Glen Slick wrote:

The MSV11-JD and MSV11-JE are documented as being compatible with both the PDP-11/84 and Q-bus systems. The documented restriction is that the MSV11-JB and MSV11-JC are only compatible with PDP-11/84 systems and incompatible with Q-bus systems. http://www.bitsavers.org/pdf/dec/qbus/oemMicronotes.pdf uNote # 028 MSV11-Q/M/J MEMORY COMPARISONS MSV11-J ------- The MSV11-J has four versions, the MSV11-JB and the MSV11-JC which are used in the PDP-11/84 UNIBUS systems and the MSV11-JD and the MSV11-JE are used in either the MicroPDP-11/83 Q-bus systems, or the PDP-11/84 UNIBUS systems. All four modules use ECC memory for error correction, as well as using 256K bit MOS RAM parts on either a half for fully populated quad size module. NOTE: ----- NONE OF THE FOUR MSV11-J MODULES CAN BE PLACED IN A Q/Q BACKPLANE SLOT. IF THIS IS ATTEMPTED PERMANENT DAMAGE WILL BE DONE TO THE BOARDS AND TO THE SYSTEM. The MSV11-JB (M8637-BA) is a half populated quad size PMI memory module containing 1MB of memory. The second version of the MSV11-J is the MSV11-JC (M8637-CA), this is a fully populated MSV11-JB quad size PMI memory module containing 2MB of memory. These two module can not be used in a Q-bus system due to gate array incompatibilities, and can only be used in the PDP-11/84 systems which use the UNIBUS/PMI bus interface (KTJ11-A). The third version of the MSV11-J is the MSV11-JD (M8637-DA) which is a half populated quad size PMI memory module containing 1MB of memory. The last version of the MSV11-J is the MSV11-JE, (M8637-EA) which is a fully populated MSV11-JD quad size PMI memory module containing 2MB of memory. These last two modules can be used with either the MicroPDP-11/83 system which uses the Q-bus/PMI bus interface or the PDP-11/84 system which was mentioned above. Although the MSV11-JD and MSV11-JE are PMI memories they can be used in two other Q-bus configurations. (more details follow...)