Mystery system

Jim Stephens jws at
Fri Feb 5 00:10:09 CST 2016

On 2/4/2016 6:56 PM, Jon Elson wrote:
> On 02/04/2016 07:48 PM, Mike Loewen wrote:
>>    I'm trying to identify a system which appeared in "The Killer 
>> Elite" (1975), with a room full of tape drives and a couple of 
>> terminals:
>>    The drives appear to be IBM 3420s, but with an additional box on 
>> top, labeled "SMS".  The system itself doesn't appear in any of the 
>> shots. Some sort of IBM 370, perhaps?
> I'm thinking they might be 2420's.  They have a "9" label on the head 
> cover.  This is to distinguish 9-track from 7-track drives, I don't 
> think they put those labels on 3420 drives.
> The drive addresses are 5xx, meaning they are attached to channel 5 on 
> the CPU.  That is not impossible on a 360, but few 360's could handle 
> that many channels.  The cluster of 3270's also suggests a 370 system, 
> although they certainly could be used on 360's.
> The SMS boxes displayed the volume label of the tape to mount. 
> Mounting the wrong tape was a BIG problem in large systems, so a 
> number of vendors came up with these sorts of schemes to try to reduce 
> those errors.
> Jon
The 3270's would be tape operator consoles as well.  They could respond 
to tape mount messages as needed on those consoles.  The traffic at some 
point could be configured to be restricted to tape mounts.

Later tape libraries had a couple of 3270 ports connected and would read 
the mount requests, find the tape mount it and the reply to the mount 
message.  This may be in the era where they had consoles there and had 
to respond to the tape mounts manually, not sure.

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