I don't follow this list since I passed LISTSERV on to younger blood.
Andrew is correct that DD came from the operating system.  I used PCP
when I start which preceded MFT.  With MFT a job stream was loaded
into a reader and the operating system would read the JCL down to
a DD * or DD DATA statement which indicated that input was going to
come from the card reader.  The program would be invoked reading
a card at a time from the reader as needed.  After the step finished
or the end of data was reached, the operating system would resuming
reading more JCL.

HASP as stated as developed to overcome the delays caused by real time
reading of the cards.  It also allowed for multi-tasking.  HASP or the
full name, Houston Automatic Spooing Priority SYSTEM - II, was a
type III program.  Type III programs were IBM employee written programs
submitted and distributed by the Program Information Department (PID)
of IBM.  The order number of HASP was 360D-05.1.014.

Originally written by Tom H Simpson, Robert P Crabtree and Robert O Ray.
Submitted September 10, 1968.

To say the least, I learned HASP inside and out during my early days
of programming.  I could add that with MVS HASP was renamed to JES
(Job Entry System) with some controversy.  Was a throwback to its
roots, messages retained a prefix of HASP.

Jay

On 2/12/2009 2:25 PM, Kevin Parris wrote:
> Houston Automatic Spooling Program, origins at NASA (which used IBM
> systems) to avoid having to dedicate a line printer to a single
> application which might be crunching data and generating output even
> slower than the printer could print.  Later became Job Entry Subsystem
> 2, which as a name seems more oriented to the 'input' side of things
> (card reader machine) instead of the 'output' side (printers) which is
> where I always heard the focus had been - but "spooling input" and
> "spooling output" so that the physical devices are not dedicated to
> applications was the basic idea.
>
> That was all in the 1960's and my data center still had a working card
> reader/punch machine on the mainframe until around 1984 or so.  I edited
> the sysgen file to remove the definition myself after the machine was
> gone.
>
>>>> Pete Weiss <[log in to unmask]> 02/12/09 2:41 PM >>>
> At 14:35 2/12/2009 Thursday, Andrew Bosch wrote:
>> The DD parameter and the associated DD line is derived from the old IBM
>> JCL (Job Control Language). It's purpose was to provide data to batch
>> commands for processing within the batch job script.
>
> HASP running under IBM MFT or MVT (VM/CMS hadn't been invented, though
> predecessor had) on an IBM 7000 series e.g., IBM 7074.  HASP then was
> take over by IBM and productized as JES2.  Users' group called SHARE.
>
> I'm sure others will chime in :-)
>
> /Pete
>