cctalk Digest, Vol 52, Issue 32

Chuck Guzis cclist at
Sun Dec 16 13:58:39 CST 2007

On Sat, 15 Dec 2007 10:36:39 +0100 (CET)
> From: Christian Corti <cc at>

> All the drums that I have seen have fixed heads. There are adjusting
> screws for the distance between head and surface, but the head itself is
> then fixed with another screw after adjusting (we had to do this on the
> drum of our second LGP-30).

Univac made extensive use of flying head drums during the 1960's.  
Systems as late as the 1108 used them. AFAIK, they all had "FH" 
prefixes to identify them as such.

Bitsavers has the manual on the one I used on the 1108, the FH-880:

IIRC, the FH-880 spun quite fast.  On the other hand, the "big drum" 
on the 1108, the FASTRAND II, was a slow sewer-pipe of a monster.  
Here's a document that accurately describes it:

IIRC, the head movement was accomplished through an system of levers 
connected to solenoids that directly converted a binary code to a 
physical position.  

Regarding magnetostrictive delay line, bitsavers also has a 
collection of PB250 documents that might be worth a perusal:

Hope this helps,

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