DEC cartridge ID & ARTIFACS 440

Paul Koning paulkoning at
Wed May 27 18:56:05 CDT 2015

> On May 27, 2015, at 7:46 PM, Brent Hilpert <hilpert at> wrote:
> Thanks for the responses, Glen Slick provided a link to the manual, a pic we have of the stuff shows a drive matching that in the manual, so yes, RC25:
> 	Disk drive, dual platter - one fixed, one removable, 26MB per platter, ~ 8 inch disks.

Ah yes.  That made for a lot of fun in some operating systems, since it’s the only device where powering down one unit also powers down a second one as a side effect.  In RSTS, a pile of machinery was implemented to keep people from shooting themselves into the foot with that.  If I remember right, part of that was to allow the system to freeze, so you could have the system disk (boot disk) on the fixed platter and still be able to remove the other platter if needed.  This was done to allow selling RC25-only systems to a Navy, for use on submarines where there isn’t much space.


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