ABSTRACT
Preamble This chapter introduces the services available to the Windows programmer, but from a viewpoint that you would expect of a book on assembly language. I have covered two major aspects: the DOS services and the Windows low-level services. This chapter gives an overview, and the next chapter provides practical code. We haven't been so far away from the operating system in earlier chapters, but now is the time to delve in further. In this chapter I have particularly been concerned about the relationship between DOS and Windows. We have a new operating system running on top of DOS, with the CPU in Protected mode — how much of the old DOS can we still use? Then there is the related issue of how DOS itself has been changed to handle the new CPUs and operating conditions. What are these
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changes? For example, INT-16h, the keyboard handler under DOS, doesn't work under Windows. I have already mentioned the problem of calling the old DOS interrupt services with the CPU running in Protected mode (page 33). I introduced some of the first DOS services to utilize Protected mode (page 18).
