Path: utzoo!news-server.csri.toronto.edu!cs.utexas.edu!usc!jarthur!nntp-server.caltech.edu!toddpw
From: toddpw@nntp-server.caltech.edu (Todd P. Whitesel)
Newsgroups: comp.sys.apple2
Subject: Re: ExpressLoad/System Disk (was:Re: System Disk configuration)
Message-ID: <1991Mar14.194809.959@nntp-server.caltech.edu>
Date: 14 Mar 91 19:48:09 GMT
References: <13219@darkstar.ucsc.edu> <29110017@hpfcdj.HP.COM>
Organization: California Institute of Technology, Pasadena
Lines: 28

jordan@hpfcdj.HP.COM (Steve J. Jordan) writes:

>Is Expressload always going or do I have to initiate it somehow?
>Isn't there a key you type while GS/OS is loading?

Nah, the keys is just to get a cute little logo in the 'Welcome' box.

Expressload is loaded if you have (i think) more than 512K, and it gets
first crack at any OMF executable (this includes ALL GS specific program files
like S16's, EXE, tools, inits, DA's, drivers, etc., except Cdevs which use code
resources). If the file has been expressed (there are utilities for developers
that will express a loadable program, and linkers that will generate a loadable
program that is already expressed) then Expressload can load parts of the file
by hopping to them directly instead of scanning the file sequentially like the
normal system loader does.

If the file isn't expressed or Expressload isn't in memory, then the normal
system loader (whose earlier versions were called "the loader from hell" --
try booting any of the old games or programs like deluxepaint II from floppy
and you'll see what I mean) processes the file. The normal system loader
searches for segments in the program file by scanning the file from the
beginning -- Expressload relies on a 'directory' that tells it where in the
file each segment starts. Expressload calls the system loader for a lot of
things that the system loader does adequately, and its major purpose is as
a performance hack.

Todd Whitesel
toddpw @ tybalt.caltech.edu