.386 .model flat, stdcall option casemap:none .data .data? .Const .code Start: End Start
.386 It is the assembler directive, which tells to use the 80386 instruction set. There are many predecesor of this like 80486, 80586,etc .model flat, stdcall It tells which memory model to use. Under win32, there is only one memory model i.e flat. Under DOS, memory is divided in 64k segments but under win32, momory is devided in 4GB seg. Therefore, you need not to take of segment registers under win32. stdcall This is used to tell, which convention is to be used, means in a function, parameters are passed left to right in stack or right to left and who will adjust the stack once function is finished it's procedure. Generally, parameters are passed right to left in stack and it is the duty to callee to adjust the stack.MODEL is an assembler directive that specifies memory model of your program. Under Win32, there's only on model, FLAT model.MODEL is an assembler directive that specifies memory model of your program. Under Win32, there's only one model, FLAT model. option casemap:none This tell to consider words differently except few identifiers. Example: name and Name are different There are mainly two sections viz Data and Code section. Data seciton is divided into 3 sections viz Data, .Data? and Const .data This section is used to declare the variables and initializing them here. Example: MessageTxt db "Hello World" This seciton constitutes the size of executable. .data? This section is used for declaring uninitialized variables like buffer. This section doesn't constitute the size of executable. Variables are initialized at runtime .Const This section is similar to .data section but with one condition i.e it is read only. So, once you declare here, then it can't be changed. .Code As you would have already guessed what comes in this section. This section includes the whole logic of your program. Start: End Start Code Section begins with a label. It isn't need to be Start means you can name it anything but it should end with "End" keyword.
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