Mandatory Engineering Change #1 -- 11/22/00


This effects "Tormenta ISA Card, Rev. A", 11/8/00

A silly error was found in the original design of the Tormenta Card. The 74HC688 address decoder IC must be replaced with a 74HC682 (or 74LS682) with pin 1 cut off (or lifted).

The boards were originally tested with a 74LS682 in place of the 74HC688, because there were no 74HC688's available to test with. A production problem was noted today, and the cause was located to the fact that this was the first time that the boards actually had been built with the 74HC688 part (as opposed to previous boards built with the on-hand 74LS682 parts).

The 74HC/LS682 has internal pull-up resistors on the inputs that the address select jumpers are connected to, whereas the 74HC688 does not.

There will soon be a Rev. B design and artwork available, correcting this flaw. We will use the 74HC688 and pull-up resistors, since the 74HC688 is far more readily available (and less expensive).

Until then, the Rev. A artwork is perfictly fine, as long as the above is noted.