If cloning an 8-bit computer in FPGA, one might as well clone the best one around.

I feel that the Atari 6502 series are the best, for the following reasons.

• Full-custom ASICs designed and built for the job.
• Sprites and collision detection
• Fewer socket contacts to go faulty
• Huge software base
• Accurate video timing
• Versatile video controller

The big hurdle in cloning these machines is that many things have to be up and running at the same time for the software to work. The video, the sound, the keyboard and so on.

So I decided to clone the much simpler Acorn Atom, but fix the many defects of the 6847 chip by basing the video timings on the Atari machines. I did so, and added extra features such as

• Programmable character set, and lower-case text.
• Cross-hairs (in hardware)
• PS/2 keyboard and mouse interface
• USB serial interface
• Sprites
• Colour
• Palette
• Video and audio DACs
• POKEY and AY-3-8910 sound

In 2001, I started by toggling an LED on a development board. By 2005 I had cloned the Acorn Atom and had run out ideas for ways to improve it. Analogue TV started to go extinct and I was working 12 hour days to buy a home. I'd learned VHDL to my satisfaction and didn't really need an Atari clone.