[email protected] (Rick Fochtman) writes: > Most of those geometry-related "System Services" didn't exist! :-)
E4 channel command (extended sense) was introduced to start providing device characteristics (theoritically starting to minimize the amount of device information that had to be provided in system/IO sysgens). Then, FBA further drastically simplified (compared to CKD) ... eliminating having to know/specify anything ... recent comment http://www.garlic.com/~lynn/2010l.html#76 History of Hard-code Offsets Recently there has been some issues/nits related to FBA ... regarding efforts to migrate from 512 byte to 4096 byte sectors (which might be the closest analogy to all the CKD transitions) ... aka things like Linux Not Fully Prepared for 4096-Byte Sector Hard Drives http://www.osnews.com/story/22872/Linux_Not_Fully_Prepared_for_4096-Byte_Sector_Hard_Drives but it is the first major change since the 70s (other than some transitions involving total number of blocks/sectors supported). wiki page discussing some of the issues: http://en.wikipedia.org/wiki/Advanced_Format a lot of the discussion (aligned & multiples) in the above is almost identical to issues I faced when I did the page-mapped enhancements to cp67/cms filesystem (nearly 40yrs ago) ... some past posts http://www.garlic.com/~lynn/submain.html#mmap -- virtualization experience starting Jan1968, online at home since Mar1970 ---------------------------------------------------------------------- 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
