[Info-vax] The (now lost) future of Alpha.

[Johnny Billquist]

On 2018-08-08 02:19, Chris wrote:
> On 08/07/18 20:34, Johnny Billquist wrote:
> 
>>
>> Unix boot tapes for Ultrix (or BSD) is a rather special case, which can
>> be dealt with. All files only have a specific block size. No variable
>> sized records at all.
>> Try another tape...
>>
>> Johnny
>>
> 
> Distro qic tapes for Sun 3 were similar. Mostly tar format, but the
> first record is the boot block and an odd format, fwir...

Yeah. Same for Ultrix or BSD, or any PDP-11 bootable tape. First comes 
the boot block(s). They are all 512 byte blocks. Then you can have 
anything. On BSD (and I think Ultrix), there are a bunch of programs 
next, such as newfs and restore. All of those also have a fixed record 
size. Then comes the dump of the root file system. dump/restore also use 
a fixed block size. Then comes the tarballs, also a fixed block size.

So, if you just know the block size the different files use, then you 
can "easily" recreate the tape, with standard Unix tools. If you throw a 
file that have blocks with different sizes of the blocks, then no tool 
in Unix can help you.

   Johnny

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