Software
DOSBOX
If you have a sytem with Windows 8 and higher as an operating system - you will not have access to the command line prompt. In this case you can use DOSBOX. Download the software from the link below. The setup file is executable just run it - DosBox gets installed automatically.
If you have a Linux system - you can refer to this Wiki on DosBox in Ubuntu. It gives all details on installation and usage of DosBox in Ubuntu
https://help.ubuntu.com/community/DOSBox
MASM611
Microsoft Assembler- Download the software from the link. Extract the files into any Folder of your choice. The MASM executable will be in MASM611/BIN
Debug & DebugX
Debugger - To test output/behavior of Programs. Download the software from the link. Extract the files into MASM611/BIN Folder