From: neil@cs.hw.ac.uk (Neil Forsyth)
Newsgroups: comp.sys.atari.st
Subject: Re: TT Compatability questions
Keywords: TT, ST, compatible, games, applications
Date: 7 Sep 92 09:05:00 GMT
Organization: Dept of Computing & Electrical Engineering, Heriot-Watt University, Scotland

In article <H.2jCeQ8EYz7o@fredrik.atari.no> jornmoe@fredrik.atari.no writes:
>In <1992Sep3.115337.3528@cs.hw.ac.uk>, Neil Forsyth writes:
>>>No, not many games do work (at least without doing some tricks)! But
>>>does it matter. Who buys a TT for playing games? I'd rather buy a LYNX
>>>for that purpose:-)
>>
>>It matters plenty! If games don't work on the TT because they are poorly
>>written and don't take account of the 68030 then the same games will not
>>work on the Falcon. I can easily imagine people buying Falcons to play
>>games.
>>
>
>If You'r concerned about Falcon's compatibility you'r doing some wrong 
>assumptions!

Really?

>The TT and the Falcon 030 may have the same processor, but that's not the 
>same as beeing identical machines in respect to compatibility with the ST.
>
>First, all hardware in the Falcon resides within the same 24Bit addressing 
>range as th ST. In the TT, there are a full 32Bit addressing range wich
>causes a lot of trouble for some games.

The hardware addresses in the ST, TT and Falcon are the same (additional
features being an exception). The MMU is programmed to map $FFxxxxxx to
$00xxxxxx so there is no problem.
My 'game code' works on all machines why can't others?

>Second, the Falcon is designed to be as compatible with the ST as possible.
>The TT was designed to be as powerfull as possible, and at the same time
>a TOS machine wich should run any well written GEM application. Nothing
>more was ever promised.

If a programmer sticks to Atari's developer guidelines then *ALL* Atari
680x0 machines are compatible.

>Third, the falcon is a consumer product, the TT is not! This beeing a fact 
>makes it obvious why Falcon has to be more 'old-ST-games' compatible than
>the TT was.

I view the TT as being to the ST what 486DX-33 PC's are to 386SX-16 PC's.
They are every bit as commercial. If you buy a PC game these days you can bet
it will work on any PC. This should be true of ST games on the Falcon.

>And last, don't you forget that many games doesn't even tolerate the 16Mhz
>and cache of the MSTE (or speedup-boards for old ST(E)'s). Some games are
>even quite intolerant to different TOS versions to! So, I'd bee more concerned
>about the compatibility of the games, rather than about the compatibility of 
>the machines!

Most of the games that don't work with faster processors and caches are
written by f*ckwits that go straight for the DMA/FDC hardware directly. This
is because their software timing loops get shortened. Why didn't they use
the BIOS or even XBIOS calls?
Atari are now recommending that Falcon (and I guess ST) games work on hard
disk and use copy protection based on word entry from a manual.

To sum up, I have tried running a *LOT* of ST games on a Falcon and less than
10% of them worked. This is one reason I think the Falcon will fail if markted
as a games machine. The available leisure software will be small.
Only a couple of the games worked after disabling the cache and setting
the speed to 8Mz. Since most games that load from a bootsector and don't use
system calls failed I assume that they were not 68030 compatible.
Atari were not to blame for these incompatibilities however I do blame them
for not kicking butt when the TT didn't run software. Programmers should have
learned their lesson back then.

+----------------------------------------------------------------------------+
! DISCLAIMER:Unless otherwise stated, the above comments are entirely my own !
!                                                                            !
! Neil Forsyth                                                               !
! Department of Computing and Electrical Engineering                         !
! Heriot-Watt University                                                     !
! Edinburgh, Scotland                                                        !
! United Kingdom            Email: neil@uk.ac.hw.cs, ..!ukc!cs.hw.ac.uk!neil !
!                                                                            !
! "'Have you got any?' he asked, expecting the answer no" - Monty Python     !
+----------------------------------------------------------------------------+