Specifications
Little Board/P5i Technical Manual
2–14
2.6.2 ROM-BIOS Installation of Parallel Ports
Normally, the BIOS assigns the name LPT1 to the primary parallel port, and LPT2 to the secondary
parallel port (if present), and so on. However, the BIOS scans the standard addresses for parallel ports
and if it only finds a secondary port, it assigns LPT1 to that one. Configure the parallel port for the
primary assignment shown in Table 2–1, unless you have added another parallel port that occupies the
primary parallel port’s I/O addresses. In that case, make the Little Board/P5i’s parallel port the secondary
port.
2.6.3 Interrupts
The parallel port can be configured to generate an interrupt request upon a variety of conditions,
depending on the mode the port is in. (These are described in Chapter 3.) In most applications, the
interrupt is not used. The standard parallel port interrupts are:
Primary port IRQ7
Secondary port IRQ5
The parallel port interrupt is selected using SETUP.
2.6.4 DMA Channels
In ECP enhancement mode, the parallel port can send and receive data under control of an on-board
DMA controller. DMA channels operate with a request/acknowledge hardware handshake protocol
between an internal DMA controller and the parallel port logic. On the Little Board/P5i, select the DMA
request (DRQ) and DMA acknowledge (DACK) assignments using jumpers. You can configure the
parallel port to use either DMA channel 1 or DMA channel 3. To select a DMA channel for the parallel
port, set jumpers W18 and W19 as shown in Figure 2–4:
Figure 2–4 Parallel Port DMA Selection (W18, W19)
If you will not be using DMA with the parallel port, leave the jumpers off. This makes the DMA
controls available to other peripherals installed on the expansion bus.
2.6.5 Parallel Port Connector (J15)
Connection to the parallel port is through connector J15. Table 2–10 gives this connector’s pinout and
signal definitions. You can use a flat ribbon cable between J15 and a female DB25 connector. The table
also gives the connections from the header pins to the DB25 connector. Table 2–11 gives manufacturer’s
part numbers for mating connectors.