Re-organized the files for readability.

Makefile

@@ -7,29 +7,12 @@ help:                 ## Print this help message
 		sort -nr | head -1) && \
 		perl -ne "m/^((\w|-)*):.*##\s*(.*)/ && print(sprintf(\"%s: %s\t%s\n\", \$$1, \" \"x($$M-length(\$$1)), \$$3))" Makefile
 
-hello32: hello32.s    ## Build the 32 bit version of Project 2
-	nasm -f elf hello32.s
-	ld -m elf_i386 -o hello32 hello32.o
-
-hello64: hello64.s    ## Build the 32 bit version of Project 2
-	nasm -f elf64 hello64.s
-	ld -o hello64 hello64.o
-
-counted-hello32: counted-hello32.s    ## Build the 32 bit version of Project 3
-	nasm -f elf counted-hello32.s
-	ld -m elf_i386 -o counted-hello32 counted-hello32.o
-
-counted-hello64: counted-hello64.s    ## Build the 32 bit version of Project 3
-	nasm -f elf64 counted-hello64.s
-	ld -o counted-hello64 counted-hello64.o
-
-subroutine-hello32: subroutine-hello32.s    ## Build the 32 bit version of Project 3
-	nasm -f elf subroutine-hello32.s
-	ld -m elf_i386 -o subroutine-hello32 subroutine-hello32.o
-
-subroutine-hello64: subroutine-hello64.s    ## Build the 32 bit version of Project 3
-	nasm -f elf64 subroutine-hello64.s
-	ld -o subroutine-hello64 subroutine-hello64.o
+all:				## Make everything in all trees
+	cd x86 && make all
+	cd x86_64 && make all
 
 clean:                ## Delete all built and intermediate features
-	rm -f hello32 hello64 counted-hello32 counted-hello64 *.o
+	cd x86 && make clean
+	cd x86_64 && make clean
+
+include ./makefiles/help.make

makefiles/help.make

@@ -0,0 +1,4 @@
+run-help:                 ## Print this help message
+	@M=$$(perl -ne 'm/^((\w|-)*):.*##/ && print length($$1)."\n"' Makefile | \
+		sort -nr | head -1) && \
+		perl -ne "m/^((\w|-)*):.*##\s*(.*)/ && print(sprintf(\"%s: %s\t%s\n\", \$$1, \" \"x($$M-length(\$$1)), \$$3))" Makefile

x86/Makefile

@@ -0,0 +1,31 @@
+NASM=nasm
+LD=ld
+COMPILE_32=elf
+
+# LD often has several different linking modes.  This sets the mode
+# explicitly, but if you're running on 32-bit Linux LD will use this
+# mode by default and the '-m' argument is unnecessary.
+LINK_32=elf_i386
+
+default: help
+
+all: hello strlen subroutines  ## Build everything at once
+
+%.o: %.s
+	$(NASM) -f $(COMPILE_32) $<
+
+hello: hello.o   ## Build Lesson 2: Print string with known length, exit cleanly
+	$(LD) -m $(LINK_32) -o $@ $<
+
+strlen: strlen.o  ## Build Lesson 2: Determine length programmatically
+	$(LD) -m $(LINK_32) -o $@ $<
+
+subroutines: subroutines.o  ## Build Lesson 3: Separate strlen() and puts() into subroutine.
+	$(LD) -m $(LINK_32) -o $@ $<
+
+help: run-help   ## Print this helpful message (default)
+
+clean:
+	rm -f hello strlen subroutines *.o
+
+include ../makefiles/help.make

x86_64/Makefile

@@ -0,0 +1,32 @@
+NASM=nasm
+LD=ld
+COMPILE_64=elf64
+
+# LD often has several different linking modes.  This sets the mode
+# explicitly, but if you're running on 64-bit Linux LD will use this
+# mode by default and the '-m' argument is unnecessary.
+LINK_64=elf_x86_64
+
+default: help
+
+all: hello strlen subroutines  ## Build everything at once
+
+%.o: %.s
+	$(NASM) -f $(COMPILE_64) $<
+
+hello: hello.o   ## Build Lesson 2: Print string with known length, exit cleanly
+	$(LD) -m $(LINK_64) -o $@ $<
+
+strlen: strlen.o  ## Build Lesson 2: Determine length programmatically
+	$(LD) -m $(LINK_64) -o $@ $<
+
+subroutines: subroutines.o  ## Build Lesson 3: Separate strlen() and puts() into subroutine.
+	$(LD) -m $(LINK_64) -o $@ $<
+
+help: run-help   ## Print this helpful message (default)
+
+clean:
+	rm -f hello strlen subroutines *.o
+
+include ../makefiles/help.make
+