Re: Question Soup (shielding, ColorSwitch, 16k ZIP)

[dempson@atlantis.actrix.gen.nz (David Empson)]

In article <4mm0dk$hvl@freenet-news.carleton.ca>,
Dan Markarian <ae196@FreeNet.Carleton.CA> wrote:
> 
> I would be very grateful if someone could shed some light on these q's...
>  
> (1) When I mount my IIgs in a tower case, do I attach the tower case
>     ground to the GS' cage?

The IIgs cage should be connected to earth, not to signal ground.

> (2) The GS is mounted on its side with the cards properly supported in
>     the tower, without the GS' original top cover.  Do I also need to
>     set up the metallic cage previously part of the the GS' top cover
>     above the expansion cards?

It would help to reduce RF interference if you can do this.

> (3) Does it make sense that a Zip/GS installed with 32 Kb of SRAM in
>     the first two banks (32Kbx8's) work in the 16Kb configuration?
>     It does work, but makes no sense to me.

Do you mean that it has 32KB in two banks and 8KB in the other two
banks?  If so, yes.  8KB and 32KB RAMs are pin-compatible: the only
differences on the 8KB RAM are an unused pin (corresponding to A14 on
the 32KB RAM) and an active-high chip select line (corresponding to
A13 on the 32KB RAM).  All that is happening is that the ZIP is only
making use of 8KB of each 32KB RAM.

> (4) Attaching my monitor via my PC Transporter ColorSwitch causes a
>     kind of slow flickering and a moving wavey 'pattern' to the GS'
>     image.  I tried placing the ColorSwitch as far away from the
>     motherboard and power supply with no visible difference.  What
>     could be causing this?

The ColorSwitch does introduce a little distortion and lowering of the
signal levels.  The extra cabling probably increases its sensitivity
to environmental noise.  I don't get flickering, though - you might
have a faulty ColorSwitch.

The wavy pattern you describe sounds like an interference pattern
(beating) with another monitor or power supply running at the same
scan frequency.
-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand