Reposting, I'm a little worried these do not exist anymore. I've already tried every reseller on the planet. Generous Bounty for any of the following: HP 12920B Asynchronous Multiplexer : 12920-60001 Upper Select Code Data Board 12920-60002 Lower Select Code Data Board 12922-60001 Control Board Or HP 12920A Asynchronous Multiplexer: 12921-60001 Upper Select Code Data Board 12921-60002 Lower Select Code Data Board 12922-60001 Control Board Even single boards of any of the above would be a big help. Best, J