I am from Nepal. Its definite that nobody here can buy licensed copy of Photoshop. People ocassionally buy original Antivirus copies. Selling software in such a market is tough. I have just completed Bachelor of Software Engineering. Developing countries are being able to provide world class education but market is definitely not what they can provide. Creating this software was my friend's idea and he is definitely going to give me share from his earning by making cards but selling software in developing countries is tough since people still think intangible things should be free. Changing this mindset is a big challenge and I am still trying to convince some of the potential customers.
The best book for this is "Elements of Computing System" by Noam Nisan and Shimon Schocken. It starts from basic gates and then higher to build more complex parts. The book website provides all the necessary emulators and programming tools that help you to build a emulated computer and then build OS and application softwares on top of it. I have not really gone through the whole book and practiced what it wants to teach us because of my busy academic schedules but hope to complete it someday soon.