Stable technology

[Phantom Hoover]

Other than easy construction and asynchrony, what advantages does it offer over p30 and p46 technology? p30 90° reflectors can fit in a 9x23 bounding box and can receive another glider in 30 generations; the stable 90° reflector in Gemini has an 81x70 bounding box and takes 488 generations to recover, so building complex circuits with p30 technology has an obvious advantage.

[calcyman]

... and takes 488 generations to recover ...

497 generations, actually. The smallest, fastest 180° reflector takes a mere 106 generations to recover, and Herschel-based circuitry is faster still.

what advantages does it offer over p30 and p46 technology?

• Easier to synthesise and destroy with gliders
• Reflectors are more versatile, thanks to Herschel tracks
• Completely asynchronous, therefore easier to design
• Can emit gliders at any time, as opposed to multiples of 30 generations
• Runs faster in HashLife

If you're still not convinced, try and construct either Gemini or my Phi calculator using only p30 technology.

[Phantom Hoover]

But the Universal Turing Machine was implemented with p30, so it's certainly practical for computation.

[calcyman]

But the Universal Turing Machine was implemented with p30, so it's certainly practical for computation.

The Universal Turing Machine is not universal; it has a finite tape. The only infinite tapes implemented so far use stable technology.

[igblan]

The only infinite tapes implemented so far use stable technology.

Not true. The original MRM was implemented using P30 technology, based on Dean Hickerson's Sliding Block Memory. It's all I knew at the time.

Cheers, Paul

[calcyman]

Not true. The original MRM was implemented using P30 technology, based on Dean Hickerson's Sliding Block Memory. It's all I knew at the time.

But are they not registers, rather than tapes? They store data in O(e^n) space, rather than O(n) space.

[igblan]

I might admit to the charge that the MRM is not "practical", but nevertheless it is a UC implemented in P30.

Cheers, Paul

[calcyman]

but nevertheless it is a UC implemented in P30.

Yes, it is a Universal Computer. Or rather, it would be if it weren't for a glitch at (1330,6620).