Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!watmath!clyde!burl!ulysses!allegra!mit-eddie!genrad!decvax!ittatc!dcdwest!sdcsvax!sdcrdcf!ucla-cs!cc1
From: cc1@ucla-cs.ARPA (UCLA Computer Club)
Newsgroups: net.micro.amiga
Subject: Re: Unix/AmigaDOS wars (again)
Message-ID: <12401@ucla-cs.ARPA>
Date: Sat, 3-May-86 14:01:25 EDT
Article-I.D.: ucla-cs.12401
Posted: Sat May  3 14:01:25 1986
Date-Received: Tue, 6-May-86 07:12:07 EDT
References: <8604270910.AA26871@cory> <620@jade.BERKELEY.EDU>
Reply-To: occ4mgk@oac.ucla.edu, cc1@ucla-cs.UUCP (Michael Gersten)
Organization: Ucla Computer Club (disclaimer)
Lines: 37

In article <620@jade.BERKELEY.EDU> mwm@ucbopal.UUCP (Mike (I'll be mellow when I'm dead) Meyer) writes:
>In article <8604270910.AA26871@cory> dillon@CORY.BERKELEY.EDU (Matt Dillon) writes:
>>(3)	Linked list sector's went out a decade ago.  Only commodore was
>>stupid enough to use linked list sector's in their disk format.  Get
>
>Sorry, but Commodore weren't the only people to use linked list sectors. DRI
>slow and fragile. TRSDOS has (had?) the same problems. But for a real laugh,

*** GGGRRRRRRRR ***

I don't like TRSDOS, but I will defend it were it deserves it (Besides,
NeWDOS uses essentially the same system)

A TRSDOS directory has one sector for the disk allocation map, one sector
for all the file hash codes (quick yes/no test), and 8 more sectors with
8 files each. Each entry stores the name of the file and 4 extents
(phisically continuous disk space), plus a pointer to the next entry
(if there are more than 4. Very few files need more than 2 or 3).
The File Control Block (sort of like a FILE structure) contained the
4 most recently used extents (in memory). Seeks were fast--they just
updated pointers, and read the directory if the extent information
wasn't in memory.

TRSDOS has a fast file system. Disadvantages?
1. No directory support. Enough space to put it in, but its not in.
2. Limited # of files. NeWDOS 80 is best, but it maxes at 222 files.
   (But you could make that 222 per directory (ugg)
3. Granule allocation. 3, 5, or 6 sectors per gran in most systems.
   (Everyone but NeWDOS refused to let a gran cross tracks. NeWDOS
   used 'lumps' (logical tracks) and kept the original 5 sectors per gran.
   But you could say 8 grans per lump for large drives.

Incidently, I still think granule allocation beats sector allocation.
Much less fragmentation.
		Michael 'Floppies are cheap' Gersten.
-- 
Views expressed here may not be those of the Computer Club, UCLA, or anyone.