ID'ing Q-Bus cards.

Paxton Hoag innfoclassics at
Fri Jan 2 14:35:23 CST 2009

> I have a PDP11/53, which on inspection contains 2x M7651:
> - One cabled to a same-sized card made by Logica and marked 3490/300
> - One cabled to a double-sized card marked 3350/304 (assuming Logica)
> Both these cards appear to be SCSI controllers, but does anyone know any
> more about them? And I'm wondering if there might be some hoops to jump
> through in their use, E.g. only support certain drives or require a patched
> O/S.

The 3490 is an IBM Tape Drive Subsystem and the 3350 is an IBM DASD
disk drive. both usually hooked up to IBM mainframes. Neither are

We went through a lot of these peripherals in the1990s. The last 3350
we got went to a collector. The 3550s were usually controlled by a
3880 which could handle up to 4 of  them, if I remember correctly.

It looks to me that the cards were for hooking up to these IBM
peripherals. Interesting set of cards. I have never heard of them.


Paxton Hoag
Astoria, OR

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