On Fri, 14 Apr 2000, John Wilson wrote:

> Actually, as far as I can tell XXDP uses DOS-11 labeling, so the first record
> of each file is 14 bytes instead of 512.  It really *has* to be something
> like this since most of the PDP-11 tape bootstraps have been around since
> DOS-11 days anyway, and they normally skip the first record of a bootable
> tape on the assumption that it's a DOS-11 label.  I hope I'm wrong though,
> I'm not that crazy about Dr.P.!!!

Aha! So *that's* why the first block is skipped. I never figured that one
out, I just know it is that way. :-)
By the way, does VAXen also skip the first block when booting from tape? I
don't remmeber if I figured that one out or not, and other people here
maybe already knows.

Speaking of which. Does all "modern" VAXen support booting from tape? I
know that the VAX-11 machines don't, except perhaps for the 750 (and
730?). Which is why there was a bootstrap program for TU80 tapes in the
manual for BSD. Just write it in on the FE system. It was a bit tedious
when I did that for the tenth time on the 8650 here, before we got a
bootable system placed on the disk. :-)

> It's really pretty rare to use unlabeled tapes under a DEC OS, their support
> for file-structured tapes is not bad at all, so it's better to hack the
> boot ROMs to live with labels, then hack everything else to live without
> them.

Yes, DEC was always pretty fond of using labelled tapes. And it really
works rather nice.

	Johnny

Johnny Billquist                  || "I'm on a bus
                                  ||  on a psychedelic trip
email: bqt@update.uu.se           ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol