Article View: comp.sys.amiga.tech
Article #4791Re: AmigaDOS Filing System Block Format
From: Chuck McManis
Date: Thu, 09 Aug 1990 17:47
Date: Thu, 09 Aug 1990 17:47
44 lines
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2537 bytes
In article <2761@mindlink.UUCP> a275@mindlink.UUCP (Travers Naran) writes:
>1. What are the "words" refered to in the AmiDOS Tech manual? Long words or
>normal 16 bit words?
Each disk block is 128 32bit words. Normally words refer to 16 bit quanties.
>2. The Checksum is confusing, the manual says "Each filing system block
>contains a checksum, where the sum (ignoring overflow) of all the words in the
>block is zero." Huh??? I thought a Checksum was the sum of all the words in the
>block (not including the Checksum) ignoring overflow? Or does that sentence
>mean that when I add up all the words in the block including the Checksum, I
>should get zero ingoring overflow?
It means that if you add together all of the 32 bit longwords in a block the
sum will be 0. One longword is allocated as the checksum and can have any
value so to calculate the checksum you do something like :
block[CHECKSUM] = 0;
for (i=0, sum=0; i<128; i++) {
sum += block[i];
}
block[CHECKSUM] = -sum;
>3. T.SHORT and ST.ROOT, etc. where are these constants defined?
I just used diskedit (sectorama works as well) to figure them out. Also
check include:libraries/filehandler.h (or .i)
>4. How do I get a subscription to AmigaMail? I live in Canada and the RKM's
>only talk about the U.S. mailing address.
I would presume you mail to CATS in West Chester and ask for one. It is
about $25 US and there might be an extra charge for sending it to Canada.
Of course CBM Canada might get offended by the Commodore/Amiga encroaching
on its "turf" so there may be some internal political problems but that
is generally out of people like your and mine's control. I HIGHLY
reccomend the AmigaMail subscription. Around here it is known as the
"fourth" ROM Kernel Manual.
--
--Chuck McManis Sun Microsystems
uucp: {anywhere}!sun!cmcmanis BIX: <none> Internet: cmcmanis@Eng.Sun.COM
These opinions are my own and no one elses, but you knew that didn't you.
"I tell you this parrot is bleeding deceased!"
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!news-server.csri.toronto.edu!mailrus!uwm.edu!zaphod.mps.ohio-state.edu!brutus.cs.uiuc.edu!apple!sun-barr!newstop!sun!stpeter.Eng.Sun.COM!cmcmanis From: cmcmanis@stpeter.Eng.Sun.COM (Chuck McManis) Newsgroups: comp.sys.amiga.tech Subject: Re: AmigaDOS Filing System Block Format Message-ID: <140415@sun.Eng.Sun.COM> Date: 9 Aug 90 17:47:09 GMT References: <2761@mindlink.UUCP> Sender: news@sun.Eng.Sun.COM Organization: Sun Microsystems, Mt. View, Ca. Lines: 44