> -----Original Message----- > From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Noel > Chiappa > Sent: Thursday, April 14, 2016 10:28 AM > To: cctalk@classiccmp.org > Cc: j...@mercury.lcs.mit.edu > Subject: Re: Xerox Alto on eBay > > > From: Josh Dersch > > >> They are 12 sector 2315 packs. You have to duplicate it on a two drive > >> Alto, since the format is unique. > > > we're able to duplicate packs and write new ones out from disk images. > > (At the moment it's kind of cumbersome -- involving a PDP-11/44 with a > > 3mbit Ethernet board, a seriously hacked 2.11BSD kernel and a bit of > > luck > > You mean the RK11 controller can write packs that the Alto disk controller can > read? (As in, the low-level format - preamble, sector header, sector > checksum, etc, etc are all identical?)
No, they're as different as can be. The key is that we have a Xerox UNIBUS 3Mbit Ethernet board in the 11/44 (kindly provided by Al.) I modified the 2.11BSD kernel to support the 3Mbit board (there's already technically a driver but it was incredibly broken and I'm not sure it ever actually ran on a PDP-11), added support for reading/writing raw Ethernet packets using BSD sockets (and added support for that to the DEUNA/DELUA driver as well) and wrote a rough implementation of PUP BSP and the Alto CopyDisk protocol on top of all of that. It was fun! So we copy disk images to/from the PDP-11/44 over 3Mbit Ethernet to the Alto :). - Josh
