#define port_base 0x378
#define port_status port_base + 1
#define port_control port_base + 2

hello there, i cant understand the last two line - port_status port_control.....can any one give some clear idea or show me the
way(site address) from where i can take help.

thanks.

There is lots of information that can be found by googling on how a parallel port works.

If you look at a description of the original PC parallel port there are 17 I/O lines that are accessed/controlled via three 8 bit ports. The arrows show if they are inputs or outputs referenced to the computer. The second link shows the signal timing and basically how communications works.

Base port - Data bits 0-7

Status port - Input pins i.e. signals coming from the printer like paper out and printer busy

Control port - output pins i.e. strobe, autofeed.

http://www.lammertbies.nl/comm/cable/parallel.html
http://www.interfacebus.com/Design_C...l_PC_Port.html