Some legacy devices, e.g., 1301, had external controllers, e.g., 7631.

--
Shmuel (Seymour J.) Metz
http://mason.gmu.edu/~smetz3

________________________________________
From: IBM Mainframe Discussion List <[email protected]> on behalf of 
Tony Harminc <[email protected]>
Sent: Thursday, May 16, 2019 3:34 PM
To: [email protected]
Subject: Re: [External] Re: Ancient DASD connectivity

On Thu, 16 May 2019 at 12:50, Alan Altmark <[email protected]> wrote:


> Disk, tape, and unit record devices of the same era had discrete
> controllers.   Unit record CU (2821) was interesting in that it talked to
> devices that did different things: 1403/1404 printer and 2540 card
> reader-punch.  Clever of them.
>

Another way to think of the 2821 is as a bridge between "modern" (S/360)
channel protocols, and "legacy" (1401-style) devices like the 1403 printer.

Tony H.

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