On 08/28/2015 05:59 AM, Paul Koning wrote:
Especially if you didn't have the "direct seek" option. I had a one-card program that would do for (i=0; i<100; i++) seek_cylinder(i). That doesn't step track to track as you would expect; instead, it goes from track n to 0 to n+1, resulting in progressively wilder and slower seeks as n increases.
Yup, the one I worked with did not have the "direct seek option". What was interesting from a historical standpoint was the way in which the 1311 was used by Monitor II-D. IIRC, the first 25 cylinders were dubbed "work cylinders" with no formal filesystem. The remainder was used for more-or-less permanent storage of programs--not so much as a data store.
The CADET I worked on did have the Indirect Addressing feature, which I believe was required to run Monitor II-D. Hard today to think of an addressing mode as an optional ($$$) feature. The Model II had an index register.
I can still remember many of the 1620 numeric opcodes. Strange, considering that I can't remember where I put my keys or what I had for breakfast...
--Chuck
