Accelerator boards - no future? Bad business?

I agree with you to some degree, but... Some components are just hard/impossible to find now - like old original disk drives (seen any RP0x's for sale recently?), or Able ENABLE's - and in any case running the disks is both non-trivial (power/heat) and risks damaging what are effectively museum pieces. So one is left with the choice of modern replacements, or nothing. And I'm not capable of building an RP0x, but building a board that uses an SD memory card to emulate an RP0x, that's within my grasp. And it takes a lot less room and power, to boot. Also, the _systems_ were designed to have upgrades installed, and did, BITD - many of which were not conceived when the machine first came out. E.g. our 11/45 at LCS wound up with 1MB MOS memory boards in it (much smaller and less power-hungry than the original memory), and high-speed LANs, neither of which were ever envisaged when the machine was built. I don't see that building, say, a UNIBUS USB interface now is really that different from building a high-speed LAN board BITD. I do agree that if you replace stuff that _is_ still available and perfectly functional (e.g. QBUS memory and processors), you might just as well run a simulator. But there's a lot of stuff that's not in that category (above). Noel