8 volts and 16 volts is correct. Frankly, I would stay on LOW side (but not below 7.5 volts). MANY systems burn up boards because they are towards the high side (it was a huge issue for early SOL-20's). S-100 boards use linear regulators, and many of them pushed those WAY too hard, to the point that they got so hot they charred the board. Some notable candidates includes the Tarbell double density controller card, the IMSAI SIO2-2 card and a number of memory cards. At 9 volts, the linear regulator has to dissipate 4 volts x {whatever current}. A board like the Tarbell double density board has one regulator for the entire board, about 60 ICs including some big LSI chips (179x FDC & Intel 8257 DMA) and ONE linear regulator that gets ridiculously hot at even 8 volts. The difference between 8 volts and 9 volts is 25% and makes a HUGE difference. Barry Watzman ------------------------------ Message: 25 Date: Sat, 28 Feb 2009 10:03:10 -0500 From: "Andrew Lynch" <lynchaj at yahoo.com> Subject: S-100 power supply voltage ranges To: <cctalk at classiccmp.org> Message-ID: <6FB56B9FDD5B49A78CDD0BB4DD3B4BF5 at andrewdesktop> Content-Type: text/plain; charset="us-ascii" Hi! What are acceptable voltage supply ranges for an S-100 power supply? I am assuming 115VAC input. My intended application is a small home brew S-100 backplane. I have seen the S-100 voltage rails vary but I believe +15VDC, -15VDC, and +9VDC would be sufficient. Herb's S-100 page lists the voltages as +18VDC, -16VDC, and +8VDC but I have seen other voltages used. Thanks and have a nice day! Andrew Lynch