DosTips.com

foxidrive wrote:Do you mean Win64 bit compatible? 32 bit Windows can run .com files.

Aacini wrote:I only use the best: assembly language!

More than 25 years ago I wrote several small programs as auxiliary commands for Batch files. They were really small files, less than 400 bytes the majority. For example, below is my GetKey program that read a key from keyboard and return its Ascii code via ERRORLEVEL. This is the MS-DOS 16-bits version:

Code: Select all

mov   ah,8         ;DOS function: Keyboard input without echo
int   21H         ;AL = Ascii code of key pressed
mov   ah,4CH      ;DOS function: Terminate program
int   21H         ;Return Ascii code via ERRORLEVEL

This program generate a .COM file 8 (eight) bytes long! This program requires several modifications to make it Windows 32-bits compatible, so the resulting .EXE file is 1,536 bytes long! (although many of these are zero-filled bytes required in .EXE file format).

Antonio

Fawers wrote:

Aacini wrote:I only use the best: assembly language!

More than 25 years ago I wrote several small programs as auxiliary commands for Batch files. They were really small files, less than 400 bytes the majority. For example, below is my GetKey program that read a key from keyboard and return its Ascii code via ERRORLEVEL. This is the MS-DOS 16-bits version:

Code: Select all

mov   ah,8         ;DOS function: Keyboard input without echo
int   21H         ;AL = Ascii code of key pressed
mov   ah,4CH      ;DOS function: Terminate program
int   21H         ;Return Ascii code via ERRORLEVEL

This program generate a .COM file 8 (eight) bytes long! This program requires several modifications to make it Windows 32-bits compatible, so the resulting .EXE file is 1,536 bytes long! (although many of these are zero-filled bytes required in .EXE file format).

Antonio

I find Assembly very interesting, yet hard to learn; I just can't understand what all those MOVs and INTs stand for.

Mov ah,8       Move in the register AH (like a variable) the value 8
int 21H          Call the interrupt number 21Hex (like a subroutine in the bios or emulated)
                   ah=8 is like a parameter/index for the function/subroutine in the bios code

Aacini wrote:I only use the best: assembly language!

More than 25 years ago I wrote several small programs as auxiliary commands for Batch files. They were really small files, less than 400 bytes the majority. For example, below is my GetKey program that read a key from keyboard and return its Ascii code via ERRORLEVEL. This is the MS-DOS 16-bits version:

Code: Select all

mov   ah,8         ;DOS function: Keyboard input without echo
int   21H         ;AL = Ascii code of key pressed
mov   ah,4CH      ;DOS function: Terminate program
int   21H         ;Return Ascii code via ERRORLEVEL

This program generate a .COM file 8 (eight) bytes long! This program requires several modifications to make it Windows 32-bits compatible, so the resulting .EXE file is 1,536 bytes long! (although many of these are zero-filled bytes required in .EXE file format).