Re: PseudoDisk ][ and IIGS

["sicklittlemonkey" <Nick.Westgate@gmail.com>]

I hope (1) works, as it sounds a lot simpler!

Cheers,
Nick.


Alex Freed wrote:
> A bit of bad news. I tested the PD on a IIGS and it doesn't work well.
> Half the time it doesn't work at all. The other half I do get to my
> selection
> program prompt. Nibble images work after that but ProDOS mostly fails.
>
> So I looked at the Apple IIGS TechNotes  #68 and found 2 things:
>
> 1. Recomendation to delay driving the data bus by 60 nS after the PH0.
> For example by using LS TTL circuits that provide about that much delay.
>
> My CPLD is pretty fast - 10 nS. So I'm clearly violating this condition.
> To comply with the recommendation I would need to wire at least one extra
> signal from the slot - 7M.
>
> 2. Apple also warns that
> "Since the Apple II expansion slots were designed with only one ground pin,
> complex expansion cards sometimes have problems with excessive ground
> noise--
> especially in the IIGS, where the signals typically have faster rise and
> fall
> times."
>
> They suggest using a lot of capacitors on all unused power lines.
>
>
> One or both of the above may be the reason for the flaky behaviour I've
> observed.
> 
> 
> 
> -- 
> -Alex.