[Simh] EXT : VAXstation 4000 Model 60

[Johnny Billquist]

On 2019-07-12 20:59, Mark Pizzolato wrote:
> On Friday, July 12, 2019 at 11:27 AM, Johnny Billquist wrote:
>> As far as I am aware, it was only some models in the 3100 series that used the
>> shorter SCSI commands in the boot rom, which caused issues with the boot
>> disk. However, I'm not sure that exact thing is the problem.
>> You might very well have some display issues that pop up in the boot monitor,
>> even though the system will boot perfectly fine from a larger disk.
> 
> On the older VS3100 systems (without large disk boot support), things would
> boot fine on larger disks as long as the pieces of OS code that are loaded in
> the early stages of the boot all happen to be located early enough in the disk
> drive.  Since you can't guarantee that all the needed files would be located
> early in the drive large disks were "not bootable".
> 
> Actually, the lack of guarantee would certainly be true for VMS systems
> that only could have a single file system on a particular drive, but Ultrix
> systems should be able to have an a partition that was sufficiently small to
> guarantee the ability to boot.

Yes, with Ultrix (or NetBSD) the problem is essentially non-existent. I 
was running NetBSD/vax on a 3100 for several years, with a large disk, 
and no problems.

Also, as soon as you're out of the boot rom code, there is no 
limitations either. So it's only for the early stages of the booting 
where this ever is a problem.

   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