Team 4Project 1 Presentation

Mapping Parallel Ports to LPT’s & USB Host Controller Interfaces

Tom, Jen, Curtis, Ashley, Scott

Mapping Parallel Ports to LPTs

What is a LPT port?

LPT (Line Print Terminal) is the common parallel port interface on a computer that connects the printer to the computer.

More commonly used in legacy systems

Mapping

Select Printer Type

Types of Parallel Ports

Unidirectional – Computer sends data to printer

Bidirectional- Printer and computer communicate

Enhanced Parallel Port (EPP)- Like bidirectional but with increased performance

Extended Capabilities- Came out shortly after EPP. Includes data compression for better throughput

IEEE 1284- Ensured compatibility and optimum performance with almost any parallel peripheral

USB Host Controller Interfaces

USB Host Control Interfaces

One of the original intentions of USB was to reduce the amount of cabling at the back of your PC.

USB uses tiered star topology like 10BaseT Ethernet, requires a hub, adds expense, cables, and boxes, but now devices have built-in hubs like keyboards & monitors

Benefits: monitored power to each device, both high and low speed devices can be supported, up to 127 devices can be connected on one USB bus with the ability to add more port/host.

USB Host Control Interfaces

USB 1.1 - 2 host controller interface specifications - UHCI (Universal Host Controller Interface) burden on software companies & Open Host Controller Interface (OHCI) which puts burden on hardware.

USB 2.0 - EHCI (Enhanced Host Controller Interface) one interface standard means 1 driver

USB uses 4 shielded wires - 2 for power, 2 are a twisted pair, it uses NRZI (Non Return to Zero Invert)

USB Host Control Interfaces

Dynamically loadable and unloadable drivers - uses Product ID/Vendor ID combinations to load appropriate driver, fee for VID, but standards organization provide extra VID for non-commercial

USB supports control, interrupt, bulk and isochronous transfers.

Questions?