VAXstation 3100 history (Was ... different)

From: <(>
Date: Thu Dec 2 13:55:38 1999

>>I still wonder why. The only thing I can think of is that either the driver
>>for the RC25 was removed or that VMS would no longer fit on an RC25 cartridge
>>as a boot volume. The drives used two platters, one fixed, one removable,

>Don't know about as a boot disk, but the RC25 is still supported.

Definitely not for the boot disk. The most basic VMS kit (that is,
without help pages, without libraries, certainly no DECWindows!) for VMS
6.1 won't fit in the 25 Mbytes available in a RC25.

6.2 "officially" requires more than 120 Mbytes for a basic installation,
but if you fool its installation procedure you can shoehorn it onto a
RZ23 (100 Mbytes)

>I suspect it was a question of RAM. Looking at the configurations for the
>11/725 and 11/730 it looks as if the 11/730 would hold at least a couple
>more MB.

Officially the 730 only holds 5 Mbytes. I don't know if there's any
way of extending this.

Remember also that the RC25, if the "fixed" platter is used as a system
disk, can be spun down to change the removable data platter. The host
OS needs to be aware that its system disk might be spun down, and it has
to be patient enough to wait for it to come back up. The PDP-11 OS's know
how to do this, and the last version of VMS to officially support the
725 with RC25 knows how to do this, but I don't know if they included
support for this in the more modern versions of VMS.

My 11/730, when I had it, ran VMS 4.6.

>I'm wondering if it wouldn't be possible to replace the RC25 with a 3rd
>Party SCSI controller. Though I'm not aware of any 11/725's in anyones

I know of a 11/725 still running a monitoring/logging application at a
nuclear power plant, booting from a RC25 under VMS 4.2. And yes, they
could upgrade to a SCSI drive and Unibus SCSI host adapter.

 Tim Shoppa                        Email:
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 Bethesda, MD, USA 20817           Fax:   301-767-5927
Received on Thu Dec 02 1999 - 13:55:38 GMT

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