70's computers

On 10/24/2018 07:36 AM, Paul Koning via cctalk wrote: Well, no. They actually can do a lot more. They can do branching and simple arithmetic. We had a program to deal with damaged/deteriorating tapes. You could operate sense switches on the tape control unit to tell it when to give up on retries on a bad block and go to the next one. This allowed the operator to copy all the recoverable blocks from a bad tape. Once started by the CPU, this program ran entirely in the channel. The original scheme for disks was that the control unit + channel would be able to scan a range of disk tracks to find a record in which a string of bytes matched a pattern. This turned out to not work so well on larger systems as it could tie up not only the control unit but the whole channel for the duration of the search. In 1962-3 or so, when the 360 was designed, IBM had no idea how heavily the systems were going to depend on the disk drives. Jon