Difference between revisions of "Motorola 68000"

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Note:  Assigment direction is source,dest instead of dest,source !!!
 
Note:  Assigment direction is source,dest instead of dest,source !!!
  
=== Registers ===
+
==== Registers ====
 
To be added.
 
To be added.
  
== Atari ST ==
+
==== Instructions timing ====
The Atari ST systems consists of the M68k system with custom hardware for graphics and sound.
+
The number of cycles for each instruction is different depending of processor model in M68K family.
 +
: http://oldwww.nvg.ntnu.no/amiga/MC680x0_Sections/mc68000timing.HTML
  
=== Setting up ===
+
== Motorola M68K Platforms ==
Setting up your development platform for the Atari ST systems is quite easy, first get the following tools:
+
*'''[[Atari ST]]''' - Atari ST Sizecoding information
 
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*'''[[Atari Jaguar]]''' - Atari Jaguar Sizecoding information
* Assembler: VASM - This assembler is able to assemble directly to a TOS image
+
*'''[[Commodore Amiga]]''' - Commodore Amiga Sizecoding information
* Emulator(s): -. Make sure to use the original TOS 1.62 Image for best compatibility.
 
 
 
=== Compiling to a TOS image ===
 
Vasm -Ftos source.s -o source.tos
 
 
 
=== Video diplay ===
 
The Atari ST has a linear 320x200x4bit address space, which each nibble representing a color index 0..F from the palette.
 
 
 
To be added soon.
 
 
 
==== Setting a palette ====
 
Here is some code that will help you setup a palette
 
 
 
<syntaxhighlight lang="">
 
pea palette(pc)
 
move.w #6,-(sp)
 
trap #14
 
 
 
; Palette data
 
palette:
 
dc.w $000,$100,$200,$311,$422,$533,$644,$755
 
dc.w $575,$464,$353,$242,$131,$020,$010,$000
 
</syntaxhighlight>
 
 
 
==== Getting something on screen ====
 
Here is a bit of code to get you started:
 
 
 
<syntaxhighlight lang="">
 
;-----------------------
 
; Line-A Initialization
 
;-----------------------
 
; After calling this function, data register D0 and address register A0 point to a table ; with the starting address of the Line A variables.
 
; Address register A1 points to a table with the starting addresses for the three system ; font headers,
 
; and address register A2 points to a table that specifies the starting addresses of the; 15 Line A opcodes. There's no parameter required for this function, so all you have
 
; to do is call the word opcode label that you specified for the $A000 (Initialize)
 
; function.
 
dc.w $A000
 
movem.l (a0),a1-a4 ; A3=INTIN, A4=PTSIN
 
 
 
;---------
 
; For X&Y
 
;---------
 
frameloop:
 
move.w #200-1,d7 ; y
 
yLoop:
 
move.w #320-1,d6 ; x
 
xLoop:
 
 
 
; Putpixel
 
put_pixel:
 
move.b d6,d0 ; d0=x
 
eor d7,d0 ; d0=x^y
 
lsr.b #2,d0 ; d0>>=4
 
and #42,d0 ; d0&42
 
 
move.w d0,(a3) ; a3=color(d0)
 
movem.w d6/d7,(a4) ; a4=x,y`
 
 
dc.w $A001 ; put pixel command
 
 
 
dbra d6,xLoop ; decrease and branch
 
    dbra d7,yLoop
 
 
 
; Wait loop
 
bra frameloop ; .s *
 
 
 
</syntaxhighlight>
 
 
 
=== Sound ===
 
The Atari ST systems use the YM8192 chip to generate sound.
 
To be added soon.
 
 
 
==== Make some noise ====
 
To be added soon.
 
 
 
=== Additional Resources ===
 
Sizecoding on the Atari ST is not very huge yet, so resources are sparse.
 
* Spkr's Github: to be added
 

Latest revision as of 10:43, 8 April 2022

Introduction

Wanting to start sizecoding on a Motorola 68k platform in this day and age can be tough.

So here is a bit of help to get you started:

The Motorola 68k processor

The Motorola 68k processor...

Note: Assigment direction is source,dest instead of dest,source !!!

Registers

To be added.

Instructions timing

The number of cycles for each instruction is different depending of processor model in M68K family.

http://oldwww.nvg.ntnu.no/amiga/MC680x0_Sections/mc68000timing.HTML

Motorola M68K Platforms