16 Jan
2003
16 Jan
'03
6:28 p.m.
On Thu, 16 Jan 2003, David Evans wrote:
Don't. The moment you copy a tape file to disk, you will loose meta
information unless you use a program specifically designed to preserve
that information.
Johnny
Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: bqt(a)update.uu.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
On Thu, Jan 16, 2003 at 07:53:02AM -0800, Andru Luvisi
wrote:
Probably not. Repeated "dd"s will not produce the same result. This is the
typical error when not understanding that tapes actually are not a stream
of characters. (And also a good example when the Unix paradigm fails
pretty bad).
Each write to the tape device will create a block. You cannot do two
writes after each other to extend the block. You will instead get two
different blocks.
Boot tapes for VAXen (and PDP-11s) are expected to have 512 byte
blocks. Actually, the first block should be repeated twice, and this is
the primary boot block. After that you can put whatever you want. Most
primary boot blocks however also expects to read 512 byte blocks, which
means that the next file (secondary booter or the system itself) also most
often is written with 512 byte blocks.
maketape will pad each of "mtboot",
"mtboot", and "boot" out to an even
length of 512 bytes. The "cat | dd" method will not pad the first two
out.
Ahhh--of course. One would have to do a series of "dd"s in order to
get the padding happening. I discovered
this while trying to create a bootable tape image for simh.
I needed to emulate the maketape behavior for it to work.
That's not a bad idea. Perhaps I should just make a minimal bootable image
using simh or such, dd it to a SCSI disk, and then attach that to my 11/73.
Might be easier than endless futzing with the TK50.