[comp.sys.mac.misc] difference between INIT, cdev, DA, and a startup utility

hairston@henry.ece.cmu.edu (David Hairston) (01/18/91)

Subject: Re: difference between INIT, cdev, DA, and a startup utility

[jeff@janus.Quotron.com (jeff) writes:]
[] could someone summarize the differences between the above???  how
[] does the system folder enter into all of this???

ohh, it's simple: INIT's are startup documents, cdev's can contain
INIT's and they're accessed through a DA called control panel.  INIT's
and cdev's typically are placed into the system folder in order to
be activated.  DA's are loaded into the system file (unless you use
a special DA (or is it an INIT?) to load DA's (and other things)) using
the Font/DA Mover.  a startup utility is typically an application
that is launched at startup and like a DA need not be in the system
folder.  a startup utility will typically provide some useful function
(hmmm, startup documents may do this also, this is getting confusing  ;)

okay (for real)!

INIT's (also called startup documents in Finder lists) are placed in
the system folder where they are accessed during system startup.  they
typically havve file type 'INIT' and do something useful (perhaps
patching a system deficiency, umm like SunDesk provides color icons,
there are a zillion examples).  they may steal space from the system
heap (or application heaps).

cdev's can often be thought of as run-time configurable INIT's altho
they may, in fact, not contain any INIT resources.  cdev's (control
panel devices) are accessed through the system DA "control panel"
and are meant to manage a specific task (umm, the mouse cdev controls
mouse parameters, the sound cdev does sound and so on).  they have file
type 'cdev'.  cdev's are also placed in the system folder so that the
control panel can find them (and if they have INIT resources they will
also act like INIT's).  in Finder lists these are also called control
panel documents (note: related Chooser documents for networked stuff).

DA's (desk accessories) are a pre-MultiFinder hack to allow extensible
functionality to applications.  a DA (file type 'DFIL', see related
font file type 'FFIL') are loaded into applications (or the system)
using Font/DA Mover.  they are typically accessed through the Apple
Menu (i.e. NotePad, Calculator and what have you).

a startup utility (i'm assuming you mean application) is designated
by a Finder menu/dialog to do its thing automatically at startup.
this can take various forms, including a RAM Disk application, or
a Finder substitute or a backgrounding screensaver application, etc.

note that all this will change (become simpler) with system 7.0.

hope this helped somewhat (it wasn't really technical ...).

  -dave-  
hairston@henry.ece.cmu.edu