davis@clocs.cs.unc.edu (Mark Davis) (12/08/88)
The Seagate advertisement on page 36 of the December 5 Info world claims that the ST296 is part of the ST251 hard disk drive family (6 heads, 820 cylinders, 1/2 height 5.25", stepper motor head positioning). Of course, the 296 has a SCSI interface, but some encoding has to be used used between the on board SCSI and the disk itself. From other Seagate SCSI drives, it appeared that their SCSI drives were just the MFM drive with the SCSI adapter. However, for the 296, they would have to be using some exotic encoding technique (like ARLL) to get the almost 200% capacity increase. So, how do they do it: (1) Really not a 251 family member; more heads/ more cylinders/ different positioning method. (2) ARLL or similar encoding techniques. (3) some other method. Any facts or ideas? Thanks - Mark (davis@cs.unc.edu or uunet!mcnc!davis)
davis@clocs.cs.unc.edu (Mark Davis) (12/14/88)
In article <5754@thorin.cs.unc.edu> davis@clocs.cs.unc.edu (Mark Davis) writes: >The Seagate advertisement on page 36 of the December 5 Info world >claims that the ST296 ... > ... However, for the 296, >they would have to be using some exotic encoding technique (like ARLL) >to get the almost 200% capacity increase. >So, how do they do it[?] From the Seagate Product description, the drive is in fact part of the ST 251 family except they only make the 28ms average seek (higher speed) version. They get the 80 Megabyte capacity by (1) using RLL (regular 2,7 RLL). (2) using 34 sectors per track (instead of 26 for normal RLL and 17 for MFM). I have heard of a couple of 34 sector/track controllers, but they are not common. Apparently having your own controller on the drive has its advantages. Incidently, Seagate also has a 3.5 inch 80meg SCSI drive (ST1096) but there they added a platter to the ST151 to get the extra capacity and stuck with 26 sectors per track. SCSI is neat in that it lets the drive manufacturer better match the drive and the analog part of the controller. Of course ESDI is neat, too. Thanks for listening - Mark (davis@cs.unc.edu or uunet!mcnc!davis)
alz@tc.fluke.COM (Al Weiss) (12/16/88)
Here are some of the specs for the 251 and 296. These are from a Seagate rag that they will probably send to anyone describing most all of their products. It is Seagate Publication #1000 (I have Rev G, Aug 15, 88). Try calling 800-468-DISC or 408-438-6550. Personally though I am partial to Conner Peripherals, 408-433-3340, who have 20, 40, 100, & 200 meg drives. ST251 ST251N-1 ST296N Mb (formatted) 42.8 43.2 84.9 Sectors(512 byte)/Dr 83640 84254 165851 Sectors/Cyl 102 135 203 Bytes/cyl 52224 52736 103936 Sectors/track 17 34 34 bytes/track 8704 13312 17408 tracks 4920 3272 4920 cyls 820 630 820 discs 3 2 3 method MFM RLL(2,7) RLL(2,7) I/F ST412 SCSI SCSI