The most important feature of the parallel port of your PC is its mode. Possible modes are SPP, PS/2, EPP and ECP.
On 286, 386 and older 486 machines, the parallel port is on a separate card (e.g. I/O card, parallel port card, Hercules video card with a built-in parallel port) and it is SPP or PS/2. If it isn't then you might find jumpers on the card to set the mode. Refer to the documentation of your card for more details.
On newer 486 and all Pentium (and above) machines, the parallel port is integrated onto the motherboard and you can set its mode in the BIOS setup. The usual aliases for the SPP mode are "Compatible", "Normal" or "Standard". "BPP" and "Extended" usually stands for the PS/2 mode and "Enhanced" for either the EPP or the ECP mode.
However, on most Pentium and above motherboards, setting the parallel port to SPP mode won't give you a true SPP port because of the slight changes in the electronical layout of the parallel port. More on this below.
Don't rely on what port mode your BIOS setup shows. Rather check the real mode of your parallel port with LPTDetect.
SPP mode means bidirectional control lines and unidirectional data lines. The X1541 cable makes use of the bidirectional control lines. PS/2 differs from SPP in that it has bidirectional data lines. EPP and ECP offers several enhanced features, that PC programs can make use of, but the control lines are not bidirectional anymore in these modes. More on this below.
