The EAV specs are taking the high 12 bits of the head field in CCHHR field in count record to extend the cylinder field. The first step allowed 4 * 64K cylinders, the second step currently allows 16*64K cylinders, it will eventually allow 4K * 64K cylinders.
On Tue, Jan 9, 2018 at 4:28 PM, Steve Smith <[email protected]> wrote: > The reason for the games is that the cylinder number has traditionally > been a half-word... Mod-"27"s went as far as possible treating it as a > signed number, and Mod-"54"s to the unsigned limit. > > If IBM can't move away from this archaic dependence on defining > imaginary geometries of imaginary DASD, why don't they invent a new > imaginary device with say 127 tracks per cylinder, 128K bytes/track? > With 64K tracks, you could store almost a terabyte on one volume. > > sas > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO IBM-MAIN -- Mike A Schwab, Springfield IL USA Where do Forest Rangers go to get away from it all? ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
