Using an ICL7660 to feed -5VDC to 4116 DRAMs?

Hi, all, I'm in the middle of getting two bare PET boards working, one static, one dynamic. I don't have great honking transformers lying around, so the easiest way to power them is going to be a bench-top DC supply. One thing that makes this a little easier is that I don't need to worry about cassette motor power in this configuration - no tape drives and no tapes. The static PET is easy - it has a few TO-220 7805s on it (which were removed to get the very tall heat sinks off for easier packing and shipping). I am not even sure I need +12VDC for that one - I don't think I do - just +5VDC at a few amps (also made easier because it came with no ROMs and no SRAMs, so I'm using one of Nicholas Welte's ROM/RAM boards that sits in the CPU socket). The dynamic PET, since it has soldered-in DRAMs, is a bit more complicated. Unless I care to remove the DRAM and fit another ROM/RAM board for the SRAM or adapt a 62256 in some other way, I need +12V and -5V for Vdd and Vbb on the 4116 chips. My question (after all this background info) is... does anyone have enough knowledge of the ICL7660 chip to give an opinion on how well it would work for supplying -5VDC? Looking at datasheets, the max draw I can find on Intel uP416s is 200uA @ -5VDC (along with all its other needs). It looks like the ICL7660 will provide up to 10mA @ -5VDC, but at some higher amount of inefficiency than at lower draws. 16x0.200 is 3.2mA, well under the max draw of the ICL7660, so I think I'm OK, but I wanted to ask other folks about this in case I'm overlooking some important detail. I do have a real C= keyboard that made it before the last plane, and I plan to build either a 74LS86 or 4066-based video adapter to drive a standard monochrome security monitor (that I saved from being discarded two years ago), so keyboard and video are taken care of (plus I have a "C=Key" board that I probably have time to assemble to try using a modern keyboard with). For a base PET, besides video and keyboard, the only other issue is power, thus my question. If the DRAM were socketed, I'd probably just pull it and use a 62256 in the ROM/RAM board and be done with it, but it might just be easier to feed this board +5V and +12V and synthesize the -5V, unless it turns out that I have a bad DRAM chip - then it's time to yank them like a bad tooth (though I _think_ I know where I can find a few 4116 chips on a shelf here if it comes down to just one or two chips). If I were home, it would be easy - I'd pull out a board from one of my PETs, drop these boards in there at least for testing, then see about mounting them in a box of some sort. Now, at least, the only C= stuff I have are these boards and a few loose parts (like 65C02s and 65C22s). One memory that's filtering up to the surface is that ISTR some order-of-DC-powerup requirement for 4116s, like don't apply -5V first or remove it last or some such. I plan to power the ICL7660 off of the +5V rail, but if there is a very specific order that really matters, I might consider running it off the +12V rail (with a 78L05 in-between) instead. Thanks for any input or observations on the ICL7660 and/or 4116s. -ethan -- Ethan Dicks, A-333-S Current South Pole Weather at 2-Jul-2008 at 08:40 Z South Pole Station PSC 468 Box 400 Temp -83.7 F (-64.3 C) Windchill -114.0 F (-81.1 C) APO AP 96598 Wind 6.1 kts Grid 58 Barometer 678.1 mb (10700 ft) Ethan.Dicks at usap.gov http://penguincentral.com/penguincentral.html