The PDP-11/40 in the lab also had a TU56. When I wanted to copy between RK05 packs I ran RT-11 from DECtape. The TU56 was/is block addressable and behaves like a disk. Like the TU58, which was in all other respects pretty much a disaster. The total amount of time spent waiting by 750 and 730 system managers during a VMS upgrade must be staggering. Definitely a low point for the hardware designers. Was I glad that the 750 eventually learned to boot directly off an RA device! Verzonden vanaf mijn draadloze BlackBerry -toestel -----Original Message----- From: <Paul_Koning at Dell.com> Sender: owner-hecnet at Update.UU.SE Date: Tue, 23 Aug 2011 13:10:27 To: <hecnet at Update.UU.SE> Reply-To: hecnet at Update.UU.SESubject: RE: [HECnet] Can we hook this up to a VAX or something? Oh no. A TU58 is a joke device that connects via a UART; the driver for it is a pile of software that speaks a packet protocol over that UART to send/receive the data. The TU56 is a classic PDP-11 style DMA device, hooked to a Unibus interface. It looks somewhat like an old style disk interface (like the RK05 or RP04) except that you first had to seek to the required block number (by doing read block number operations until the right number shows up). Also, a TU56 is reliable, unlike a TU58.