Add a compiling option to remove speed limitations

emulator.pas

@@ -15,8 +15,7 @@ type
 {$endif}
 
 const
-    IO = $ffff;
-    LastRAM = $ffef;
+    LastRAM = $ffef; //The last address of RAM
 
 var
     Hlt, ASCII, Verbose: boolean; //Halt, ASCII, and verbose flags
@@ -55,12 +54,14 @@ begin
 end;
 
 //Wait to emulate CPU speed of ~500 KIPS
+{$ifndef fast}
 procedure wait;
 begin
     if IC div 500 = 0 then sleep (1)
     else sleep (IC div 500);
     IC := 0;
 end;
+{$endif}
 
 //Load a byte from memory
 function LoadByte (W: word): byte;
@@ -68,8 +69,10 @@ var
     B: byte;
 begin
     //Terminal input
-    if W = IO then begin
+    if W = $ffff then begin
+        {$ifndef fast}
         wait;
+        {$endif}
         //Read a keypress
         repeat
         Ch := ReadKey;
@@ -116,7 +119,9 @@ begin
     //Tape reader
     {$ifdef tape}
     else if W = $fffd then begin
+        {$ifndef fast}
         wait;
+        {$endif}
         assign (State, ExpandFileName ('~/.tapes.thingamajig'));
         //Check the reader state
         if FileExists (ExpandFileName ('~/.tapes.thingamajig')) then begin
@@ -162,15 +167,19 @@ end;
 procedure StoreByte (W: word; B: byte);
 begin
     //Terminal output
-    if W = IO then begin
+    if W = $ffff then begin
+        {$ifndef fast}
         wait;
+        {$endif}
         Ch := ansichar (B);
         Output;
     end
     //Printer
     {$ifdef printer}
     else if W = $fffe then begin
+        {$ifndef fast}
         wait;
+        {$endif}
         assign (Prn, '/dev/usb/lp0');
         try
             rewrite (Prn);
@@ -183,7 +192,9 @@ begin
     //Tape punch
     {$ifdef tape}
     else if W = $fffd then begin
+        {$ifndef fast}
         wait;
+        {$endif}
         assign (State, ExpandFileName ('~/.tapes.thingamajig'));
         //Check the punch state
         if FileExists (ExpandFileName ('~/.tapes.thingamajig')) then begin
@@ -413,6 +424,8 @@ begin
 
     end;
 
+    {$ifndef fast}
     wait;
+    {$endif}
 
 end.

readme.md

@@ -92,14 +92,16 @@ uninitialised.
 Emulator
 --------
 
-The emulator runs at roughly 500 KIPS and has the full 65520 bytes of
-RAM.
+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.
 
-Input and output are handled by an emulated roughly 1000 CPS glass
-teletype terminal with local echo. Note that of the control characters
-only bell, backspace, line feed, and carriage return are used by the
-terminal, and the backspace and delete keys are tied to their respective
-characters and non-character keys to null.
+Input and output are handled by an emulated glass teletype terminal with
+local echo. Note that of the control characters only bell, backspace,
+line feed, and carriage return are used by the terminal, and the
+backspace and delete keys are tied to their respective characters and
+non-character keys to null.
 
 In Linux the emulator can be compiled with support for a character
 printer and an emulated punched tape reader and punch with the arguments