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+abCalc
+======
+
+The "Ass-Backward Calculator" for the Apple //GS - an RPN calculator NDA
+
+The source can be built both from Mac OSX, resulting in a commandline binary which you can run on a Mac and from a //GS.
+To build and execute on a Mac:
+
+1. Make sure you have Xcode installed.  If not, grab it from the Mac App store.
+2. Execute "make -f Make.mac"
+3. Run "./abCalc"
+
+In theory, it should work on any POSIX platform like Linux, Solaris, etc but I have not tested it on any other platforms.
+
+To build this on a //GS, you need a number of prerequisites:
+
+1. Orca/C v2.0.1
+2. GNO/ME v2.x
+3. occ - the Orca/C wrapper
+4. dmake
+
+To build this on a //GS, the steps are:
+
+1. Somehow copy the files to your //GS.  Depending on whether you are using a real machine or an emulator, your
+approach here may be different.
+2. Find this line in your ORCACDefs/scrap.h file:
+    extern pascal void PutScrap(unsigned Longint, Word, Pointer) inline(0x0C16,dispatcher);
+and change it to
+    extern pascal void PutScrap(LongWord, Word, Pointer) inline(0x0C16,dispatcher);
+This is a bug in the headers which causes ORCA/C to generate the wrong output.
+3. Once you have the files, you should first execute "dmake fixfiles".  This makes sure all files have the right
+file types.
+4. Execute "dmake"
+
+When done, you will have two binaries.  The abCalc binary is a shell command you can use from GNO/ME:
+
+![abCalc Shell Screenshot](/screenshots/abCalc.png "abCalc Shell Screenshot")
+
+And abCalcNDA is a new desk accessory which you can use from within GS/OS applications:
+
+![abCalc NDA Screenshot](/screenshots/abCalcNDA.png "abCalc NDA Screenshot")