I got in the 11/53 running Micro/RSX. The 11/53 has an H9278-A backplane. According to Megan's fieldguide the first 3 slots are Q22/CD and the last 5 slots are Q22. What does that mean? At this moment, this is the configuration: slot 1 rows 1-4: M7554-02 - 11/53-PLUS CPU slot 2 rows 1-2: M3106 - 4-line async EIA MUX slot 3 rows 1-2: M7546 - controller for TK50 slot 4 rows 1-2: M7555 - RQDX3 rows 3-4: ??? All other slots and not mentioned row positions are empty. In slot 4 rows 3-4 is a card with just one 8-pos DIP switch three 16-pin DIL resistor chips and some decoupling caps. At the top are two BERG connectors, one 40 pin and one 50 pin. These two flatcables connected to an external unit, brandname Dynafive. Inside that box are several "Dynafive" boards and one board of "VGScientific". The rear of the box has several BNC connectors with markings that pops 'video' stuff to mind. Like H-sync, Green-in, Red-in, Green-out, etc. This box and the 11/53 were connected to eachother. On the disk in the 11/53 I found .RNO files that describe the VGS5000 and how to use the application (something with spectral analysis). So far for the system description. Now my question. 1) Can I remove that ??? card 2) Put a DELQA or DECNA at the same position? I seem to remember that the RQDX3 must be the last device in the backplane for some reason. So, should the Ethernet card go in slot 4 rows 1-2 and should I move the RQDX3 to slot 4 rows 3-4? TIA, - Henk