OK, just to give you folks a taste. Back in the day (late 60s) one of the machines I used was a CDC 3400. Core memory, 36-bit word, no disk. OS loaded from tape. Great 607-C tape drives that were the epitome of electromechanical design. Had two vacuum columns, on either side of the R/W head, with constantly (counter)rotating slotted capstans, Tape floated on air over the capstans, and could be stopped/started/reversed in milliseconds, with a shoe-shine motion in the vacuum columns. Reels only moved when they had to to refill/empty the columns. Could even read & write in reverse -- which was critical to my hack. Wrote a text editor that used two tape drives with the front of the file on one, tail end on the other. IIRC, each line of text was one record. Could move forward or backward through the file reading one drive, writing the other forward or reverse as appropriate. Insertions or deletions of any size in the middle were trivial. Try that without random access secondary storage! :-)
Posted on: Thu, 17 Jul 2014 06:07:19 +0000