The PM9 that I posted was from a 4 speed HF model Civic. You may be correct in your thoughts. (Warrick)

Note about attached files:
I do not know if it is normal for a DPFI pre-OBD computer to have the open areas for chips.

The PM5 + PM9 are essentially the same ECU. I think one may have been for the 4 speed and one the 5 speed, but I'm not sure. (blundar)

The PM5+PM9 used two distinct designs (kinda like the PG7) - the 88-89 Use an 83C154 while the 90-91 use a 66201. The 90-91 processor quadrant looks a lot like an OBD1 ECU.

Note about attached files:
I do not know if it is normal for a DPFI pre-OBD computer to have the open areas for chips.

%META:FILEATTACHMENT{name="pm9top.jpg" attr="" comment="PM9 top view" date="1085505656" path="pm9top.jpg" size="532694" user="warrick" version="1.1"}% %META:FILEATTACHMENT{name="pm9bottom.jpg" attr="" comment="PM9 bottom view" date="1085505743" path="pm9bottom.jpg" size="492973" user="warrick" version="1.1"}%

%META:TOPICINFO{author="blundar" date="1078510708" format="1.0" version="1.1"}% %META:TOPICPARENT{name="EcuFamilies"}% Essentially a PM5