diff --git a/Readme.unix b/Readme.unix
index fcc12ca3..710487c6 100644
--- a/Readme.unix
+++ b/Readme.unix
@@ -1,7 +1,49 @@
-prerequisites:
+this tree now contains makefiles and tools to build on Linux and MacosX
+Linux is rather more thoroughly tested compared to os-x.
 
-gcc
-yacc
-make
-g++
+to get here, TASM and the propeller generation tools needed to be replaced,
+and since the unix filesystem is usually case-sensitive, and CP/M and windows
+are not, the cpm tools were made case-insensitive.
 
+TASM was replaced with uz80as, which implements a subset of TASM and fixes some
+bugs.  however, I needed to add some functionality to make it build the sources
+as they exist in this tree.   in particular, one thing to be very careful of is
+that TASM is not entirely consistent with respect to the .DS directive.
+it's usually a bad idea to mix .DS, .FILL, .DB with .ORG.  
+	.DS n is best thought of as .ORG $ + n
+	.ORG changes the memory pointer, but does not change the file output point.
+		it works a lot more like M80, SLR* .phase
+
+it assumes that you have some standard system tools and libraries installed
+specifically: gcc, gnu make, libncurses
+
+to build:
+	cd to the top directory and type make.
+
+heavy use is made of make's include facility and pattern rules.
+the master rule set is in Tools/Makefile.inc.  changes here will affect
+almost every Makefile, and where exceptions are needed, the overrides are
+applied in the lower Makefiles.
+
+these tools can run a windows-linux regression test, where all the binaries are
+compared to a baseline windows build.
+
+Credit:
+
+	uz80as was written by Jorge Giner Cordero, jorge.giner@hotmail.com,
+	and the original source can be found at https://github.com/jorgicor/uz80as
+
+	the propeller tools use bstc and openspin, parallax tools from 
+	http://www.fnarfbargle.com/bst.html https://github.com/parallaxinc/OpenSpin
+	note that bst is not open source or even currently maintained, so I could 
+	not generate a version for 64 bit osx.
+
+	cpmtools were the most current I could find, and it has been hacked to do
+	case-insensitivity. these are not marked, and are not extensive.
+
+	zx is from distributed version, and also has local hacks for case insensitivity.
+	both zx and cpmtools ship with an overly complicated makefile generation system
+	and this is ignored.
+
+	this whole linux build framework is the work of Curt Mayer, curt@zen-room.org.
+	use it for whatever you like; this is not my day job.