Atari ST Knowhow Workshop 4

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Atari ST Knowhow Workshop 4 assembler and hardware

Type of Event:	Workshop
From:	2012/03/10 15:00
Till:	2012/03/10 18:00
Recurring:	no
Organizer:	syn2cat
Cost:	0 EUR0 $ 0 £ 0 CHF
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Website:	http://wiki.hackerspace.l...
Attendees:	Sid, Kwisatz Log-in to RSVP
Contact Person(s):	Gunstick (mail)
Keywords:	atari st demo oldschool programming
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Where:	Hackerspace, Strassen (11, rue du Cimetière, L-8018 Strassen, Luxembourg)
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Getting into the detail to make the hardware do what you want

Have your emulator with assembler setup ready!

Howto:

download hatari. It is usually in the linux repositories, but you can also get the newest release at http://hatari.tuxfamily.org/download.html
download TOS. Hatari ships with emuTOS which should be ok, but a real TOS you can find via google http://bit.ly/waBToz
download turboass and devpac
Copy programming examples of workshop2 (share on lusitania) and workshop3 (git)

Copy all that into a folder, that will be your Atari root filesystem C:
start hatari, if you don't want emuTOS, press F12 -> ROM and browse to your downloaded TOS. Back to main menu -> Reset -> OK
to assign the Atari root harddisk folder: F12 -> hard disks -> Gemdos drive browse & [x] Boot from HD
change ST to medium rez: Options -> set preferences(voreinstellungen)... -> Medium(Mittel) -> OK
double clik on C, now you should see the turboass and devpac you have put in that directory. Try to start them
load any source. Assemble: includes may be in the wrong place, adapt the path.
Character issues: sometimes (e.g. swiss french keyboard) you cant type a \ : F12->keyboard -> [x] Scancode
for bigger projects like paradist you need more ram: F12 -> Memory -> 2MiB

programming the 68000 in assembler (using turboass or devpac)
- instructions
- the ULM intro code to get quickly started
specificity of the Atari ST hardware (workshop 1, from the programmer's view)
- where's my screen memory
- memory mapped hardware
smooth scrolling howto (recall workshop 2?)
- word and byte scrollers
- bit scroller
- be creative
color cycling effects (workshop 2 again)
- need some drawing skills
- more than 16 colors
tricking the ST hardware in other ways (as seen in workshop 3)
- the mystery of digital sound output
- other trickery by writing directly to hardware

These will be useful for today but also for future workshops. If you want to craft your own demo you will need grafics and sound in it.

To convert the GIF into degas format use ppmtopi1 from the linux netpbm tools (or XnView on windows

Other grafics you can draw on your own or convert from existing sources. Then reduce them to 16 colors (except if creating more advanced demos) and then convert them to degas format as above.
Music is usually a little routine you call 50 times a second. You can get those from the Sndh archive. Those tunes can be directly played by several music players. Most tunes are packed with the ICE packer, which is complicating things to use in assembler. Easiest is to unpack them first. Or just use the tunes which are not packed :-) How to play: soon.