Re: ZipGSx Upgrade Questions (I've read the FAQ's)

[Rubywand <rubywand@swbell.net>]

Marvin Miller writes ...
> 
 ....

> About the ZipGs running stock - tried that, I think it wants to go
> faster than 7Mhz. Myself, I was hoping for 15 at least.
>

     10MHz is 'fast enough' to comfortably run System 6.0.1 and practically
all current IIgs applications. 15MHz is roughly the upper limit for reported
ZipGS upgrades.


 
> About the 74F00, I couldn't find it in the FAQ but I did pull it up
> several times through DejaNews. Here's a transcription...;
> 
> "I've done some other reading up and apparently ZipGS's can be pushed
> beyond 12.5Mhz, however with some work on the end user's part.  The
> Zip will need to have the 74F00 replaced with 74HC00, which is $.045
> from Digikey. Also, the SRAMS will have to be changed to faster ones,
> at least 15ns."
> 
> End transcription. I've seen this in a couple of places with no
> description whatsoever about what this mod accomplishes. The general
> consensus is that if your aiming for top speed, do the mod.
>

     Based upon Wayne's information and the info quoted from David, it looks
like the recommendation is valid. Replacing the 74F00 with a socket (for
plugging in the 74HC00) seems like a good idea.



> Also, it's important to note that the DigiKey part number given in the
> FAQ for the socket adapters seems to be the wrong one, being A502-ND.
> I'm not certain, but I know in my case I need the A504-ND
>

     Think you may have it backwards. A current Digi-Key catalog shows the 
A504-ND as an adaptor for using 28-pin 600 mil chips in 300 mil sockets. To
use skinny 300-mil 28-pin RAM chips in 600-mil sockets, you would want the
A502-ND.

     To help avoid confusion in the future, the FAQs for Accelerators has
been changed to be a bit more explicit about the adaptor and to refer users
to the adaptor maker, Aries, and to the Aries part number.  


 
> My understanding of the motherboard power issues was that a Rom 03 had
> most of the mods done.
> I haven't looked at the FAQ yet as I've been
> trying to get the parts for zip mods ordered.

     FAQs information about the power mods does note that the ROM 3 is
supposed to have better Slot area power distribution and may not require the
motherboard mods.

     The main concern would be with your power supply leads. Since you plan
to run with an accelerator above 10MHz and plug in other boards to enhance
your IIgs, it is likely that the leads coming from the standard IIgs power
supply will be too skimpy (as outlined in Q&A 005 on the Power Supply and
Cooling page http://home.swbell.net/rubywand/Csa2POWER.html#005 ).


 ....

> On the oscillator front, you mentioned;
> 
> >The oscillators on page 144
> >of catalog P004 (CTS Reeves MX045) look pretty good. You want a "standard
> >output" model.
> 
> What catalog is this? I checked page 144 in the Digikey one (full
> catalog, pdf format) and couldn't find it.
 ....

     There may be differences between the on-line and print catalogs. Just
look for CTS Reeves oscillators (or Digi-Key part numbers like CTX120-ND,
...).  Oscillator selection does not appear to be critical. My reason for
suggesting the particular brand is mainly a lower specified current
requirement.


 ....



Rubywand