On 07/17/2015 11:17 PM, tony duell wrote:
On the other hand if the +5V line did get too high it could have wiped out just about every IC in the unit. Ouch!. I've only ever had this happen once, and it was in a much lesser machine than a PDP11 (fortunately).
Many years ago, I managed to feed +12V into an Acorn Atom which was expecting +5V (the on-board regulators were bypassed to allow it to run from an external regulated 5V PSU, rather than the usual unregulated +9V).
Amazingly, it survived - although it makes me wonder if the experience dramatically reduced the lifespan of the TTL ICs though, even if they didn't immediately show any failure.
cheers Jules
