Speedup POKEs

[StanVanman]

When someone posted some amazing "turbo" versions of Renegade last week I was fascinated as to how it had been achieved, and apparently it's just a bizarre quirk of the Speccy that there are games you can speed up by 200-300% with a single POKE. A kind user sent me some other examples:

Match point - poke 53646,0/53657,0
Maziacs - poke 42059,201
Target Renegade - poke 62769,0
RoboCop - poke 34039,0
Fast Food - 26008,62
Kung Fu Master - Poke 37356,0
Gunstar - poke 44436,201
Green Beret - poke 41998,201
Phantom Club - poke 60930,201
Movie - poke 62066,201
Kinetik - poke 53151,201

Try the Maziacs one to see how dramatic the effect can be - it's actually bordering on unplayable. But it turns Fast Food into Actually Fast Food, a huge improvement.

But nobody seems to talk about this anywhere. These POKEs don't appear on sites like The Tipshop, and as far as I can tell there's no list anywhere of games which have already been modded in this way, or might be susceptible to this "hack". How can we find out? Anyone got any info?

[WhatHoSnorkers]

So out of interest I looked at the Maziacs one. That's a little delay routine. He PUSHes BC to the stack, loads BC with 100, pushes BC to the stack AGAIN, then puts 0 into BC, and does a DJNZ, then POP BC, DJNZ, POP BC, Return.

A delay loop. POKEing replaces the first instruction with RETurn so you don't delay, hence the speed boost.

With machine code programs, your problem is usually "it's too fast" not "it's too slow" so there will be loads of these.

Hard to algorithmise, but DJNZ instructions are probably what to look for as a simple loop.

[sn3j]

Maziacs: If I remember it right the speed gets faster with every level. So there's a reason for the delay loop.

[Bedazzle]

Lode runner faster level draw poke file.
Must work for both 48/128 versions.

[dpt]

The Great Escape has a delay loop you can disable: POKE 41109,201

See https://dpt.github.io/The-Great-Escape/asm/A095.html

It only affects indoor scenes though.