Branches Tags. Could not load branches. Could not load tags. Latest commit. Git stats 35 commits. Failed to load latest commit information. View code. Assembly Cheatsheet It's a great cheat sheet to helps you remember stuff in assembly programming. I used it to pass my assembly exam : Content list Code Structure Intrupts Working with strings Working with files Procedures Time Graphics Drawing a pixel Basic Structure Each assembly program should start with this style below: stk segment stack 'stack' dw 32 dup?
Releases No releases published. Packages 0 No packages published. You signed in with another tab or window. Type the following command to kill process of notepad from process. This command forcefully shut down all the processes that are not responding. Note: taskkill may not work on xp home edition, in that case use tskill command. Start: The start command is an internal command that is available in the below Microsoft operating systems.
Excellent post. I was looking for this particular info for a long time. Thank you and best of luck. Save my name, email, and website in this browser for the next time I comment. Trending How to use Chrome Password Manager? And how safe is it? This function:. DOS 3. The country-dependent information returned by DOS 2. To get country-dependent information for the current country, call this Function with 00h in AL. To get information for another country, specify the appropriate country code in AL.
To specify a country code larger than fdh , place ffh in AL and the bit country code in BX. The DOS case-mapping routine whose address as segment:offset is returned with the country dependent information will map character values from 80h to FFh to their uppercase equivalents.
To use this routine, first place the character to be mapped to uppercase in the AL register. The uppercased character will be returned in the AL register.
If the function is unable to create the directory, it sets the carry flag and returns an error code in AX. If the function is unable to delete the directory, it sets the Carry Flag and returns an error code in AX. The path name may include a drive letter. Warning: If a file with the specified name already exists, it is truncated to zero length, effectively deleting the old data from the file.
Information can be written to a file created in Read-only mode. However, using this function to open an existing read-only file will generate an error. The function opens any existing file, including hidden files, and sets the record size to 1 byte. The low-order three bits access mode are used in the same manner in both DOS 2 and 3.
In DOS 3. These bits govern the manner if any in which other users on a network may open and use the file after you have opened it. The following settings and no others are valid:. The Inheritance Flag bit 7 , specifies whether or not child processes will inherit the use of this file.
If bit 7 is 0, child processes automatically have access to the file. If bit 7 is 1, the file is not automatically available to child processes.
Once a file has been opened by a process, the availability of that file to other processes is determined by both the sharing mode and access mode of the original process as well as by the sharing mode and access mode specified by the subsequent process. Here is a case-by-case overview of these interactions:. The file is first opened in compatibility sharing mode.
A file in compatibility mode may be opened any number of times by a single process, unless the file is already open under one of the other four sharing modes. If the file has the read-only attribute, however, and it is currently open in Deny Write sharing mode with Read access, the file may be opened in Compatibility mode with Read access.
This function reads data from the file or device whose handle is in BX. Data is read starting at the location pointed to by the file pointer. The file pointer is incremented by the number of bytes read. If the Carry Flag is not set and AX is less than the number of bytes requested, either the function read to the end of the file, or an error occurred.
You can read bytes from anywhere in the file by calling function 42h to move to file poniter before reading data. If the keyboard device is specified, this function reads either the specified number of bytes, or all bytes up to the next carriage return, whichever is less. If the number of bytes specified is at least two larger than the number of characters typed, the carriage-return line-feed pair will be returned as the last two bytes, and will count as two bytes.
This function writes data to the file or device whose handle is in BX. Data is written starting at the current file pointer. The file pointer is then incremented by the number of bytes written. If a disk full condition is encountered, no error code will be returned i.
You should check for this condition by testing for AX less than CX after returning from the function. You can write bytes to anywhere in the file by calling function 42h to move to file poniter before writing data. Wildcard characters may not be used in the pathname specification. Note that the corresponding FCB function, Function 13h, does permit wildcard characters. Move the file-pointer the specified number of bytes from the beginning, end or current location, as determined by the mode code in AL.
The offset to add to the file pointer is given as a signed bit integer in the CX:DX register pair—the more significant portion of the offset in CX. No matter what mode is specified in AL, a positive offset value in CX:DX always increases the value of the file pointer. Note that using mode 2 with a positive value in CX:DX will therefore move the file pointer beyond the end of the file. Use a mode code of 2 with an offset of 0 to move the file pointer to the end of the file, or to find the length of the file.
It is possible to move the pointer to a location before the beginning of the file or after the end of the file. Moving the pointer to a position before the start of the file will not generate an error, but the next read or write operation will fail. A file can be extended by moving the file pointer past the end of the file and writing one or more bytes of data.
A file can be truncated my moving the file pointer to the new end of file and writing zero bytes using function 40h. This function returns or sets the attribute byte of the specified file. To determine the current attributes, put 00h in AL; the attribute byte is returned in CX. To set attributes, put 01h in AL and the desired attribute byte in CX. Only subfunctions 00h, 06h, and 07h are defined for files. In all cases, the subfunction to be performed is determined by the value in AL, as follows:.
Subfunctions 00h and 08h are not supported on network devices. Subfunction 00h returns device information in DX. Bit 7 of DX is 1 if the channel is a character device, and 0 if the channel is a block device disk file. Subfunction 01h sets device information for character devices, using the following encoding scheme in DX:. How data is read is defined by the device driver. Data can be read only if the device can process control strings.
How data is written is defined by the device driver. Data can be written only if the device can process control strings. This subfunction reports the input status of the device or file. AL returns FFh for ready and 00h for not ready or end of file. This subfunction DOS 3. A value of 00h in AX means the device is removable; a value of 01h means it is fixed. AX returns an error code of 0Fh if an invalid drive has been specified in BL. For local devices, DX returns the attribute word from the device header; for remote devices, DX returns with bit 12 set.
For local handles, DX returns the attribute word from the device header; for remote devices, DX returns with bit 15 set. Specify the number of retries in DX and the number of delay loops between retries in CX. The default values are 3 retries and 1 delay loop. SHARE needs to be loaded before using ths subfunction.
Returns the drive letter used most recently for block devices that have more than one logical drive letter. Some block devices use more than one drive letter to refer to the same device. For example, the floppy disk drive on a system with only one floppy disk drive can be referred to as either A: or B:. This function tells both if more than one drive letter refers to a device and, if so, which drive letter was used most recently.
Sets the drive letter used most recently to refer to a device that has more than one drive letter. This function sets the drive letter used most recently to refer to a drive. Creates a new file handle by duplicating the existing handle of an open file or device. The new handle shares the existing file pointer. Function 45h DUP returns a new file handle that refers to the same file or device as the old file handle specified in BX.
Moving the file pointer of either handle by a Read, Write, or Lseek causes the other handle to be changed also. However, closing one handle does not close the other. This function causes the second handle in CX to refer to the same file, at the same location, as the first handle in BX. If the second handle refers to an open file, that file is closed before the handle is set equal to the first handle. This function returns the full pathname of the current directory, excluding the drive designator and initial backslash character, as an ASCIIZ string at the memory buffer pointed to by DS:SI.
The pathname may be as long as 63 bytes without the initial backslash , plus the terminating zero byte. If the current directory is the root, the function returns a null ASCIIZ string that is, the first byte of the buffer will be zero. In some versions of DOS prior to 3.
For example, this function under DOS 2. Note that this path is in lower case and contains too many characters. Function 48h dynamically allocates memory, in multiples of 16 bytes one paragraph. The amount of memory to be allocated, in paragraphs, is specified in BX.
If the function is successful, AX points to the allocated memory block. AX holds the segment address; the offset is always The call will return an error, which can be ignored, since DOS cannot allocate more than k of memory.
This function returns to DOS the memory that was allocated by means of Function 48h. ES points to the segment address of the block that is being returned; this is the same value that Function 48h returned in AX.
This function is used to increase or decrease the size of a memory block allocated by Function 48h. ES contains the segment address of the block whose size will be changed. BX contains the new size of the block, in paragraphs bytes units. The terminate and Ctrl-Break vectors are set to the instruction following the EXEC call, so that control returns to the calling program as soon as the subprogram ends.
If AL is 03h, the subprogram is loaded, no PSP is created, and the subprogram is not automatically executed, although your program can jump to it. And load the ES:BX pair with a pointer to a parameter block to be passed to the incoming subprogram. The parameter block layout is as follows:. The environment strings, which must be paragraph-aligned, consists of a sequence of ASCIIZ strings followed by a byte of 00h after all the strings.
The total environment string must be less than 32K in length. If the segment for the environment strings is set to 00h, the subprogram inherits the environment of the calling program. When a subprogram is loaded and executed, all open file handles are available to the subprogram.
That means, among other things, that the calling program can redirect standard input and output for the subprogram.
The only file handles that are not available to the subprogram are those that were opened with the inheritance bit set to 1 see Function 3Dh. Before using Function 4Bh, you must release enough memory to load the subprogram using function 4Ah. This function changes all registers, including the stack registers. Therefore, before calling a subprogram, save SS and SP in variables inside your program code.
This function is the proper method of terminating a program in DOS versions 2.
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