Wiring skills: Parallel direct connections (1)

Parallel direct connection is the second solution for data transmission between computers. Due to the need to connect more wires, the required cables will be a little complicated, but given its speed, the time and effort we spend on cables is worthwhile.

Most people know that parallel linear cables are "Laplink" cables. When you purchase the Laplink program or PCAnywhere, a parallel direct connection cable is provided. It is usually yellow. After reading this article, you will be able to create a parallel direct connection cable by yourself.

Parallel (LPT) ports have different types, specifically four, but we use the same network cable to use them. We will discuss them one by one to gain a comprehensive understanding of them.

Currently, in terms of speed, a standard LPT port can reach a speed of about 40 to 60 Kbps, while a faster LPT port can expect a speed close to 1 Mbps. In any case, this is a significant improvement over the serial cable (zero modem cable.

Let's take a quick look at the data transmission method on the parallel link, which will help us understand why this method is much faster than the serial mode:

This figure shows a parallel transmission. In serial transmission, a data block is transmitted at a time, while in parallel, in this example, four data blocks are transmitted at a time. Because the parallel port transmits data on multiple wires at the same time, it is faster than serial.

If you think it is a bit difficult to understand, consider the parallel cable as a four-lane expressway that can drive four vehicles at the same time, the serial cable is a single-lane expressway that only runs one car at a time. I hope this explanation will be helpful to you.

Parallel Port (LPT)

Displays the parallel port of a new computer, that is, the LPT port.

On the new computer, you will find that the LPT port is always on the top of the two COM ports, and it is usually purple. No matter what type of LPT you use, they all look the same, but the electronic features of the four different types of LPT ports will be different, and this feature is transparent to users. All LPT ports are negative DB-25 connectors. Various LPT ports

Before analyzing the pin distribution of LPT ports, let's take a look at the different types of existing LPT ports. Similarly, because it is on the LPT port, you can get different speeds: