How fast does the -5V line start? #6
Description
From this post (emphasis mine):
-5V was the back-bias voltage for 3-rail DRAMs, in the era of 16kbit DRAMs. These used 5V for the interface, 12V to power the storage, and -5V to provide negative bias to the chip substrate. Without -5V, all 16384 storage transistors turned on at once, pretty much shorting the 12V supply to ground and destroying the chip.
You needed to ensure the -5V supply was working before starting the 12V supply. However as it supplied a bias voltage, it didn't need to source a great deal of current; 5ma was enough for a whole 64k memory! (the 12V supply was somewhere close to an amp)
Also, there's another curios thing in this post: -12V requirement of close to 1A (no idea what it can be used for other than RS232). Modern ATX PSUs can't usually provide more than 100mA on the -12V rail. So possibly, an optional -12V generator circuit can also be added to this design?