Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!linus!philabs!cmcl2!seismo!ut-sally!pyramid!amiga!dale
From: dale@amiga.UUCP (Dale Luck)
Newsgroups: net.micro.amiga
Subject: Re: Electronic Arts Copy Protection
Message-ID: <732@amiga.amiga.UUCP>
Date: Sat, 22-Feb-86 14:39:31 EST
Article-I.D.: amiga.732
Posted: Sat Feb 22 14:39:31 1986
Date-Received: Mon, 24-Feb-86 20:50:33 EST
References: <1323@caip.RUTGERS.EDU> <1450@gitpyr.UUCP>
Reply-To: dale@tooter.UUCP (Dale Luck)
Organization: Commodore-Amiga Inc., 983 University Ave #D, Los Gatos CA 95030
Lines: 41

In article <1450@gitpyr.UUCP> lbg@gitpyr.UUCP (Lee B Grey) writes:
>On page 2-10 of the V. 1.1 ROM Kernal Manual, there is a CAUTION:
>
>Section 1.2 describes the lowest level graphics interface to the system
>hardware.  If you use any of the routines and the data structures described
>in these sections, your program will essentially take over the entire display.
>It will not, therefore, be compatible with the multi-window operating
>environment, known as Intuition, which is used by AmigaDOS.
>
>End-quote.

I think I need to clarify this:
The section that this caution appears in is the display/viewport
area of the manual. The data structures in question are:
View,ViewPort,RasInfo. 95% percent of the programmers out there
never even bother with this since intuition manages them for you.
The routines in question are InitView,InitVPort,MakeVport,MrgCop.
Intuition provides these capabilities with its Screens. By using
the intuition functions you can get nearly the same results.
The low level routines were designed for a single program to manage
since they do not suffer the overhead of multitasking protection.
That is exactly what intuition does. For example:
MakeScreen is a multitasking/protected for of MakeVPort. MakeScreen
manages multiple tasks requiring MakeVPorts and preventing them
from tromping on each other. When an application needs to double buffer
it calles MakeScreen/RethinkDisplay. When the user is moving Screens
up and down intuition is also calling MakeScreen/RethinkDisplay.
These operations must be done in a safe interleaved manner since
these operations recreate lists, allocate memory etc.  Thats what
intuition provides.
The caution does not apply to any of the rendering routines. AreaFill
Linedraw,etc. are all the exact same graphics calls.  EA could have
designed there programs to make use of intuition. But because intuition
provides a protective coating around display operations, they are
slower.  EA must have felt that the slow down was too much. So they
had to write there own user interface, and not use intuition.
Again I repeat, those graphics routines cautioned against use with
Intuition running are only the display routines that it uses directly.
And it provided safe interfaces to those routines.
Dale Luck
Amiga