Parallel port output. For Spanish version click here. Copyright Tomi Engdahl 1. Index. PC parallel port can be very useful IO channel for connecting your. PC. The PCs parallel port can be used to perform some very amusing hardware interfacing experiments. The port is very easy to use when you first understand some basic tricks. This document tries to show those tricks in easy to understand way. WARNING PC parallel port can be damaged quite easily if you make mistakes. If the parallel port is integrated to the. Safest bet is to buy an inexpensive IO card which. If you manage. to damage the parallel port on that card, replacing it is easy and inexpensive. NOTE The IO port level controlling details here has proven to work well with parallel ports on the PC motherboard and expansion cards connected to ISA bus. The programming examples might not work with PCI bus based IO cards they can use different hardware andor IO addresses, their drivers make they just look like parallel ports to normal applications. The programming examples do not work with USB to parallel port adapters they use entirely different hardware, their drivers make them to look like normal parallel port to operating system normal applications. Every reasonable care has been taken in producing this information. Welcome to my tutorial on Serial Port Communication in VB. Net. Lately Ive seen a lot of questions on how to send and receive data through a serial port, so I thought. Main Menu Knowledgebase Serial COM Port Application. DoEvents Communication Methods Control. InvokeBeginInvoke Delegates Download Enumeration Event Driven. Serial Port C Example Windows Forms' title='Serial Port C Example Windows Forms' />However, the author can accept no responsibility for any effect that this. It is the responsibly of the end user to determine fitness. The circuits and software shown here are for non commercial use without. Chiropractic Report Of Findings Software Development there. PC parallel port is 2. D shaped female connector in the back of the. It is normally used for connecting computer to printer, but many. Not all 2. 5 are needed always. Usually you can easily do with only 8. I have presented those. Those output pins are adequate for many purposes. Pins 1. 8,1. 9,2. Serial Port C Example Windows Forms' title='Serial Port C Example Windows Forms' />Those datapins are TTL level output pins. This means that they. V when they are in low logic level 0 and 5. V when they. are in high logic level 1. In real world the voltages can be something. The output current capacity of the parallel port is limited to only. Here is a simple idea how you can connect load to a PC parallel port data pins. Dn Out. Sourcing Load up to 2. A 2. 4 v. Ground. This is not the only way to connect things to a parallel port. The parallel port data pins are TTL outputs, that can both. In ordinary parallel port implementations the data outputs are 7. LS3. 74 IC totem pole TTL outputs which can source 2. A and sink 2. 4 m. A. Regular TTL outputs basically consist of a two stacked transistor in series. This is called a totem pole output. At any given time one of these. To pull the output high. H, which sources positive. To pull the output low, only the lower. L conducts, sinking current to ground an external device. H on V. TTL output on 1 high, sourcing current. L off V. Gnd. 5. H off. V. TTL output off 0 low, sinking current. Gnd. The outputs are designed so that they give at least 2. V at 2. 6 m. A load. This 2. 6 m. A figure is for ordinary LS TLL circuits used, the LSI implementations used in many computers can give more or less. For example quite popular few years ago UM8. C1. 1 C parallel port chip can only source 2 m. A. Simple current sinking load connection. Dn Out. Sourcing Load up to 2. A 2. 4 v. Ground. When taking current from PC parallel port, keep the load low, only up to few milliamperes. Trying to toke too much current for example shorting pins to ground can fry the parallel port. I have not killed any parallel port yet in this method, but I have had in cases where too much load has made the parallel port IC very hot. Be careful. If you have an external 5 volt supply, you have another option. Data Out pins to sink up to 2. A from your 5 volt supply. This can be made with a circuit like this. Sinking Load up to 2. A 4. 2v. Power Supply. Dn Out. Ground Gnd. The load gets power then you have external 5. V on and the printer. This circuit gives you capability of. You need to be careful with this circuit, because with this. My advice is to be very careful with this type. V power supply gets. V though the load to printer port when. The most convient source external 5. V might. be from same other port on your PC USB, joystick, keyboardmouse etc. I have used mostly sinking type circuits and this article. Simple LED driving circuits. You can make simple circuit for driving a small led through PC. The only components needed are one LED and one. You simply connect the diode and resistor. The resistors is needed to limit the current taken. LEDs and is still safe value not overloading the parallel port. In practical case the output current will be few. LED, which will cause a typical LED. Then you connect the circuit to the parallel port. LED and another one goes to any of the ground pins. Be sure to fit the circuit so that the LED positive lead the longer. If you put the led in the wrong way, it will. You can connect one circuit to each of the parallel port data pins. In this way you get eight software controllable LEDs. When you send out 1 to the datapin where the. LED is connected, that LED will light. When you send 0 to that same pin. LED will no longer light. Here are two photos of circuit above I have built. Pn those circuits I have wired the ground wire only to one ground pin it works also well, you can use any of the ground pins. Technical specifications of parallel port pins. The IBM specifications says accoding http www. IO Port Programming 6. The data output pins pins 2 9 sink 2. A, source 1. 5 m. A, and their high level output is min. V. The low state for both is max. V. Pins 1, 1. 4, 1. V through 4. 7 kiloohm resistors sink 2. A, source 0. 5. 5 m. A, high level output 5. V minus pullup. Non IBM parallel ports probably deviate from this standard. Warning Be careful with grounding. You can break parallel ports by connecting devices to them when PC is powered on. It is not a good idea to short the pins to ground or 5. V, this can damage the port. It might be a good thing to use a parallel port not integrated on the motherboard for things like this. You can usually get a second parallel port for your machine with a cheap standard multi IO card. The following program is an example how to control parallel port LPT1. This example directly controls the. It works nicely under. MSDOS. You can look the Borland Pascal 7. LPTOUT. EXE. This has worked nicely for me in DOS systems and Windows 9. On recent testings this program has worked unreliably on some Windoes 2. Program lpt. 1output. Mem. W0. 04. 0 0. ValParam. Str1,data,e. Portaddr data. How to use the program. LPTOUT. EXE is very easy to use program. The program takes one. That value must be integer in decimal format for example 2. Hexadecimal numbers can also be used, but they must be preceded by. FF. The program hoes not have any type of error. If your number is not in correct format. NOTE I have found out that this program does not work reliably on. Windows 2. 00. 0 systems I have tested on this. I dont know. what is causing this specific problem other than you should not. Windows NT based system. I have not tested this program with Windows XP. Example how to use the program. LPTOUT 0. Set all datapins to low level. LPTOUT 2. 55. Set all datapins to high level. LPTOUT 1. Set datapin D0 to high level and all other datapins to low level. What You Need to Know About Pegasus, Microsofts Upcoming Handheld Device October 1. What You Need to Know About Pegasus, Microsofts Upcoming Handheld Device. Jeffrey Richter. Jeffrey Richter wrote Advanced Windows Microsoft Press, 1. Windows 9. 5 A Developers Guide M T Books, 1. Jeff is a consultant and teaches Win. He can be reached at v jeffrrmicrosoft. I have become completely dependent on my computer for all sorts of things. Obviously, I use my computer to develop software, but I also use my computer for banking, email, my personal phone book, my appointment schedule, playing games, and so on. I am not quite at the point where I leave my machine on 2. I will be able to carry a computer in my pocket during those rare hours my desktop machine is not at easy reach like when Im flying back and forth between Seattle and San Francisco. This computers official name has not been announced yet, but its codename is Pegasus. Its being created by Microsoft with six hardware partners. Ill start by showing you the Pegasus hardware from the users perspective. In the second part of this article Ill dive into the details of the software platform and discuss the programming issues you need to understand to write cool Pegasus apps. What is Pegasus Microsoft has been trying for years to come up with a hand held computing device. First, there was Win. Pad. The Win. Pad machine ran on x. CPUs only and had a stripped down version of 1. Windows 3. 1 as its operating system. The system didnt have a keyboard, but instead used handwriting recognition as its input method making the machine a poor input device. Its estimated price was 7. After extensive research, Microsoft felt that consumers would not pay the high price for this limited system and abandoned the project. Next, Microsoft embarked on Pulsar. It was designed to be a super pager a wireless product with a very small screen and no keyboard just a few buttons. Microsoft hoped the simplicity of the device would interest consumers who had never even used a computer before. Again, Microsofts research told them that the world was not ready for such a device and Pulsar was also scrapped. At this point, Microsoft went back to the drawing board and came up with something totally new Pegasus. What makes the Pegasus project different from Win. Pad and Pulsar Microsoft reduced its intended consumer base and defined a product to meet their needs. Pegasus can be a standalone device, but this is not how Microsoft intends it to be used. Pegasus is a companion device that will most likely be used with a Windows 9. Windows NT based desktop machine. As of mid 1. 99. This means the Pegasus audience is restricted mainly to Windows users not everyone in the world who uses a Day Timer or some other paper information manager. In fact, the two most important features of Pegasus are that it looks and feels like Windows and that it connects very well with a Windows based desktop machine. Ill discuss these features in more detail shortly. Lets first look at the actual Pegasus hardware platform. The Pegasus Hardware Platform. The Pegasus project consists of two parts hardware and software. Because Microsoft does not want to get into the hardware business for the moment lets forget that they make mice, keyboards, and joysticks, they signed up six partners Casio, Compaq, HP, LG Electronics, NEC, and Philips to create the hardware based on a reference platform defined by Microsoft. A Pegasus machine is guaranteed to have an embedded keyboard, including alphanumeric keys, standard punctuation keys, a Control key, an Alt key, and two Shift keys. Infrequently used keys like Insert, Pause, Scroll Lock, Print Screen, function keys, and the new Windows Start key are optional. Note that some international versions of Pegasus, like Japanese and Chinese, may not have keyboards due to the complexity of the character set. These versions will use handwriting recognition as their main source of input. Also, since Pegasus is going to be marketed worldwide, all Pegasus machines use Unicode. Pegasus will also have an embedded touch screen 4. A docking cradle will recharge the machines batteries and connect the Pegasus to your desktop machine more on this later. It must feel like it can be worn on the body rather than being lugged around, so the device must not exceed 7. The Pegasus will include one PCMCIA slot, one serial connector, one infrared port Ir. DA, at least 2. MB of RAM for the file system and running applications, and 4. MB of ROM. The Pegasus Operating System. Pegasus introduces a new operating system from Microsoft that is super lightweight. The good news is that the Pegasus OS is a Win. OS, which means that you already know how to develop software for it. The bad news is that this new kernels functions have many little nuances and implementation details that are yet to be discovered by poor unsuspecting souls like you and me. To keep the kernel small, many of the Win. While this lightweight kernel is making its debut in Pegasus, it is not specific to Pegasus. Microsoft intends to incorporate this kernel into other devices. In the not too distant future you can expect to see this lightweight kernel used for the global positioning system in your automobile, in your television set, and in other household appliances. The software opportunities are enormous. Since memory is limited, the Pegasus OS is small. It requires about 1. KB of ROM and about 4. KB of RAM to run. The system is also portable. Currently, versions exist for the Hitachi SH3, MIPS, and x. Since each of these processors use different instruction sets, Pegasus app developers will need to produce binary images for each of these processors. The Pegasus SDK does this for you see the sidebar for more information on the Pegasus SDK. The Pegasus Shell and User Interface. Figure 1 shows the Pegasus desktop. As you can see, there is a striking resemblance to Windows 9. Windows NT 4. 0. The shell includes the desktop, the taskbar, and a recycle bin. The taskbar is always visible and is the quickest way for the user to switch from one application to another. A nice feature of the Pegasus taskbar is the ability to minimize an active window by clicking on its button in the taskbar. The Start button offers the same features as seen on Windows NT and Windows 9. One big difference is that Pegasus does not support cascading menus menu options that normally display a hierarchical menu now open a window that allows the user to go to the next level. The taskbar also supports those little icons, which are used quite frequently to notify the user of various events. Figure 1 Pegasus desktop. Pegasus does support shell links, but the normal way of creating and interacting with them using the IShell. Link COM interface is not supported because Pegasus does not currently support COM. Instead, Pegasus offers two new functions, SHCreate. Shortcut which creates a shortcut and SHGet. Shortcut. Target which returns the thing that the shortcut refers to. You can use Explorer to locate files, drag and drop files, and execute applications. From the Start menu you can start applications, work on recently used documents, get help, visit the Control Panel, and suspend the machine. Programmers can write Control Panel applets to run under Pegasus. Unlike Windows 9. Windows NT, Pegasus has some limitations in its windowing subsystem.