What is Tetris lag?

[myndzi]

I really wish this community had a way to recognize or reward helpful, well thought out answers.

This is a good idea, and I've seen it before (thanks button), but I'll have to say I'm not interested in implementing it in this code base...

[Hornswoggler]

What about display lag? Anybody find LCD more laggy than CRT??

[myndzi]

I didn't actually cover that one, but you may as well start talking about gold plated connections and stuff if you're gonna go into all the hardware sources. Some LCDs can add a couple frames over a CRT, some can be configured to not do the post-processing that adds those frames, and some there's no help for it. I don't know how the best LCD stacks up against the best CRT, but the general preference to my knowledge is for CRTs, though it might not matter much to you unless you're hardcore into TGM.

[Lucho]

I read around here that ps/2 connected keyboards cause less input lag than usb ones, I use a usb keyboard and I dont notice lag, maybe on sub 30 speeds is noticeable

[XaeL]

Ps/2 uses interrupts.
USB uses polling.

USB @ 1000hz is still slower than interrupts due to the fact that keyboard interrupts take less than 1ms to notify the relevant hardware controller.

[zaphod77]

There are three main types of tetris lag.

1) Slight lag in response of beyboard or display. This really only matters when playing TAP or TI, as the play speed of them gets very fast, and those few milliseconds can mean the difference between a premature lock and a success.

2) The game responding horribly. This is known to happen a lot on tetris friends.

3) THe period when you are adjusting from one tetris games' control to another games very different control.  Common causes of this type of tetlag are switching to and from flat side down orientation, changing from step reset to move reset and back, switching from hard drop to sonic drop and back, and switching from bottom based to center based rotation systems.  Nearly all of these are triggered when switching between TGM games and modern Guideline games.

[myndzi]

Ps/2 uses interrupts.
USB uses polling.

USB @ 1000hz is still slower than interrupts due to the fact that keyboard interrupts take less than 1ms to notify the relevant hardware controller.

This is true as  far as it goes, but 1000 polls a second is a bit overkill when the game only cares about every 1/60th of a second...

In short, you're not likely to notice or care - but if it makes you feel better PS/2 is technically advantageous, probably.

Note: interrupts may take priority on the system bus but that doesn't mean that they aren't queued up as usual in the O/S to be dealt with the same way...

[XaeL]

Note: interrupts may take priority on the system bus but that doesn't mean that they aren't queued up as usual in the O/S to be dealt with the same way...

Agreed but still, in general interrupts > polling (dependant on overheads of interrupts BLAH BLAH)