diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..c5d275f
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,12 @@
+all:
+	cd xa-pre-process ; make ; cd ..
+	cd common ; make ; cd ..
+	cd emulator ; make ; cd ..
+
+run:
+	./emulator/emulator < common/system.obj
+
+clean:
+	cd xa-pre-process ; make clean ; cd ..
+	cd common ; make clean ; cd ..
+	cd emulator ; make clean ; cd ..
diff --git a/README.md b/README.md
index 256a5f6..df24cdc 100644
--- a/README.md
+++ b/README.md
@@ -1,10 +1,46 @@
 # COMMON
-Advances some ideas using Steve Wozniak's SWEET16 interpreted byte-code language as inspiration. While the goal of SWEET16 was brevity, the goal of COMMON is functionality.
+
+Advances some ideas using Steve Wozniak’s 6502 SWEET16 interpreted byte-code language as inspiration. While the goal of SWEET16 was brevity, the goal of COMMON is functionality. The intent is to make a platform suitable for many commercial, scientific, and engineering applications.
+
+For example:
+
+* native type is equivalent to fixed decimal ######.###
+* easier support for banked memory
+* easier support for higher language compilers
+* arithmetic operations add, subtract, multiply, divide, and modulus
+* inherent overflow/underflow detection
+* all control branching is 16-bit relative, for easier relocatable code
+* support for custom functions, akin to INT in x86
+
+Why 6502 and not, for example, x86?
+
+* 6502 assembler is very easy and has a large archive of existing functions
+* existing 6502 SWEET16 already has the “hard work” done
+* interesting to see it run in newer versions of 6502 processors
+* how do you think Bender does what he does? (or the Terminator!)
+
+In progress:
+
+* add all the instructions (see `common/common.h` for the list)
+* a simple unit test suite to ensure each instruction is correct
+
+The meat of the project:
+
+* `common/common.h`: details of instructions
+* `common/common.asm`: assembler code for the instructions
+* `common/macros.h`: macros used to define the interpreted byte-code
+* `common/page6.src`: sample source file using the macros
+
+Auxiliary:
+
+* `emulator/*`: 6502 emulator (borrowed Mike Chambers’ Fake6502 CPU emulator v1.1 ©2011)
+* `xa-pre-process/*`: utility `xapp` to convert 32-bit fixed decimal quantities so that `xa` can use them
+
+Right now, for testing purposes, the code builds everything into one file `system.obj` and runs the code in the last block loaded, in this case, the code corresponding to `page6.src`. Eventually will support decoupling of system and application files. Application files will be inherently relocatable.
 
 To build and run:
 
-    cd common-post-process ; make ; cp common-post-process ../common ; cd ..
-    cd common ; make ; cd ..
-    cd emulator ; make ; ./emulator < ../common/system.obj
+    make
+    make run
 
-The makefiles use `re2c`, `flex`, `bison`, `gcc`, `cpp`, and `xa`.
+The makefiles use `re2c`, `flex`, `bison`, `gcc`, `cpp`, and `xa`. Will eventually support a `make install` which will install all of these.
diff --git a/common/Makefile b/common/Makefile
index 0265c97..fe478a7 100644
--- a/common/Makefile
+++ b/common/Makefile
@@ -1,3 +1,5 @@
+XAPP=../xa-pre-process/xapp
+
 system.obj: common.obj page6.obj
 	cat common.obj page6.obj > system.obj
 
@@ -5,8 +7,8 @@ common.obj: rom.h common.h common.asm
 	xa -M common.asm -l common.lbl -o common.obj
 
 page6.obj: rom.h macros.h page6.src
-	cpp -P page6.src | ./common-post-process > page6.asm
+	cpp -P page6.src | $(XAPP) > page6.asm
 	xa -M page6.asm -l page6.lbl -o page6.obj
 
 clean: 
-	rm -f page6.asm common.obj page6.obj common.lbl page6.lbl
+	rm -f page6.asm common.obj page6.obj common.lbl page6.lbl system.obj
diff --git a/common/common.h b/common/common.h
index d731c1f..1748c7d 100644
--- a/common/common.h
+++ b/common/common.h
@@ -1,7 +1,10 @@
 #ifndef __COMMON_H
 #define __COMMON_H
 
-; Using four byte quantities aabbccdd with one bit overflow/underflow, 21 bits significand, 10 bits fraction
+; Using four byte quantities aabbccdd with sign bit, overflow/underflow bit, 20 bits significand, 10 bits
+; fraction. The quantity is valid if the overflow/underflow bit agrees with the sign bit. The intent is
+; to be able to recognize an overflow/underflow situation, rescale the arguments, and repeat the
+; calculation.
 
 ; Largest value:          $3fffffff or  1048575.999(9)
 ; Smallest value:         $c0000001 or -1048575.999(0)
@@ -132,8 +135,8 @@ _EXT_C	= $f0
 _PLS_1	= %00000100	; i.e. the $04 part of $00000400
 _MNS_1	= %11111100	; i.e. the $FC part of $FFFFFC00
 
-; masks for overflow and unerflow
+; masks for overflow and underflow
 _MSK_O	= %11000000	; mask for overflow
-_MSK_U	= %11000000	; mask for underflow
+_MSK_U	= %11000000	; mask for underflow - yes, the same!
 
 #endif /* __COMMON_H */
diff --git a/emulator/Makefile b/emulator/Makefile
index 31794fe..3955245 100644
--- a/emulator/Makefile
+++ b/emulator/Makefile
@@ -1,3 +1,6 @@
 emulator: emulator.h emulator.c main.c
 	gcc -o emulator emulator.c main.c
 
+clean:
+	rm -f emulator
+
diff --git a/common-post-process/Makefile b/xa-pre-process/Makefile
similarity index 91%
rename from common-post-process/Makefile
rename to xa-pre-process/Makefile
index 9e70c7f..6b199fa 100644
--- a/common-post-process/Makefile
+++ b/xa-pre-process/Makefile
@@ -1,4 +1,4 @@
-TGT=common-post-process
+TGT=xapp
 
 $(TGT): main.c $(TGT).h $(TGT).re $(TGT).l $(TGT).y
 	re2c -is $(TGT).re -o $(TGT).c
@@ -7,4 +7,4 @@ $(TGT): main.c $(TGT).h $(TGT).re $(TGT).l $(TGT).y
 	gcc main.c $(TGT).c $(TGT).tab.c $(TGT).yy.c -lfl -lm -o $(TGT)
 
 clean: 
-	rm -f $(TGT).c $(TGT).yy.h $(TGT).yy.c $(TGT).tab.h $(TGT).tab.c
+	rm -f $(TGT).c $(TGT).yy.h $(TGT).yy.c $(TGT).tab.h $(TGT).tab.c $(TGT)
diff --git a/common-post-process/main.c b/xa-pre-process/main.c
similarity index 94%
rename from common-post-process/main.c
rename to xa-pre-process/main.c
index 604ff4b..7e2609b 100644
--- a/common-post-process/main.c
+++ b/xa-pre-process/main.c
@@ -2,8 +2,8 @@
 #include <limits.h>
 #include <string.h>
 
-#include "common-post-process.h"
-#include "common-post-process.yy.h"
+#include "xapp.h"
+#include "xapp.yy.h"
 
 long long result;
 
diff --git a/common-post-process/common-post-process.h b/xa-pre-process/xapp.h
similarity index 93%
rename from common-post-process/common-post-process.h
rename to xa-pre-process/xapp.h
index a369e5a..4c6eebf 100644
--- a/common-post-process/common-post-process.h
+++ b/xa-pre-process/xapp.h
@@ -1,5 +1,5 @@
-#ifndef __COMMON_POST_PROCESS_H
-#define __COMMON_POST_PROCESS_H
+#ifndef __XAPP_H
+#define __XAPP_H
 
 /* How many bits for ... */
 
@@ -68,4 +68,4 @@ int tokenizeInput(const char *cursor, TOKEN *tokens);
 long long parseCommon(const char *input);
 long long shiftCommon(long long base, long long amount);
 
-#endif /* __COMMON_POST_PROCESS_H */
\ No newline at end of file
+#endif /* __XAPP_H */
\ No newline at end of file
diff --git a/common-post-process/common-post-process.l b/xa-pre-process/xapp.l
similarity index 95%
rename from common-post-process/common-post-process.l
rename to xa-pre-process/xapp.l
index 4b3931f..1713435 100644
--- a/common-post-process/common-post-process.l
+++ b/xa-pre-process/xapp.l
@@ -3,7 +3,7 @@
 #include <stdio.h>
 #include <string.h>
 
-#include "common-post-process.tab.h"
+#include "xapp.tab.h"
 
 %}
 
diff --git a/common-post-process/common-post-process.re b/xa-pre-process/xapp.re
similarity index 98%
rename from common-post-process/common-post-process.re
rename to xa-pre-process/xapp.re
index a91f5d3..ebe2718 100644
--- a/common-post-process/common-post-process.re
+++ b/xa-pre-process/xapp.re
@@ -1,7 +1,7 @@
 #include <stdio.h>
 #include <string.h>
 
-#include "common-post-process.h"
+#include "xapp.h"
 
 static int copyToken(TOKEN *tokens, int index, TOKEN_TYPE type, const char *text, int length);
 
diff --git a/common-post-process/common-post-process.y b/xa-pre-process/xapp.y
similarity index 97%
rename from common-post-process/common-post-process.y
rename to xa-pre-process/xapp.y
index dea0305..1977893 100644
--- a/common-post-process/common-post-process.y
+++ b/xa-pre-process/xapp.y
@@ -1,7 +1,7 @@
 %error-verbose
 
 %code requires {
-	#include "common-post-process.h"
+	#include "xapp.h"
 }
 
 %{
@@ -10,8 +10,8 @@
 	#include <limits.h>
 	#include <math.h>
 
-	#include "common-post-process.h"
-	#include "common-post-process.yy.h"
+	#include "xapp.h"
+	#include "xapp.yy.h"
 %}
 
 %union {