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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

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!"