Not sure I'd concur with that latter. In analog terms the UNIBUS and QBUS are almost identical (which is why the same driver chips such as 8641's are used with both), and at the digital level they essentially identical (asynchronous interlocked request/response for read and write; interrupts using daisy-chained grant lines, with transmitted vectors; DMA, using the basic read/write protocol to transfer data). The (not very) big differences are that the QBUS multiplexes address and data onto a single set of lines, and the more complex multi-level interrupt using a shared single grant line; in both, more complex than the UNIBUS. Perhaps you meant 'easier to use', and that may be so, since most QBUS systems are much smaller (physically). Looking at the docs, I don't see any way to disable the on-board serial lines. You could probably cut etches to disable them, but I would advise against that, because there are easier/better ways to go. It should be quite easy to investigatwe where the problem is: look at the 'read receive 1 CSR' line, on pin 15 of E106 (with the 'halt' switch on). If that's not hopping around, the CPU isn't running. So then we'd need to look at the basic clock, and see if that's running; if so, then the CPU chip may be failed; we'd need to look at the PAX lines to confirm that. If that CSR line is active, there's a fault somewhere in the console serial line hardware; first step would be to feed characters into the machine, and see if they're coming out the UART. If you don't want to mess with all that, there are CPU boards on eBait for not too much money. (I'd be interested in buying the non-working CPU board, if you go that way.) Noel