Polymorph wrote:
> On Feb 9, 11:51 am, A2Pro  wrote:
>> Hey, Alex!
>>
>> On Feb 8, 4:55 pm, Alex wrote:
>>
>>> Did you try the obvious: DigiKey?
>>> I got mine from there last week.
>>> P/N 269-3901-ND
>>> Even if everybody who got my kit decided to buy one, they probably
>>> still have a few left :)

>>     So, you have a 20 MHz part.  Before we go nuts arranging a group
>> buy, tell us, does it work in your card?  Any mods needed to the card
>> to get it to fully utilize this speed demon?

I'm wondering how Alex was lucky enough to get an item that DigiKey shows as 
non-stock.  And, yes, I'd also like to know if it works!

> As I'm an owner of an original Applicard, I am also curious if people
> think that the original Applicard could be modded to run at 20Mhz, or
> if the older design has some limitations that do not allow such
> ambitious undertakings.

That would be a definite "no".  By running 80nsec. DRAM (VERY
expensive at the 
time and hard to find in a 7-bit refresh flavor), replacing a few 74LS parts 
with HCT and trying a handful of Z80H (8Mhz. rated) chips I was able to get 
one of my Applicard running reliably at 10Mhz.  I doubt I could repeat it if I 
tried.  Faster than that just isn't going happen.  The timing margins for 
dynamic memory are way too tight.  8Mhz. is a fairly standard mod, though.  If 
anyone really wants to pursue this, let me know and I'll dig out my notes. 
For this, you need 100nsec. DRAM that refreshes on 7-bits.  Not all of it does 
and not all the different part numbers even specify it one way or the other in 
the data sheets.

Alex's card uses a far simpler design with modern parts and static RAM.  It's 
not out of the question that it could run at those speeds, but it's purely in 
the realm of experimentation.
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