Hallo Christian,

your posts confuse me a bit. In first post you wrote:

hello everybody i will implement a 3 state buffer like 74LS244 for more current in the 8051... but i forgot something very simple. i have been looking for it in google but couldn't find it

what is the logic output when the input is floating? is it a 0 or 1?

Here you ask for the performance of 74LS244, if the INPUT is floating.

In the last post you wrote:

i forgot to mention that i'm using 74ls244 because i have it. but it is always nice to learn something new. so i will now look for a simple buffer not a 3state buffer.

A TRISTATE buffer has something to do with OUTPUTS. So, both questions together make no sense to me.

If you use a buffer, then you have an input and an output. The input must never float, and the output can be made floating, if you want this. If you do not want to use this tristate feature (outputs are made to float), then just let the according enable inputs inactive.

Port lines can sometimes go into tristate mode. Please have a look at bible links, Erik is sooooo often remembering here, to find out when this will happen. Standardly, an input of a logic gate should never float, because otherwise the output would be undefined and could even oscillate, as Andy stated. If you cannot be sure, that the output, which is driving your input of buffer, is always either low or high, means if it can be undefined or floating for some time, you should add a simple pull-up of about 4.7k...10kOhm per input. With 74LS-family there's already an active pull-up integrated, but it's not good design practice to trust alone on this internal circuitry. It would be better to add an extra pull-up, as I told above.
If you use 74HCMOS parts, there's no internal pull-up. Here an external pull-up of 4.7k...10kOhm per input is needed. You can use very tiny single-in-line resistor array for this purpose.

So, again. Whether you use a standard logic gate, a buffer, a buffer with tristate, etc. their inputs must never float or be undefined for longer periods. Eventually external pull-ups are needed.

Now, to the different types of buffers:

74LS244 has uncomfortable pin out. Also, power dissipation is high. It's better to use 74HCMOS buffers, for instance 74HC541. It can sink or source up to 35mA per output and 70mA totally, all 8 outputs together. So, if all outputs simultaneously source or sink current, 8.75mA per output is possible.

Hope this helps,
Kai