I've looked, but I can't find anything more about DEFL. (The table says it was used in certain serial numbers of the core memory for the Stretch computer, so it

I've looked, but I can't find anything more about DEFL. (The table says it was used in certain serial numbers of the core memory for the Stretch computer, so it seems rather obscure.) Based on the speed, it's plausible that it is a type of ECL, but I don't know where the diodes would fit in. IBM had other names such as current-steering logic for ECL. Keep in mind that the 10ns speed doesn't mean you can run at 100 Mhz, since there are likely to be multiple levels of logic, as well as other delays. But it's still pretty fast.