RK07 Manual Dual Port?

tony duell ard at p850ug1.demon.co.uk
Sat Nov 7 09:17:31 CST 2015

[2 'Interface and Timing M7706 cards in an RK07]

> The existence of two separate wire list pages in the schematic, and a
> quick look at the M7706 diagram output signals suggests that this would
> *not* work - that the output lines of the two M7706 cards are wired
> together on a single-port drive and driven by ordinary TTL, and that a
> dual-port drive had different wiring on the backplane, even though the
> card cages are the same and the backplane itself is the same.

I am pretty sure you're rignt, this won't work and may damage the M7706 
boards due to TTL outputs being linked together. A quick look at the printset
shows that the multiplexers to select between the 2 M7706 boards in a dual
ported drive are on the dual port logic PCB,


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