Difference between revisions of "6502"
From SizeCoding
| (2 intermediate revisions by 2 users not shown) | |||
| Line 15: | Line 15: | ||
=== Zero page === | === Zero page === | ||
When using the 6502 for sizecoding, you'll mostly be working from zeropage | When using the 6502 for sizecoding, you'll mostly be working from zeropage | ||
| + | |||
| + | == 6502 Based Platforms == | ||
| + | *'''[[Atari 8Bit]]''' - Atari 8-Bit Family (Atari XL/XE, etc.) | ||
| + | *'''[[Apple II]]''' - Apple II(e) | ||
| + | *'''[[Commodore 64]]''' - Commodore 64 | ||
| + | *'''[[BBC Micro]]''' - Acorn BBC Micro/Master/Electron. | ||
| + | *'''[[Atari Lynx]]''' - Atari Lynx Handheld | ||
| + | |||
| + | == Generic 6502 sinus table generator == | ||
| + | <syntaxhighlight lang=""> | ||
| + | ldx #0 | ||
| + | ldy #$3f | ||
| + | make_sine: | ||
| + | value_lo | ||
| + | lda #0 | ||
| + | clc | ||
| + | delta_lo | ||
| + | adc #0 | ||
| + | sta value_lo+1 | ||
| + | value_hi | ||
| + | lda #0 | ||
| + | delta_hi | ||
| + | adc #0 | ||
| + | sta value_hi+1 | ||
| + | |||
| + | sta sintab+$c0,x | ||
| + | sta sintab+$80,y | ||
| + | eor #$7f | ||
| + | sta sintab+$40,x | ||
| + | sta sintab+$00,y | ||
| + | |||
| + | lda delta_lo+1 | ||
| + | adc #8 | ||
| + | sta delta_lo+1 | ||
| + | bcc nothing | ||
| + | inc delta_hi+1 | ||
| + | nothing | ||
| + | inx | ||
| + | dey | ||
| + | bpl make_sine | ||
| + | </syntaxhighlight> | ||
=== General 6502 Resources === | === General 6502 Resources === | ||
| Line 23: | Line 64: | ||
* Easy 6502 code tester https://skilldrick.github.io/easy6502/ | * Easy 6502 code tester https://skilldrick.github.io/easy6502/ | ||
* Synthetic instructions https://wiki.nesdev.com/w/index.php/Synthetic_instructions#8-bit_rotate | * Synthetic instructions https://wiki.nesdev.com/w/index.php/Synthetic_instructions#8-bit_rotate | ||
| − | |||
| − | |||
| − | |||
| − | |||
| − | |||
| − | |||
| − | |||
Latest revision as of 13:55, 8 April 2024
Contents
Introduction
Wanting to start sizecoding on a 6502 platform in this day and age can be tough.
So here is a bit of help to get you started:
The 6502 processor
The 6502 processor can be seen as the 8-bit micro ARM chip. It has only has 3 registers (Accumulator, X and Y registers) and a handful of instructions to work with.
Adressing modes
To be added.
Zero page
When using the 6502 for sizecoding, you'll mostly be working from zeropage
6502 Based Platforms
- Atari 8Bit - Atari 8-Bit Family (Atari XL/XE, etc.)
- Apple II - Apple II(e)
- Commodore 64 - Commodore 64
- BBC Micro - Acorn BBC Micro/Master/Electron.
- Atari Lynx - Atari Lynx Handheld
Generic 6502 sinus table generator
ldx #0
ldy #$3f
make_sine:
value_lo
lda #0
clc
delta_lo
adc #0
sta value_lo+1
value_hi
lda #0
delta_hi
adc #0
sta value_hi+1
sta sintab+$c0,x
sta sintab+$80,y
eor #$7f
sta sintab+$40,x
sta sintab+$00,y
lda delta_lo+1
adc #8
sta delta_lo+1
bcc nothing
inc delta_hi+1
nothing
inx
dey
bpl make_sineGeneral 6502 Resources
- 6502.org http://www.6502.org/
- 6502 instruction reference http://www.6502.org/tutorials/6502opcodes.html
- 6502 books http://retro.hansotten.nl/6502-sbc/
- 6502 Assembler tutorial https://dwheeler.com/6502/oneelkruns/asm1step.html
- Easy 6502 code tester https://skilldrick.github.io/easy6502/
- Synthetic instructions https://wiki.nesdev.com/w/index.php/Synthetic_instructions#8-bit_rotate
