From: csg019@cch.coventry.ac.uk (-~=Zaphod=~-)
Subject: Re: New hardware reference guide?
Organization: Coventry University
Date: Thu, 19 Nov 1992 12:46:40 GMT

In article <1992Nov18.180612.15191@ultb.isc.rit.edu> eas3714@ultb.isc.rit.edu (E.A. Story) writes:

>Other considerations... Does the machine have $C0 Fast ram?  Or is it
>$20? Or perhaps it doesn't have FAST ram in the original 24-bit address
>space at all. (A3000, A4000).  The OS thinks about all these things, do
>demo (or for that matter, game) programmers?

No i doubt it, most games/demos are run directly from the boot block to save
memory, and as you will be aware, the A500 is still regarded as the base 
machine, so most code code in chip RAM anyway. Any fast ram could still be
allocated in the boot block, which would tell the program where to load.
Ala "Speedball" bootblock.

>>>b)crashes with a new OS version or when started from system that is 
>>>  booted further than the initial CLI.
>>It would not crash under new OS versions, because it would only use a few
>>bare essential routines like Forbid() and Permit().
>
>Most just hit INTENA and DMACON, anyway.

After task switching has been disabled, theres nothing to worry about.
Just turn the mutitasking off, strut your funky stuff, then turn it back on
again, with no side effects, thats how i do it.

>>>c) does generate bogus displays on either NTSC or PAL systems.
>>Depends what you mean by bogus displays.
>>NTSC users would loose a portion of the screen due to the fact that the
>>NTSC screen can't display as many lines at a PAL screen.
>
>Well, I know what *I* mean by bogus displays.  How about one that
>doesn't work at all...  And it's easy to fix... I think 90% of these
>"demo" programmers are guilty of it too.  How 'bout waiting on a
>scanline that doesn't exist?  I can't tell you how many of these "PAL
>only" programs work on an NTSC machine by changing just one byte in a
>test on DFF004/6 or in a copper list that generates an interrupt.  It's
>absolutely ridiculous.  I can live with lossing a portion of my
>display.. its gotta happen, but when it doesn't work at ALL, thats
>stupidity.

Agreed, but we all have a scan line zero don't we?
As for testing $dff006, i used to do that :) until i found out about the
blitter interupts.
I can't see why people give demo writters such a tough time. If the demo does
not work on your machine, then just delete it. You don't pay for them, so its
no major loss. If a game does not wotk, then thats a different matter.

>>1.. Write another version where the graphics are kept withing a smaller
>>area on the screen.
>
>Ya, but of course, most of these programmers are too lazy to do so....
>otherwise "PAL only" wouldn't be so popular a phrase.

Europe is *the* demo writting scene, most demo writters come from Europe so
write demos to impress other European groups.
I've never seen an NTSC demo (apart from them boring ray-traced animations,
that take zero amount of programming ability).

>>2.. Write a just an NTSC version, so all the lucky PAL owners have a chunk
>>of screen missing (*not big OR clever CINEMAWARE*).
>
>Or just center the NTSC size screen on a PAL display.  

How about using vertical size on your monitor to get an NTSC version of a
PAL game/demo then?

> 
>>>d) risks hardware damage with things connected to the serial or parallel port.
>>How could it *dammage* hardware?

>I can't wait for the first complaint from a A4000 or A1200 owner when
>one of these demos hits the wrong register and the display goes to 31Khz
>on their 1084... You don't think THAT could damage hardware?  

Why would anyone hit the wrong register?
No one just sits there and says "I know i'm gonna hit register $dffxxx for a 
laugh, even though its not in the manual."

>The point is that the serial and parallel ports shouldn't even be
>active, yet I've seen my modem lights flash during demos... most
>annoying.

It could be quite a good idea if you got them to flash in time to the music!

 ;)
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