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  • How to determine the port numbers for peripheral devices?

    - by smwikipedia
    I know that peripheral devices such as a hard driver, a floppy driver, etc are controlled by reading/writing certain control registers on their device controllers. I am wondering about the following questions: Is it true that when these peripheral devices are plugged onto the computer, the addresses(port numbers) of their control registers are thus determined by how they are attached to the address bus (i.e. the hard-wiring rules, not any soft things)? Who makes the scheme of the port number assignment? If I was given a naked computer(with no operating system and with many peripheral devices), how could I figure out the port number assignment so I can use them to control peripheral deveices. At last and as usual, thanks for your patience and reply. 8^)

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  • Is there any data missing?

    - by smwikipedia
    Hi experts, Here is some code quoted from Douglas.E.Comer's < Computer Networks and Internets 4th edition. This program will send back any data it received. ... while((len = recv(conn, buff, BUFFERSIZE,0)) >0) // receive data send(conn, buff, len, 0); // send it back ... I am wondering, what if some data arrived when the code is executing in send(..) function, will it miss that data? Because the recv() function is not being executed. If no data is missed, where is the data kept? And by whom? Thanks...

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  • Does all the network card use the same frequency to send signals to wire?

    - by smwikipedia
    Hi, I am comparing my cable TV wire to my network wire. In a TV cable wire, different frequencies are used by different TV channels. And since a certain channel use a fixed frequency, I think the only left way to represent different signal is with the carrier wave's amplitude. But what about the network wire? For all the network card with the same type, do they also use different frequencies to send signals just like TV cable? I vaguely remember that they use frequency adjustment to represent signals. So the frequency should not be a fixed one. So how did all the network cards that sharing the same medium differentiate their own signal from others?

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  • How to determine the port numbers for peripherals devices?

    - by smwikipedia
    I know that peripheral devices such as a hard driver, a floppy driver, etc are controlled by reading/writing certain control registers on their device controllers. I am wondering about the following questions: Is it true that when these peripheral devices are plugged onto the computer, the addresses(port numbers) of their control registers are thus determined by how they are attached to the address bus (i.e. the hard-wiring)? Who makes the scheme of the port number assignment? If I was given a naked computer(with no operating system and with many peripheral devices), how could I figure out the port number assignment so I can use them to control peripheral deveices.

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  • How to R/W hard disk when CPU is in Protect Mode?

    - by smwikipedia
    I am doing some OS experiment. Until now, all my code utilized the real mode BIOS interrupt to manipulate hard disk and floppy. But once my code enabled the Protect Mode of the CPU, all the real mode BIOS interrupt service routine won't be available. How could I R/W the hard disk and floppy? I have a feeling that I need to do some hardware drivers now. Am I right? Is this why an OS is so difficult to develop? I know that hardwares are all controlled by reading from and writing to certain control or data registers. For example, I know that the Command Block Registers of hard disk range from 0x1F0 to 0x1F7. But I am wondering whether the register addresses of so many different hardwares are the same on the PC platform? Or do I have to detect that before using them? How to detect them?? For any responses I present my deep appreciation.

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  • Question about SSL Certificate.

    - by smwikipedia
    Hi experts, I am trying to make a SSL connection to a web site. Each time I enter the https:// address and press enter, the IE8 prompts me to select the Certificate (Client Certificate) to send to the server. I got 2 certificates to choose from. And they are stored in the IE8 - Internet Options - Content - Certificates - Personal. Since my server and client are the same machine, I want to use a single certificate for both server and client. And this certificate is a IIS generated self signed certificate. I do the following steps: 1- Generate a self-signed-cert in IIS; 2- Bind my site to https and choose the above self-signed-cert 3- Import the self-signed-cert at the IE8 - Internet Options - Content - Certificates - Personal. Then I use the https link to access my page, it is still prompts me to choose a certificate. But I cannot see my newly imported self-signed-cert. Why?

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  • What is the different purpose of .H header file and a IDL file?

    - by smwikipedia
    I am studying COM so there're some basic questions puzzling me... I know that IDL file is used to describe the method definitions (or the so called 'contract' between software modules), and the .H header files contains something like a method prototype, which looks similar to what the IDL is meant for. So, why are these two things coexist? Isn't one enough? Many thanks.

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  • Mis-spelling in the .NET configuration system, a design flaw?

    - by smwikipedia
    I just wrote some .NET code to get connection string from the config file. The config file is as below: <?xml version="1.0" encoding="utf-8" ?> <configuration> <appSettings> <add key="key1" value="hello,world!"/> </appSettings> <connectionStrings> <add name="conn1" connectionString="abcd"/> </connectionStrings> </configuration> .NET Framework provide the following types to get the connection string: 1- ConnectionStringsSection : stands for the config section containing several connection strings 2- ConnectionStringSettingsCollection : stands for the connection string collection 3- ConnectionStringSettings : stands for a certain connection string. .NET Framework also provide the following types to get the App Settings: 4- AppSettingsSection 5- KeyValueConfigurationCollection 6- KeyValueConfigurationElement Compare 2 to 5, 3 to 6, why are there extra "s" in ConnectionStringSetting[s]Collection and ConnectionStringSetting[s]? This mis-spelling is really mis-leading. I think it's a design flaw. Has anyone noticed that?

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  • [.NET] What's the point of MarshalByValue Object?

    - by smwikipedia
    Hi awesome! We know that MarshalByRef allow us to create an object in a different AppDomain and use a Proxy object to access it. And the behavior of that object is in a different context of the AppDomain where it actually lives in. Well this sounds faily reseaonable in the regard of isolation and safety. But why is there still MarshalByValue? MarshalByValue just leads to an newly deserialized object which is an exact copy of the object in a different AppDomain. If we need that object, why not just create it in the current AppDomain? Why bother to first create it in a different AppDomain and then get it back by MarshaoByValue? Many thanks.

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  • Question about regex in linux commands.

    - by smwikipedia
    I ran the following command at linux bash: apt-cache search hex.*(view|edit) My intention was to find any software packages whose name/description contains the pattern 'hex.*(view|edit)'. But among the results I got this: kipi-plugins - image manipulation/handling plugins for KIPI aware programs How could this be in the results list? I didn't see any matching string in this result. Is this a bug of the apt-cache search command? Or do I mis-understand how the regex is used by this command? Many thanks.

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  • How to set full control to a directory??

    - by smwikipedia
    I am using the following simple code to add full control to a directory, but it doesn't work. String dir_name = @"folder_full_path"; DirectorySecurity dir_security = Directory.GetAccessControl(dir_name); FileSystemAccessRule access_rule = new FileSystemAccessRule(@"AccountName", FileSystemRights.FullControl, AccessControlType.Allow); dSecurity.AddAccessRule(access_rule); Directory.SetAccessControl(dir_name, dir_security); But this code only set special permissions to the target folder. This code is almost the same as the MSDN sample. I am scratching my head for a reasonable explanation... Hope someone could shed some light on me. Many thanks.

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  • Where is the root [closed]

    - by smwikipedia
    I read the manual page of the "mount" command, at it reads as below: All files accessible in a Unix system are arranged in one big tree, the file hierarchy, rooted at /. These files can be spread out over several devices. The mount command serves to attach the file system found on some device to the big file tree. My question is: Where is this "big tree" located?

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  • [VB.NET] Same name methods in different modules cause ambiguity.

    - by smwikipedia
    I have 2 modules. Each contains a Sub with the same name. See below: Module moduleA Public Sub f(ByVal arg1 As myType) Console.WriteLine("module A") End Sub End Module Module moduleB Public Sub f(ByVal arg1 As myType, ByVal arg2 As Boolean) Console.WriteLine("module B") End Sub End Module But the compiler complains that there's ambiguity between moduleA and moduleB. How could this be? I have totally different signatures. However, if I put the 2 methods into the same module, there's no ambiguity at all. Could someone tell me why? Many thanks.

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  • The cross-thread usage of "HttpContext.Current" property and related things

    - by smwikipedia
    I read from < Essential ASP.NET with Examples in C# the following statement: Another useful property to know about is the static Current property of the HttpContext class. This property always points to the current instance of the HttpContext class for the request being serviced. This can be convenient if you are writing helper classes that will be used from pages or other pipeline classes and may need to access the context for whatever reason. By using the static Current property to retrieve the context, you can avoid passing a reference to it to helper classes. For example, the class shown in Listing 4-1 uses the Current property of the context to access the QueryString and print something to the current response buffer. Note that for this static property to be correctly initialized, the caller must be executing on the original request thread, so if you have spawned additional threads to perform work during a request, you must take care to provide access to the context class yourself. I am wondering about the root cause of the bold part, and one thing leads to another, here is my thoughts: We know that a process can have multiple threads. Each of these threads have their own stacks, respectively. These threads also have access to a shared memory area, the heap. The stack then, as I understand it, is kind of where all the context for that thread is stored. For a thread to access something in the heap it must use a pointer, and the pointer is stored on its stack. So when we make some cross-thread calls, we must make sure that all the necessary context info is passed from the caller thread's stack to the callee thread's stack. But I am not quite sure if I made any mistake. Any comments will be deeply appreciated. Thanks. ADD Here the stack is limited to user stack.

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  • Why I cannot get the output of ftp.exe ?

    - by smwikipedia
    I execute the ftp.exe cmd through a C# System.Diagnostics.Process type. And I use the following code to get the "ftp.exe" output after I programmatically enter a "help" command. But I can only get the first line of the result. And I never get to the "end" output part. The whole program seems blocked. Process p = new Process(); p.StartInfo.FileName = @"C:\Windows\System32\ftp.exe"; p.StartInfo.CreateNoWindow = true; p.StartInfo.RedirectStandardInput = true; p.StartInfo.RedirectStandardOutput = true; p.StartInfo.RedirectStandardError = true; p.StartInfo.UseShellExecute = false; p.Start(); p.StandardInput.WriteLine("help"); Int32 c_int = p.StandardOutput.Read(); while (c_int != -1) { Char c = (Char)c_int; Console.Write(c); c_int = p.StandardOutput.Read(); } Console.WriteLine("end"); However, I write a simple program which only use Console.Writeline() to write some output to its StdOut stream. And I test it with the above code. It works fine. I just cannot figure out why the above code cannot work with ftp.exe? The only difference between my SimpleConsoleOutput program and the "ftp.exe" is that the ftp.exe has its own interactive command prompt.

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  • Why I cannot get the output of ftp.exe by code?

    - by smwikipedia
    I execute the ftp.exe cmd through a C# System.Diagnostics.Process type. And I use the following code to get the "ftp.exe" output after I programmatically enter a "help" command. But I can only get the first line of the result. And I never get to the "end" output part. The whole program seems blocked. Process p = new Process(); p.StartInfo.FileName = @"C:\Windows\System32\ftp.exe"; p.StartInfo.CreateNoWindow = true; p.StartInfo.RedirectStandardInput = true; p.StartInfo.RedirectStandardOutput = true; p.StartInfo.RedirectStandardError = true; p.StartInfo.UseShellExecute = false; p.Start(); p.StandardInput.WriteLine("help"); Int32 c_int = p.StandardOutput.Read(); while (c_int != -1) { Char c = (Char)c_int; Console.Write(c); c_int = p.StandardOutput.Read(); } Console.WriteLine("end"); However, I write a simple program which only use Console.Writeline() to write some output to its StdOut stream. And I test it with the above code. It works fine. I just cannot figure out why the above code cannot work with ftp.exe? The only difference between my SimpleConsoleOutput program and the "ftp.exe" is that the ftp.exe has its own interactive command prompt.

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