boots
> 18.00 = 8.5 out of 10 boots (yea, there's a big wall between 18 and
> 18.75)
> 17.00 = 10 out of 10 boots (occational weird crashes, reproducable)
> 16.00 = 10 our of 10 boots (occational weird crashes)
> 15.00 = 100% stable
>
> Most of the instability, but not all, at 16 and 17mhz has to do with
> floppy drive access.  I'm currently experimenting with additional caps
> on the 5v, 12v lines directly off of the floppy connector.

To be effective, bypass (decoupling) capacitors need to be
low-ESR (usually ceramic or monolithic 0.1uF) and need
to be installed *very* close to the current-spike generating
ICs--directly to the IC or socket power and ground pins is
not too close!

Six inches of wire or PC board trace is a fine inductor, which
has enough inductance to allow a local current spike to
create a surprisingly large local voltage spike.

Electrolytics for low-frequency ripple reduction are not of
any great value unless the power supply output filtering
capacitors are going south, except in the relatively rare
case of a *really* big current spike producer.

-michael