Appendix D: X65 Compared to Classic 8-bit Systems¶
Introduction¶
This chapter provides detailed comparisons between the X65 microcomputer and several classic 8-bit systems, highlighting similarities, differences, and advantages. These comparisons can help developers familiar with vintage platforms understand how their knowledge transfers to the X65 environment.
CPU Comparison¶
Feature |
X65 (65C816) |
Commodore 64 (6510) |
Apple IIe (65C02) |
Atari 800XL (6502) |
SNES (5A22/65C816) |
|---|---|---|---|---|---|
Word Size |
8/16-bit |
8-bit |
8-bit |
8-bit |
8/16-bit |
Address Space |
16MB |
64KB |
64KB |
64KB |
24-bit address bus |
Clock Speed |
~7MHz |
~1MHz |
1MHz |
1.79MHz |
3.58MHz |
Direct Page |
Relocatable |
Fixed Zero Page |
Fixed Zero Page |
Fixed Zero Page |
Relocatable |
Index Registers |
8/16-bit X, Y |
8-bit X, Y |
8-bit X, Y |
8-bit X, Y |
8/16-bit X, Y |
CPU Modes |
Native Mode |
N/A |
N/A |
N/A |
Emulation/Native |
Stack Size |
64KB |
256 bytes |
256 bytes |
256 bytes |
64KB |
Special Instructions |
WAI, Block move (MVN/MVP) |
None |
WAI, STP, BBR, etc. |
None |
Block move (MVN/MVP) |
Memory Architecture¶
Feature |
X65 |
Commodore 64 |
Apple IIe |
Atari 800XL |
SNES |
|---|---|---|---|---|---|
Total RAM |
16MB |
64KB |
64KB + 128KB aux |
64KB |
128KB |
ROM |
None (Loaded from SD) |
20KB |
16KB |
24KB |
Game cartridge |
Memory Model |
Flat, Linear |
Banked |
Paged |
Cartridge + RAM |
Banked |
I/O Method |
Memory-mapped |
Memory-mapped |
Memory-mapped |
Memory-mapped |
Memory-mapped |
Banking System |
256 banks of 64KB |
ROM/RAM/IO banking |
Soft switches |
ANTIC/GTIA/PIA |
Various controllers |
Special Areas |
Direct Page (relocatable) |
Zero Page (fixed) |
Zero Page (fixed) |
Zero Page (fixed) |
Direct Page (relocatable) |
Graphics Capabilities¶
Feature |
X65 (CGIA) |
C64 (VIC-II) |
Apple IIe |
Atari 800XL (ANTIC/GTIA) |
SNES (PPU) |
|---|---|---|---|---|---|
Resolution |
Up to 768×240 (×480 interlace) |
320×200, 160×200 |
280×192, 560×192 |
320×192, 80×192 (ANTIC modes) |
Up to 512×478 |
Colors |
256 colors |
16 colors |
16 colors (Lo-Res), 6 colors (Hi-Res) |
256 colors (GTIA modes) |
32,768 colors (256 on-screen) |
Sprites |
8 sprites (up to 64px width) with multiplexing |
8 sprites (24×21) |
Software only |
4 missiles, 4 players |
128 sprites (32×32) |
Text Modes |
48×30, 96×30 characters |
40×25 characters |
40×24, 80×24 characters |
Multiple ANTIC modes |
32×28 characters |
Special Effects |
HAM mode, MODE7, Raster/DL interrupts |
Raster interrupts, FLI |
Double hi-res |
Display list, GTIA modes |
Mode 7, scaling, rotation |
Rendering System |
Display list |
Raster-based |
Memory-mapped |
Display list |
Tile-based + sprites |
Graphics Memory |
Any two banks of 16MB RAM available |
Fixed VIC layout |
Fixed memory pages |
ANTIC memory map |
VRAM with DMA |
Sound and Audio¶
Feature |
X65 |
Commodore 64 |
Apple IIe |
Atari 800XL |
SNES |
|---|---|---|---|---|---|
Primary Sound |
Yamaha SD-1 FM |
SID |
Speaker |
POKEY |
SPC700 |
Channels |
16 FM channels + EQ |
3 voices + filters |
1 speaker |
4 channels |
8 channels |
Secondary Sound |
2 PWM channels |
- |
Mockingboard (optional) |
- |
- |
Sound Synthesis |
FM, 4-operator |
Subtractive, 3 oscillators |
Square wave |
Filtered digital |
ADPCM samples |
Volume Control |
Per-channel + master, Mixer |
Per-channel + master |
Single level |
Per-channel |
Per-channel + master |
Effects |
Built-in EQ, vibrato |
Filters, ring mod |
None built-in |
Distortion |
Echo, reverb, FIR filter |
Note Range |
Full MIDI range |
8 octaves |
Limited |
3.5 octaves |
Full MIDI range |
Input/Output Capabilities¶
Feature |
X65 |
Commodore 64 |
Apple IIe |
Atari 800XL |
SNES |
|---|---|---|---|---|---|
Keyboard |
USB, Built-in |
Built-in |
Built-in |
Built-in |
Controllers only |
Joystick |
2 DE-9 ports |
2 DE-9 ports |
16-pin ports |
2 DE-9 ports |
2 controller ports |
Storage |
USB Pen Drive |
Datasette, Disk Drive |
Disk Drive |
Cassette, Disk Drive |
Game Pak |
Serial |
USB-UART |
Serial IEC |
Serial |
SIO |
- |
Networking |
Wi-Fi, Bluetooth |
Cartridges/adapters |
Optional cards |
- |
- |
Expansion |
CPU bus expansion |
Cartridge/Expansion port |
Expansion slots |
Cartridge port, ECI |
- |
Video Output |
DVI-D |
Composite/RF |
Composite |
Composite/RF |
Composite/RGB |
Audio Output |
Stereo RCA |
Mono |
Built-in speaker |
Mono |
Stereo |
Programming Environment¶
Feature |
X65 |
Commodore 64 |
Apple IIe |
Atari 800XL |
SNES |
|---|---|---|---|---|---|
Native Language |
65816 Assembly |
6510 Assembly |
6502 Assembly |
6502 Assembly |
65816 Assembly |
High-level |
NeoBASIC, C |
BASIC |
BASIC, Pascal |
BASIC |
C |
Development Tools |
Modern assemblers, emulator |
BASIC, ML monitors |
BASIC, monitors |
BASIC, Assembler Editor |
Custom dev kits |
Debugging |
Monitor, emulator tools |
Machine language monitor |
Monitor program |
DEBUG cartridge |
Special hardware |
Cross-development |
Full modern toolchain |
Modern cross-dev tools |
Modern cross-dev tools |
Modern cross-dev tools |
Emulators, assemblers |
Community Resources |
GitHub, Discord |
Massive legacy + active |
Active community |
Active community |
ROM hacking community |