Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!ames!killer!csccat!jack From: jack@csccat.UUCP (Jack Hudler) Newsgroups: comp.sys.ibm.pc Subject: Re: 12-bit or 16-bit FAT entry Message-ID: <1350@csccat.UUCP> Date: 5 Jul 88 20:15:43 GMT References: <5930009@hpcupt1.HP.COM> Reply-To: jack@csccat.UUCP (Jack Hudler) Organization: Computer Support Corporation. Dallas,Texas Lines: 29 In article <5930009@hpcupt1.HP.COM> andrews@hpcupt1.HP.COM (Edward E. Andrews) writes: >How can I determine whether the FAT is using 12-bits or 16-bits per entry? >Is there a DOS call that specifically states: 12(16)-bit FAT, or does it >need to be infered (e.g. via DOS version [>3.2] or disk size [>32M])? You need the book MEMORY RESIDENT UTILITUES,INTERRUPTS, AND DISK MANAGMENT With MS&PC DOS. By Micheal Hyman, ISBN 0-943518-73-3, Published by Management Informations Sources, Inc 1107 N.W 14th Ave. Portland,Oregon 97209 +1 503 222 2399 This book goes into the disk rather well. A disk that uses a 12bit fat is usually a hard disk containing less than 31111 sectors per disk bytes 19 and 20 in the boot record. I personally dislike reading the boot record because there are a few disk managment drivers out there for partitioning hard drives that neglect in makeing a boot record on the non-bootable partition. I use the undocumented DOS call ah=32h dl=drive {0=def;1=a;2=b..} int21 ds:bx point to the drivers disk parameter block. Using this a disk system that uses 12 bit fats has less than 4087 for it's highest cluster - 1. Either way both have it's pit falls ;-). Jack Hudler -- See above (214)661-8960