Article View: comp.os.msdos.programmer
Article #5710Re: MsDos DISKCOPY: What bytes are copied, what bytes are not?
From: Bob Eager
Date: Thu, 11 Apr 1991 10:20
Date: Thu, 11 Apr 1991 10:20
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1855 bytes
In article <28023A20.23271@orion.oac.uci.edu>, ece134@venice.eng.uci.edu writes:
> I was wondering if "diskcopy" copies all bytes of all sectors
> (9 on 360K floppy disk, 15 on 1.2M floppy) on the first 2 tracks
> (track 0 and 1). I have the believe that certain bytes are
> not copied. Could anyone tell me
> a) if I am right or wrong
> b) what bytes are not copied (in case I am right)
DISKCOPY will copy all bytes of all sectors as specified, unless you are
using DISKCOPY on DOS 4.x or OS/2. On these systems, it does not copy
the eight bytes immediately before the bootstrap code in the very first
sector. You can locate these by looking at the boot sector with DEBUG, and
finding the destination of the JMP instruction at the front. Eight bytes
immediately preceding this jump destination are the disk serial number and
are meant to provide a measure of uniqueness to cut down on mistakes when
disk swapping (e.g. during a single-drive copy).
It is possible that earlier OEM versions of DOS do this trick too.
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Bob Eager | University of Kent at Canterbury
| +44 227 764000 ext 7589
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!usc!snorkelwacker.mit.edu!bloom-beacon!eru!hagbard!sunic!mcsun!ukc!harrier.ukc.ac.uk!zodiac.ukc.ac.uk!cur022 From: cur022%cluster@ukc.ac.uk (Bob Eager) Newsgroups: comp.os.msdos.programmer Subject: Re: MsDos DISKCOPY: What bytes are copied, what bytes are not? Message-ID: <22202.28043858@cluster@ukc.ac.uk> Date: 11 Apr 91 10:20:08 GMT References: <28023A20.23271@orion.oac.uci.edu> Organization: Computing Lab, University of Kent at Canterbury, UK. Lines: 22