The following message is a courtesy copy of an article that has been posted to bit.listserv.ibm-main as well.
[email protected] (Tom Marchant) writes: > Indeed, one could build a 3390 with only one recording surface and an arm > that has 15 heads. > > IAC, the emulation of such a large number of tracks per cylinder would > probably not be too difficult. The real problem with that kind of > architecture would be the software changes that would be needed. from long ago and far away ... 16 data tracks & 1 servo track, head with 16 r/w data interfaces with 2 service track interfaces: http://www.garlic.com/~lynn/2006s.html#email871230 in this post http://www.garlic.com/~lynn/2006s.html#30 Why magnetic drums was/are worse than disks ? and related email in the same post http://www.garlic.com/~lynn/2006s.html#email871122 above eamil discusses that initial 3380 intertrack gap was 20 track widths ... 3380Es (double density) cut the inter-track gap to 10 track-widths (double the number of tracks per surface, double the number of "cylinders"). the following post http://www.garlic.com/~lynn/2006s.html#31 Why magnetic drums was/are worse than disks ? discusses 3330s had 20 surfaces (20 heads per "cylinder") ... 19 "data" surfaces & 20th surface for encoding positional information. the post after that http://www.garlic.com/~lynn/2006s.html#32 Why magnetic drums was/are worse than disks ? discusses that the 2301 "drum" was fixed-head device ... with head per track. actually there were two devices ... the 2303 "drum" that read/wrote single head at a time ... and the 2303 "drum" that read/wrote four heads in parallel (with four times the data transfer rate of 2303). the 2305 was a fixed head "disk" (platters with head per track on multiple platters ... as opposed to the 2303/2301 "drums"). above also shows my (incomplete) table of code names for different products. misc. past posts about getting to play disk engineer in bldg 14 (disk engineering) and bldg 15 (disk product test) http://www.garlic.com/~lynn/subtopic.html#disk -- 40+yrs virtualization experience (since Jan68), online at home since Mar70 ---------------------------------------------------------------------- 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
