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I just can't recall, but searching... Will let you know.
I've found two similar books on the net, but the one I was writing is building a hex-editor step by step.

Try to find Peter Norton's book on ASM, I felt in love with Assembly while studying his book.
He's got humour, style, and is a great teacher. He introduces you step by step in the world of assembly...

We'd need an "Assembly" room, too, isn't it?
Btw, you'd try to optimize your code - it is the real spice of assembly.
e.g.
instead of
mov al,00h -> xor al, al
and so on.

Have fun, ASM is the...