DEC 11/45 build - advice sought, parts requested possibly.

Tom Uban uban at
Fri Jul 8 17:32:58 CDT 2005

>>In terms of disk, RT11 can live just fine on floppies, but a disk is
>>nice, even an RL01 or RL02 (5MB or 10MB).  Older versions of RSTS are
>>OK on an RL02 or two; newer ones (v9, v10) may not fit on a system
>>with a single RL02.  2.9BSD doesn't really fit in 10MB - you can load
>>it, but there's no room for kernel sources.  Not sure about disk
>>requirements for v6, v7, etc., but 10MB might be OK.
>I'll go with either an RL02 or RA81.

You can fit v6 onto a single RK05 with just barely enough room for the
kernel source and enough space to compile it. It is tight but doable.
In order to run most Unix varieties, you will likely need a KW11 (M787)
line frequency clock, a full box of memory, the memory management (as
noted by Al), etc. The later BSD releases require a rather large amount
of disk space, depending on what all you install. They also become pretty
slow on the machines which do not support more than 128KW of memory.

>>With leaving the top of the rack empty for cooling (probably not a bad
>>idea in a non-machine-room environment), your options are severely
>>limited.  If it were my system, I don't think I'd even consider trying
>>to fit in a single rack, but I have a) empty H960 racks and b) space
>>to set them up.
>I have two other H960 racks, guess I'll have to add one to the /45 and 
>make it a dual bay system. The other H960 will probably go to the 11/34 

As long as you leave enough room for air to enter the top of the BA11-F, you
should be able to mount peripherals above the CPU bay. You will likely need
to leave the back, sides, or front panels off in order to allow a space for
the air to enter. DEC specified that no peripherals should be mounted above
the CPU because with the sides, back, and front panels in place, there isn't
enough remaining space to channel cooling air when a full size (e.g. RK05)
box is mounted in the space above. If you do mount a peripheral above the
CPU, be sure to space it up enough (perhaps 6") to allow room for air to
enter... It won't be as neatly dressed as with the sides/back/etcetera on
the rack, but it takes up half the space.


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