Thierry Godefroy wrote:
>>> Again, I don't see why you exclude the possibility to bring the necessary
>>> signals to the daughter board via "flying" wires soldered on the
>>> corresponding pads under the Q60 PCB... I'd rather use a solder iron once
>>> and for all than loose performances with a kuldgy display driver.
>>
>> Because the wiring is HF-critical,
>
> 66MHz is not *that* high a frequency, and using short, flat wires ("câbles
> en nappe" in French: I don't remember the name in English) would likely do
> just fine.
Would be pure luck! Firstly, there are 80 MHz machines also. Secondly,
we are not talking a situation where both ends are terminated correctly
for a ribbon cable. The only reasonable way would probably be to use
wire-wrap lines, evenly glued to the mainboard, so the ground plane
still has some effect. I do not want to explain this to average users,
nor deal with the complaints if it only works "sometimes".
Mind you, in the late 68K / early PowerPC area, companies like Apple had
difficulties to make 66 MHz mainboards, even with multilayer PCBs and
ground planes! Ribbon cable wiring is far worse.
Peter
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