Re: Upgrade conundrums...

[rubywand@aol.com (RUBYWAND)]

In article <4u2buj$4ne@nyx10.cs.du.edu>, wbaguhn@nyx10.cs.du.edu (Will
Baguhn) writes:

>David Empson <dempson@actrix.gen.nz> wrote ...
>>....
>>The ROM 3 has less noise generated by the motherboard, and consumes
>>somewhat less power, so it will work more reliably at higher speeds,
given
>>the same I/O cards.
>
>Here's an idea... would a heat sink on the processor help?  Something...
>486ish, but smaller.  If a ground lead is attached, it should
>also block out noise a bit, so it's more an issue of electrical noise
>rather than RFI.
>

     The ROM-03 board is said to have a less noisy Slot power bus mainly
because the power traces are heavier/wider. Since there is less resistance
between boards and the power supply connector, there is less voltage drop
(E = I x R)  and less noise. 

     Altech, Sequential, etc. cannot, reasonably, guarantee that boards
like a 10-15MHz Zip-GS or Second Sight will work in any IIgs because
systems vary widely in terms of noise generation. Minor-looking
differences in Slot power trace thickness, variations in power supply lead
capacity, resistances at the power supply connector, number and location
of power-sucking plug-in boards, and accelerator speed are factors which
separate glitchy systems from those which are glitch-free.

     Anyone who plugs a 10MHz or faster Zip-GS and/or a Second Sight card
into a stock IIgs is 'rolling the dice' at pretty poor odds. The power
supply leads-- +5V, +12V, and Gnd-- should be fattened to #12 gauge.
ROM-01 owners should also run #16 gauge leads for +5V and +12V on the
motherboard from the PS connector to Slots 3 and 7.

     If a uP chip is running very hot, some kind of heat sink is a good
idea. Mainly, with or without a heatsink, you want some air moving across
the board. A heat sink will have little effect on suppressing noise or
shielding the uP IC from noise.. 


Rubywand