Microchip Technology MPLAB ICE, User Manual

Page: 82 / 192

MPLAB
®
ICE User’s Guide
DS51159B-page 82

2001 Microchip Technology Inc.
4.4 Configuring the LPT Port
To display information about the PC’s parallel ports, select
Options>Development Mode. The Ports tab of this dialog displays
information about the available LPT ports on the host PC. Select an available
LPT port from the dropdown list. To determine how this LPT port is configured
on your system, click Query Port Info (Figure 4.2).
Figure 4.2: Development Mode Dialog – Ports Tab
Depending on your PC motherboard and add-ons, there may be up to four
different types of parallel ports:
• SPP
• PS/2
• EPP
• ECP
The SPP port was the original parallel port. It was designed for sending 8-bit
wide data, but it was not designed for receiving data. Data can be received on
this type of port by using the status signals, but it can only be done four bits at
a time. This mode of operation is called Compatibility Mode.
The PS/2, EPP, and ECP type parallel ports can communicate in a bi-
directional mode. That is, they can both send and receive 8-bit wide data.
Most newer PC’s contain either a bi-directional port or a port that can be
configured to either a bi-directional or compatibility mode port.