MBR Boot Manager

We want this:

The entire boot manager program is in the MBR.

The program boots active partition with standard error messages if no key is pressed.

If right Alt is pressed during boot a prompt is printed to the screen.

If 1, 2, 3, or 4 is then pressed, that partition entry is set active, and the entry is booted.

If Esc is pressed in stead the active partition is booted.

If a, b, c, or d is pressed in stead entry no. 1, 2, 3, or 4 is set active, and that partition booted, but a mark is set that at next boot the previous active mark should be  restored.

If a number or letter is pressed, but that partition is not present nothing should be done.

The first version is present. It did not become so advanced, but it works.

SHA1 D0C6339BFF70F80A84912DD481016495B58271E9, 408 bytes.

If right Alt is pressed during boot a prompt "#" is printed to the screen.

If 1, 2, 3, or 4 is then pressed that partition entry is set active, and the entry is booted.

If there is no matching entry or another key is pressed nothing happens.

Intel CPU fan

Will the Intel Core i5-3570 CPU fan run if it is just connected by the yellow and black wires to 12 V?

Yes, the fan will run at full speed.

Will the fan run if the same wires are connected to 7 V? Yes.

To 5 V? Yes.

What about the Intel Core i7-4790 fan? Model Number: E97378-001.

The fan runs at 12 V. At 7 V it moves a little, but does not run. At 5 V it does not move at all.

At about 1000 RPM it makes a clicking noise here. And it makes at pretty loud noise when starting.