Xref: utzoo unix-pc.general:3021 comp.sys.att:6637
Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!n8emr!uncle!jbm
From: jbm@uncle.UUCP (John B. Milton)
Newsgroups: unix-pc.general,comp.sys.att
Subject: Re: Help with 2nd drive upgrade on 3B1.
Message-ID: <546@uncle.UUCP>
Date: 7 Jun 89 20:33:00 GMT
References: <1479@naucse.UUCP>
Reply-To: jbm@uncle.UUCP (John B. Milton)
Organization: U.N.C.L.E.
Lines: 58

In article <1479@naucse.UUCP> sbw@naucse.UUCP (Steve Wampler) writes:
[ problems with (Lenny & Gil)'s second HD board. ]

Sounds somewhat similar to the problems I am encountering with my board. I
should soon have it set up on a logic analyzer, so I may soon have some
suggestions. For right now:

1. Reinforce ground & +5
2. Shield it (what the heck)
3. Try some 2k pullups at the UNIXpc end of things on the high speed stuff.
4. Try a large cap across +5 & ground on the daughter board.
5. re-orient the long wires going across the bottom of the mother board.
6. Swap the drives (1<-->2)
7. Please post your findings

Error status register in the WD1010 (excerpt from HwNote13):
  Bit 7 Bad Block Detect. From what I can tell about how things are done on
    our systems, this feature is not used. We use a direct mapping method where
    the position of bad blocks is determined by the bad block table. If this
    gets turned on, it is some kind of glitch on the disk.
  Bit 6 CRC Data Field. This one deserves a direct quote:
      "This bit is set when a CRC error occures in the data
       field. With Retry enabled, ten more attempts are made
       to read the sector correctly. If none of these attempts
       are successful, the Error Status is set also (bit 0 in
       the Status Register). If one of the attempts is suc-
       cessful, this bit remains set to inform the Host that
       a marginal condition exists. However, the Error Status
       bit is not set. Even if errors exist, the data can be read."
    On our machiones, if bits 7, 5, 1 or 0 are set or if the error register is
    not zero!, or if there was DMA trouble, an HDERR message will be printed.
    This is extremely good. It means every time there is the slightest flicker
    in the data, you will get an error message. If you get only one, the error
    is probably transient and does not mean anything. You should NOT try to
    lock out the block! If you get a bunch of CRC errors, but a good read,
    this is probably a weak spot and should be locked out.
  Bit 5 Reserved. Always zero.
  Bit 4 ID not found. Like CRC, this bit is set when the ID field for the
    requested sector can not be found, or has a bad CRC.
  Bit 3 Reserved. Always zero.
  Bit 2 Aborted Command. Should never happen on our system. If you get it, it
    probably means BAD power line trouble.
  Bit 1 Track Zero Error. This is very bad, and usually indicates a very bad
    hardware failure in the drive, so you'll never see it until you get a
    second hard drive on your system :)
  Bit 0 Data Address Mark Not Found. Yet another thing not found.

Status 10 is bit 4 on, ID not found. This means it couldn't find the sector,
let alone what data is in the sector. The status 04 is confusing. This is
bit 2 on, aborted command. My remark above probably does not apply. It can
mean that the UNIXpc timed out waiting for something from the drive, and the
driver cancelded the request. Perhaps it was waiting for drive ready, or it
was waiting for ANY data to come in and syncronize the chip. Hmm.

John
-- 
John Bly Milton IV, jbm@uncle.UUCP, n8emr!uncle!jbm@osu-cis.cis.ohio-state.edu
(614) h:294-4823, w:466-9324; N8KSN, AMPR: 44.70.0.52; Don't FLAME, inform!