[Coco] MM/1 Question

[Keith March]

Hello,

I have a question about the MM/1 computer from I.M.S. in the early 90's.

Can you tell me what the voltage is on pin 63 and 64 on the MM/1 backplane
buss?

The MM/1 tech manual says Plus 12 volts on pins 63 AND 64.

On the P8 & P9 (Old 12 pin AT style connector) connectors, I used an ohm
meter.

pin 3 on P8 traces out to pin 64 on the buss   and
pin 4 on P8 traces out to pin 63 on the buss

63 - PS8 Pin 4
64 - PS8 Pin 3

In the specs for the AT:

AT motherboard power supply pinout diagram @ pinoutguide.com
<https://pinoutguide.com/Power/MotherboardPower_pinout.shtml>

P8 - Pin 3 is Plus 12v
P8 - Pin 4 is Neg 12v

Can someone test the voltage on these 2 pins and let me know?

Maybe the tech manual is wrong.

Did the MM/1 use Neg 12v in the day?

Thanks a lot for your help.

Keith