Anne & Lynn Wheeler wrote:
the other issue is that ckd dasd from the 60s ... traded off i/o thruput with extended (& multi-track) searches for real memory use ... i.e. more real memory intensive tended to cache indexes to specific disk location ... while vtoc & pds multi-track search spun the disk to find location. Some of the IMS ccw programs took this to the extreme with long ccw programs searching and finding fields in disk-based index structures ... which then were read and used for further searching ... all in a single channel program.
This reminds me of a question that you might have the answer to. The 2314 and 3330 controllers (and Memorex 3330 and 3350s) supported a Search Key and Data opcode. I used this out of curiosity to write a small card-format editor doing I/O based on sequence numbers in the data. As expected, it used little CPU time, but tied up the channel. Did anyone ever find a productive use for data search? Considering that IBM dropped it as a standard feature on the 3350, and completely on later models, I doubt it.
Gerhard Postpischil Bradford, VT ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
