CDC 6600 - Why so awesome?

Rich Alderson RichA at
Wed Jun 22 20:14:44 CDT 2016

From: Chuck Guzis
Sent: Wednesday, June 22, 2016 5:13 PM

> On 06/22/2016 04:46 PM, Rich Alderson wrote:

>> And it's rarely an armload.  Most programs fit into a deck of a few dozen
>> cards or so.  If you can't wrap a rubber band around the deck, you kept it
>> in the box.  (Oh, yeah, you bought cards in boxes of 2000.  About 16" long,
>> IIRC.)

> Well, if you were a serious programmer, major segments of code came in
> the drawer of a card filing cabinet (I don't recall exactly, but I
> believe one held about two boxes.)  However, then the idea was to get
> them onto tape before something dreadful happened, such as being
> subjected to a jam or being rejected because of a compare error in the
> reader.

Well, sure, but I was answering Swift's student-sounding question.  A card
drawer held slightly more than 2.5 boxes' worth of cards, but you wouldn't
carry that around, of course.

> I can recall on more than one occasion where an I/O clerk with a cart
> loaded down with card trays hit a loose trim strip in a raised floor.
> Mayhem indeed.  If you were smart, you drew a long diagonal across the
> top of the card deck with a felt-tip pen to at least give you some sort
> of clue about the order.

Different colors, different patterns, anything to help.

For that matter, cards were manufactured with different colors along the
upper edge (where the printing went in a keypunch) to allow for this kind
of separation.  That predates electronic computers, I would wager.

> There were SCCS type of systems even back then.   SCOPE had UPDATE,
> which corresponded to KRONOS MODIFY.  Each card was assigned a set
> identifier and sequence number, used as reference when editing.  Updates
> could be YANKed or PURGEd as necessary.

Oh, yes.  We had that kind of thing on big IBM gear as well.


Rich Alderson
Vintage Computing Sr. Systems Engineer
Living Computer Museum
2245 1st Avenue S
Seattle, WA 98134

mailto:RichA at

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