Update README file with memory map.

hdl/spec/syn/README

@@ -6,9 +6,23 @@ files section of the project:
 http://www.ohwr.org/projects/gn4124-core/files
 
 Procedure to generate the gateware binary:
+$ cd <gn4124 core dir>/hdl/spec/syn/
+$ hdlmake -f
+$ hdlmake --ise-proj
+$ hdlmake --make-ise
+$ make
 
-cd <gn4124 core dir>/hdl/spec/syn/
-hdlmake -f
-hdlmake --ise-proj
-hdlmake --make-ise
-make
\ No newline at end of file
+Memory map:
+
+0x00000 : GN4124 DMA configuration registers
+          -> See GN4124 doc for register mapping.
+0x40000 : Status registers
+      0 : 0xDEADBABE
+      4 : 0xBEEFFACE
+      8 : 0x12345678
+      C : Bit 0 = P2L PLL lock status (1=pll locked)
+0x80000 : Control regiters
+      0 : Not connected internally, can be used to perform r/w
+      4 : Not connected internally, can be used to perform r/w
+      8 : Not connected internally, can be used to perform r/w
+      C : Bits 0 and 1 connected to SPEC front-panel LEDs (1=LED ON)
\ No newline at end of file