Path: utzoo!attcan!utgpu!watmath!clyde!att!chinet!ward
From: ward@chinet.chi.il.us (Ward Christensen)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Making a PC-XT hard-disk bootable again...
Message-ID: <7352@chinet.chi.il.us>
Date: 2 Jan 89 16:19:00 GMT
References: <13186@duke.cs.duke.edu>
Reply-To: ward@chinet.chi.il.us (Ward Christensen)
Organization: Chinet - Public Access Unix
Lines: 24

I've done no exhaustive study of this (I never DO exhaustive studies ;-)
but I have determined some tricks to make SYS work without reformatting
- but of course these ARE "advanced topics" as you said you would
handle:
  Using something like Norton Advanced Utilities, ensure that (1) there
are sufficient clean clusters @ the front of the disk, i.e. if IBMBIO
and IBMDOS are a total of (making this up...) 34 clusters long, be sure
clusters 2-36 are open.  At leeast in some early DOSs, they HAD to be
contig.  
  Then make sure the first 3 directory entries are not only available,
but ZEROED.  I believe I zeroed the first 4 (not sure 3 is enough).
  Then boot the floppy and sys the hard disk.
  Also make sure FDISK has the partition flagged as "active" - that is
the single most common reason an "otherwise OK hard disk (accessible
from A: booted floppy)" won't boot.
  CAUTION: zeros in the first byte of any directory entry signals DOS
"end of directory".  CHKDSK also sees it as the end.  SO be sure to go
back and patch in an E5 so the remaining dir entries will then again be
seen.
  These hacks have always worked for me - SYS seems to say "OK, the
space is open, the directory is empty, GO FOR IT" when in fact you were
just "kidding it" in a non-destructive way.
  "For advanced hackers only - not responsible for mistakes YOU make or
any I may have made in describing this technqiue" ;-)