On 2011-07-14 21.49, Mark Wickens wrote: Are the MicroPDPs (desktop, deskside, rackmount) rare beasts? They seem to be of a fairly hobbyist-friendly size, although presumably they are less expandable (much like a VAXstation versus VAXserver I would imagine) I'd say no, they are not rare. But it's constantly getting more difficult to find machines as time goes by. No new ones are being built. You either need to find some place that is throwing out old hardware, and those are getting fewer, or else get something from another collector or a dealer. MicroPDP is a designation that don't really say anything about expandability, and is not really comparable to VAXstation vs. VAXserver. MicroPDP was a designation used for Q-bus machines. Originally they were prepackaged solutions, on which a "micro" version of an OS was designed to run on, but that was only to make a cheaper option available. The full software versions also runs just fine, and you can add any additional hardware on the machine. Traditionally, "large" PDP systems were the Unibus systems. They are much less "hobbyist-friendly" in size, yes. :-) The fastest machines produced by DEC were the MicroPDP systems, though. Johnny