HP Dc7700 HP Compaq dx7300 and dc7700 Business PC Technical Reference Guide, 1 - Page 91

Input/Output Interfaces Parallel Interface Control The BIOS function INT 17 provides simplified control of the parallel interface. Basic functions such as initialization, character printing, and printer status are provide by subfunctions of INT 17. The parallel interface is controllable by software through a set of I/O mapped registers. The number and type of registers available depends on the mode used (SPP, EPP, or ECP). Table 5-11 lists the parallel registers and associated functions based on mode. Table 5-11. Parallel Interface Control Registers I/O Address Register SPP Mode Ports EPP Mode Ports Base Data Base + 1h Printer Status Base + 2h Control Base + 3h Address Base + 4h Data Port 0 Base + 5h Data Port 1 Base + 6h Data Port 2 Base + 7h Data Port 3 Base + 400h Parallel Data FIFO Base + 400h ECP Data FIFO Base + 400h Test FIFO Base + 400h Configuration Register A Base + 401h Configuration Register B Base + 402h Extended Control Register LPT1,2,3 LPT1,2,3 LPT1,2,3 ------------ LPT1,2 LPT1,2 LPT1,2 LPT1,2 LPT1,2 LPT1,2 LPT1,2 LPT1,2 ------- Base Address: LPT1 = 378h LPT2 = 278h LPT3 = 3BCh ECP Mode Ports LPT1,2,3 LPT1,2,3 LPT1,2,3 -----LPT1,2,3 LPT1,2,3 LPT1,2,3 LPT1,2,3 LPT1,2,3 LPT1,2,3 Technical Reference Guide www.hp.com 5-13