Seymour J. Metz asks: > I need a reference for Wikipedia as to whether the cells on a 3380 > only relate to error checking or whether they actually reflect the > physical layout of the track.
I have found it. And, now that I have found it, I remember it. This getting old **** is for the birds! According to a paper in the IBM Systems Journal, Volume 25 Issue 3.4 (1986) on pages 274-305, titled "Impact of memory systems on computer architecture and system organization" --. > A sector on a modern 3380 disk is about 512 bytes long After reading that, I remembered more in the 1981 discussion with Ed Daray and Jack Gelb. There was something mentioned about what they called "overhead bytes" (that was not the usual inter-block gap requirement, they said -- that was there, too, but completely invisible, which was the point of a cellular device) and "packing" and other fine-sounding mumbo-jumbo and hand-waving to the effect that the blocks actually written on the track were not _exactly_ a multiple of the cell size. The cell size was the unit of allocation of track space, but they were not written as 32-byte blocks (nor exactly some multiple thereof), but (as far as the data one could actually plan on being able to occupy space) it was made to LOOK LIKE the physical blocks were 32 bytes but there was no IRG. That is exactly how 3380s and 3390s behave. Enough said. I think that settles it. The 3380 _WAS_ an FBA device under the sheets. But I still don't have an authoritative reference for you (other than that Systems Journal article). -- WB ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
