obrien%rand-unix@sri-unix.UUCP (02/06/84)
From: Michael_OBrien <obrien@rand-unix> I did some specialized work to get the console cassette interface on VAX-11/750's into a useable state. The thing goes right into the CPU via a special, char-at-a-time interface that defaults to 19.2Kbaud. VMS can handle this, UNIX can't (except sometimes when UNIX is single-user). I'm an old so-and-so who can't stand owning a device I can't use, so I complained until someone led me to a PROM sitting in the middle of the street which, when used in the TU-58, implemented a byte-at-a-time acknowledgement (called MRSP) instead of the packet-level acknowledgement seen under standard RSP. MRSP only takes place if you initialize the thing with a special flag on in the command packet, otherwise it behaves like an old RSP PROM, so all the DEC stuff still works. If you do this, the driver in 4.2 can be convinced (via #define MRSP) to talk this protocol. 730's already have MRSP installed in them. The chip I found was not a 730 chip; it seems to be some intermediate version. No, I can't supply copies. Don't ask. I think if you duplicate the PROM in a 730's TU-58 and plug it into a 750's TU-58 it should work just fine. No guarantees. Some of the stuff in the 4.2 TU-58 driver is mine, like the new minor device that does write-with-read-verify, some error handling, etc. Basically it's not really a useful device except for those (like Berkeley, whom I really had in mind when I did the work) who have to do bootable distributions. Also old so-and-so's like myself who can't stand to own unusable devices. Now, if anyone has a 4.1 or 4.2 version of a driver for TU-56 DECtape I, I'd like to hear from you...
mab%aids-unix@sri-unix.UUCP (02/07/84)
From: Mike Brzustowicz <mab@aids-unix> While at USG, I wrote a TU-58 driver for the 750 which worked even while the system was loaded. (This was for the internal release 4.0, between system III and system V). I remember discussing with the Berkeley folks at that time what was necessary to get it to work, but as that was 3 years ago, I don't remember details. (had fun booting from it [but not a whole OS] and using it as a "file system" once, as I recall.) -Mike