Add options to compile the emulator with specific amounts of memory

emulator.pas

@@ -15,7 +15,20 @@ type
 {$endif}
 
 const
-    LastRAM = $ffef; //The last address of RAM
+    //The last address of RAM
+    {$if defined(RAM4)}
+    LastRAM = $fff; //4 KiB
+    {$elseif defined(RAM8)}
+    LastRAM = $1fff; //8 KiB
+    {$elseif defined(RAM16)}
+    LastRAM = $3fff; //16 KiB
+    {$elseif defined(RAM32)}
+    LastRAM = $7fff; //32 KiB
+    {$elseif defined(RAM64)}
+    LastRAM = $ffef; //64 KiB
+    {$else}
+    LastRAM = $7ff; //2 KiB (default)
+    {$endif}
 
 var
     Hlt, ASCII, Verbose: boolean; //Halt, ASCII, and verbose flags

readme.md

@@ -92,10 +92,12 @@ uninitialised.
 Emulator
 --------
 
-The emulator runs at roughly 500 KIPS, has the full 65520 bytes of RAM,
-and interacts with memory mapped devices at roughly 1000 CPS. The speed
-limitations can be removed by compiling the emulator with the argument
--dfast.
+By default the emulator runs at roughly 500 KIPS, has 2 KiB of RAM, and
+interacts with memory mapped devices at roughly 1000 CPS. The arguments
+-dRAM4, -dRAM8, -dRAM16, -dRAM32, and -dRAM64 can be used to compile
+the emulator with 4, 8, 16, 32, or 64 KiB (minus the reserved addresses)
+of RAM respectively instead and the speed limitations can be removed
+with the argument -dfast.
 
 Input and output are handled by an emulated glass teletype terminal with
 local echo. Note that of the control characters only bell, backspace,