Thank you both for looking at this. As good as the Nasm manual is, I could not quite figure out if my understanding of defining data sizes was correct. Frank, you confirmed that I have it correct - thank you.
I have a chunk of code, converting ascii to floating point and back again, that I am changing over from masm format to Nasm. I did not write the code; it was written by Richard Detmer, author of "Introduction to 80x86 Assembly Language and Computer Architecture" and taken from his book. The code is working more or less, but is having one or two "sizing" issues. I'm still a bit rusty. And Bryant, thank you for reminding me that the D in DB and DW etc. stands for define. I keep tripping over data as in data byte rather than define byte.
Thank you for the clarifications.
BTW, speaking of books, most likely you are aware of these, but I will mention them in case someone else wants the information. Detmer's book I have already mentioned. It is good for anyone who is interested in developing Windows assembly language programs using MS Visual Studio. It is possible to develop pure assembly language projects in MSVC, even the free Express version.
Personally, I prefer the Linux world and there are some good books that address assembly language programming in Linux using the Nasm assembler. Jeff Duntemann's "Assembly Language Step by Step" 3rd ed. This is an excellent book, especially for a beginner. Some have complained that it moves too slowly, but I appreciate the extra detail, and he writes with some humor.
Dr. Paul Carter's "PC Assembly Language." Dr. Carter's book is free in pdf format, and the printed book is not very expensive. He provides a good treatment on the co-processor. Sivarama P. Dandamudi's book "Guide to Assembly Language Programming in Linux" is an excellent book! I also have Bob Neveln's "Linux Assembly Language Programming," but I have never used it. In leafing through it, he appears to be giving some good examples on talking to the hardware.
There are a couple of others - Blum's book if you are into Gas and the AT&T syntax. Also for those interested in doing 64 bit asm using Nasm - Seyfarth's book, "Introduction to 64 Bit Intel Assembly Language Programming for Linux." I have a 64 bit machine that I am just starting to play with using this book, but I cannot say how good the book may or may not be. At first blush, it appears very good, but I need a lot more brushing up in the 32 bit world before jumping into the deep end.
Thanks for doing Nasm!
~jiangshi