Hello guys, That's the info I found on the net from a 11/750 FAQ: "National Semiconductor Memory Systems: 1Mb memory boards. These boards have PWB 551109464-002 B PWA 980109464-001 D etched on them. They have a push-button switch for disabling the board, and a spare memory chip in a socket on the board. Board has green and yellow LEDS, which should normally both be on. Disabling the board causes the yellow LED to go out, and the red LED on the L0016 to come on, indicating bad memory configuration." Fred, what do you mean with "very wide boards" exactly ? These boards do have 6 fingers (hex wide) and fit into a usual UNIBUS slot. What are the differences between the VAX11 bus and the ordinary UNIBUS ? Can I find that out with a closer look to the pins ? Pierre __________________________________________________________ Mit WEB.DE FreePhone mit hoechster Qualitaet ab 0 Ct./Min. weltweit telefonieren! http://freephone.web.de/?mc=021201