>>Isn't this just a degenerative form of "diode matrix ROM"
>>Hardly a new idea I'm afraid ! 


>Wow, does *that* term ever bring back some fond (and not-so-fond)
>memories. 

>These remind me a bit of the PCB cards worth of diode ROM arrays in
>the Navy's  SPS-48 search radar computer back in the late 60's. As I
>recall, there were dozen or so of them. I'm sure that amount of memory
>would easily fit in a single EPROM chip today. :=)

Years ago I built several decimal to BCD coders built from 2 pieces
of stripline board 1 horizontal with 10 strips 1 vertical with 4 longer
strips and sandwiched between these diodes going from the bottom
to the top (all cathodes facing the same way) in the right places to
create the BCD code.
 
This way i could create BCD from some simple 10 position rotary
switches to mod a 27mc SSB transceiver to work on unusual and quiet
channels (the official channel switch generated only valid codes for
allowed channels to the PLL synthesizer).
 
Peter van Hoof
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