[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Various Accelerators

sfahey wrote:

  To: Michael J. Mahon
On 9/2/08 2:47 AM, in article 7qKdnQ0NFasUciHVnZ2dnUVZ_rjinZ2d@comcast.com,
"Michael J. Mahon" <mjmahon@aol.com> wrote:


The early ones (I think the first 8MHz production run) suffered from
unreliable cache SRAMs *inside* the potting, and thus fatal.  An 8MHz
Zip Chip that still works is almost certainly not one of this lot.  ;-)


I have a couple of both, that still work. I'd just say you're less likely to
fatalities with the external cache version... easily identified by the tiny
bubble or blister on the bottom of the ZipChip.


Right.  I think that the earlier run used flip chip packaging for the
cache, and the potting material turned out not to be as "hermetic" as
they hoped.

The later runs with separately packaged cache SRAMs (and perhaps other
components as well) apparently benefited from their better chip seal.

-michael

AppleCrate II: An Apple II "blade server"!
Home page:  http://members.aol.com/MJMahon/

"The wastebasket is our most important design
tool--and it's seriously underused."