dtchen@cogsci.berkeley.edu (Super Dave Osborne) (02/19/88)
I will soon be acquiring an 85 meg MFM hard drive which happens to have 1250 cylinders. I have heard that the 'standard' Western Digital controller for the PC/AT only supports up to 1024 cylinders. Does anyone know of an MFM controller which will allow me to utilize all 1250 cylinders? The controller must be Xenix compatible. Also, what exactly is the difference between ESDI and the ST506 standard? Is it possible to use an ST506 drive with an ESDI controller? Thanks in advance. dtchen@cogsci.berkeley.edu ucbvax!cogsci.berkeley.edu!dtchen (whichever works)
cwwj@ur-tut.UUCP (Clarence Wilkerson) (02/19/88)
I believe that not only do the controllers not support the more than 1023 cylinders, but that only 10 bits are allotted in the standard calls to the controllers. A smarter ROM BIOS chip on the controller can claim more heads or more sectors to work around this problem.
lebherz@ncifcrf.ncifcrf.gov (Bob Lebherz) (02/20/88)
i need some advice about a problem with a pcs limited 286/8.
the pc is about 18 months old and i would estimate that it has
about 100 hours or less of operation. about a week ago the
system would not complete bootup after the initial selftest and
left an indication that the floppy disk controller was failing.
i contacted pcs limited and they told me that any wdc 1003-wa2
disk controller card would fix the problem. in the interim i
swapped out my brothers disk controller for the same machine
and it worked just fine. i ordered a card and installed it with
good results for about the first 10 minutes. at that point i
consistantly got errors trying to r/w the floppy drive (1.2 MB).
further testing would give me intermittant floppy access but not
at an acceptable level. the hard disk has been working without
any problems during all of the floppy errors.
i will be doing additional swapping and testing to verify that
there is a problem with the new board and another system but i
have some questions about the boards:
what is the difference of a rev x4 (old) and rev 11 (new)?
what are the jumper settings - all i can do is match the original
since there is no documentation with either of the controllers?
the component in position u102 (old) is not on the new board. is it
a mod by pcs limited to the original controller?
any help would be appreciated. up until now the pc has been very
reliable.
bob lebherz
lebherz@fcrfv1.ncifcrf.govneese@cpedev.UUCP (02/26/88)
>I will soon be acquiring an 85 meg MFM hard drive which happens to have >1250 cylinders. I have heard that the 'standard' Western Digital controller >for the PC/AT only supports up to 1024 cylinders. Does anyone know of an >MFM controller which will allow me to utilize all 1250 cylinders? The >controller must be Xenix compatible. It sounds like you are only interested in Xenix so you don't need to worry about the AT BIOS limitation of 1024 cylinders except at boot time. SCO Xenix, for example, uses the AT BIOS to load the kernel. If the Xenix kernel ever gets past the 1024th cylinder, you will not be able to boot. Also you do need a controller that has a WD2010, or something equivalent to be able to get past the 1024 cylinder hardware restriction. >Also, what exactly is the difference between ESDI and the ST506 standard? Is >it possible to use an ST506 drive with an ESDI controller? ESDI and ST-506 are two very different standards. No you cannot use an ESDI controller with a ST-506 drive otr vice-versa. Roy Neese UUCP @ ihnp4!sys1!cpe!neese
james@bigtex.UUCP (James Van Artsdalen) (03/03/88)
In article <-1025371@cpedev>, neese@cpedev.UUCP writes: > ESDI and ST-506 are two very different standards. No you cannot use an > ESDI controller with a ST-506 drive otr vice-versa. Not entirely true. OMTI makes two relavent controllers: the 8620 is an ST-506/ESDI controller and the 8627 is an RLL/ESDI. I don't really recommend these controllers for unix or xenix work (doesn't work with uPort, and I've heard tales of abysmal throughput with xenix), but should work fine for DOS. It's a 1:1 interleave buffering controller (price just under $200) with AT floppy support too. Adaptec also sells a similar controller, although I know nothing about it. -- James R. Van Artsdalen ...!uunet!utastro!bigtex!james "Live Free or Die" Home: 512-346-2444 Work: 328-0282; 110 Wild Basin Rd. Ste #230, Austin TX 78746