mguyott@mirror.UUCP (Marc Guyott) (02/28/89)
A couple of weeks ago I posted a note asking for some help finding a controller for a Seagate ST251-1 hard disk (which I incorrectly called an ST506) that I wanted to use in my AT clone. Here is a summary of the responses I received. > From: Mark Davis <davis@rho.cs.unc.edu> > > In article <23370@mirror.UUCP> you write: > >I have a seagate ST506 40MB 1/2 height internal hard disk (28ms access > >time) that I would like to use with my AT clone. ... > > OK, first a couple of nits. A Seagate ST506 is a full height, > 5Megabyte, 85 msec drive (One of the first on the market). > > Seagate makes the ST251-1, a half height, 40 Meg, 28 msec drive with > the ST506/ST412 interface (by far the most common interface), used on > most XT and AT computers with MFM or RLL controllers. > > >Can I purchase an AT compatible controller and use it with this drive > >in my AT clone? > > You don't say, but I presume that you already have your AT clone and it > only has a floppy disk controller in it. I know a lot of places sell > them that way, but you should open up your machine and make sure there > is not a hard disk controller there. Hard disk controllers use a > single control cable (34 connector) and a data cable (20 conductors) > for each drive. For example, if your computer had a WA2 controller > already installed, you see a 34 pin connector and two 20 pin connectors > unused on the controller board. There would also be a 34 pin cable > (probably with a twist in it) going from the controller to the floppy. > > On the other hand, the floppy controller may be on the mother board > and no controller cards may be installed. > > If you do not have a hard disk controller and you are happy with your > floppy controller, then all you have to do is buy a new controller. > You could even make an old XT clone controller work. However with > the 8 bit data path and high required interleave, you will sacrifice a > lot of your performance. If you machine is pretty hot (>= 10Mhz, 0 > waits) and you do a lot of disk I/O, I think the 1006 (or some other > 1:1 controller) would be a good investment. > From: lance@virgin.MV.COM (Lance Fraser) Here's a list of Western Digital controllers for your read enjoyment > > 1003WA2 16-bit/MFM/3:1/Hard-floppy > 1003VMM1 16-bit/MFM/2:1/hard only > 1003VMM2 16-bit/MFM/2:1/hard-floppy > 1003VSR1 16-bit/RLL/2:1/hard only/BIOS > 1003VSR2 16-bit/RLL/2:1/hard-floppy/BIOS > 1006VMM1 16-bit/MFM/1:1/hard only > 1006VMM2 16-bit/MFM/1:1/hard-floppy > 1006VSR1 16-bit/RLL/1:1/hard only/BIOS > 1006VSR2 16-bit/RLL/1:1/hard-floppy/BIOS > 1007AWAH 16-bit/ESDI/hard only/BIOS > 1007AWA2 16-bit/ESDI/hard-floppy/BIOS > From: Rich Hemmer <vampire@philabs.philips.com> > > The ST506 is the same drive as the ST251-1, but is listed as special to > certain vendors... ie PC Limited, Dell Corp. It is an MFM type drive and > should be run off of an MFM controller. However, it can be run off of an RLL > controller per some of the customer service people, but they do not guarentee > the performance nor will they say it is reliable... And here's some more information that I was able to dig up from the Universal Installation Handbook published by Seagate. The following are ST412 interface drives using MFM encoding at 5.0 MB/SEC. (msec) drive MB # heads Cylinders access time ST125 21 4 615 28 ST138 32 6 615 28 ST225 21 4 615 65 ST251 42 6 820 40 ST251-1 42 6 820 28 ST4038 31 5 733 40 ST4051 42 5 977 40 ST4053 44 5 1024 28 ST4096 80 9 1024 28 The following are ST412 interface drives using Run Length Limited (2,7) encoding at 7.5 MB/SEC. (msec) drive MB # heads Cylinders access time ST138R 32 4 615 28 ST157R 49 6 615 28 ST238R 31 4 615 65 ST251R 43 4 820 40 ST277R 65 6 820 40 ST4144R 122 9 1024 28 The following are SCSI interface drives. (msec) drive MB sectors access time ST138N 32 63,139 28 ST157N 48 95,015 28 ST225N 21 41,720 65 ST251N 43 84,254 40 ST277N 64 126,790 40 MFM CONTROLLER SELECTION The hard disc controller you use will affect the performance of the drive. To acheive full performance with an MFM dirve, you must use an MFM controller which operates the ST412/MFM interface at 5.0 MB/SEC. Operation of an MFM drive at data rates other than 5.0 MB/SEC, or operation of an MFM drive with an RLL controller is not approved by Seagate and will void your warranty. RLL CONTROLLER SELECTION To achieve full performance with a Run Length Limited (RLL) drive you must use an RLL (2,7) controller which operates the ST412/RLL interface at 7.5 MB/SEC. Only Seagate drives with an R appended to the product number are designed and certified for use with a Run Length Limited (RLL 2,7) controller. Note: early ST238, RLL drives did not have the R suffix. Operation of an RLL drive at data rates other than 7.5 MB/SEC, or operation of an RLL drive with an MFM controller is not approved by Seagate and will void your warranty. So, I hope some of you out there find some of this interesting. Thanks to all of the people who responded to my plea for help. Marc
ppa@hpldola.HP.COM (Paul P. Austgen) (03/03/89)
I wonder why operation of a RLL disc with a MFM controller would void a warranty. Seems like it could loaf along?