Started work on the controller side of the CompuMate emulation.

git-svn-id: svn://svn.code.sf.net/p/stella/code/trunk@2411 8b62c5a3-ac7e-4cc8-8f21-d9a121418aba

src/emucore/CartCM.hxx

@@ -98,6 +98,11 @@ class System;
   by two 20K resistors, then it goes through a hex inverting schmitt trigger to
   square it up.  This then runs into bit 7 of portA.
 
+  This code was heavily borrowed from z26, and uses conventions defined
+  there.  Specifically, IOPortA is treated as a complete uInt8, whereas
+  the Stella core actually stores this information in boolean arrays
+  addressable by DigitalPin number.
+
   @author  Stephen Anthony & z26 team
   @version $Id$
 */

src/emucore/CompuMate.hxx

@@ -25,46 +25,77 @@
 #include "Event.hxx"
 
 /**
-  The Spectravideo CompuMate SV010 was a home computer expansion for the
+  Cartridge class used for SpectraVideo CompuMate bankswitched games.
-  Atari VCS / 2600 video game system.
 
-  It consists of a membrane keyboard unit with interface connectors. These
+  This is more than just a cartridge mapper - it's also a "computer" add-on.  
-  connectors were placed in the module slot and both controller ports of the
+  There's two 8K EPROMs soldered on top of each other.  There's two short
-  Atari console.  As the user could place the keyboard on the old style VCS
+  wires with DB-9's on them which you plug into the two controller ports.
-  consoles, the two devices resulted in one compact unit. When using with the
+  A 42 or so key membrane keyboard with audio in and audio out, and 2K of RAM.
-  2600jr console, resulted in a desktop computer look with separated keyboard.
 
-  The CompuMate was equipped with an audio jack for use with a standard tape
+  There are 4 4K banks selectable at $1000 - $1FFF, and 2K RAM at
-  connector as a possibility of permanent data storage.
+  $1800 - $1FFF (R/W 'line' is available at SWCHA D5, so there's no separate
+  read and write ports).
 
   Bankswitching is done though the controller ports
-    INPT0: D7 = CTRL key input (0 on startup / 1 = key pressed)
+    SWCHA: D7 = Audio input from tape player
-    INPT1: D7 = always HIGH input (tested at startup)
+           D6 = Audio out to tape player and 4017 CLK
-    INPT2: D7 = always HIGH input (tested at startup)
+                1 -> increase key column (0 to 9)
-    INPT3: D7 = SHIFT key input (0 on startup / 1 = key pressed)
+           D5 = 4017 RST, and RAM direction. (high = write, low = read)
-    INPT4: D7 = keyboard row 1 input (0 = key pressed)
+                1 -> reset key column to 0 (if D4 = 0)
-    INPT5: D7 = keyboard row 3 input (0 = key pressed)
+                0 -> enable RAM writing (if D4 = 1)
-    SWCHA: D7 = tape recorder I/O ?
+           D4 = RAM enable: 1 = disable RAM, 0 = enable RAM
-           D6 = 1 -> increase key collumn (0 to 9)
+           D3 = keyboard row 1 input (0 = key pressed)
-           D5 = 1 -> reset key collumn to 0 (if D4 = 0)
+           D2 = keyboard row 1 input (0 = key pressed)
-           D5 = 0 -> enable RAM writing (if D4 = 1)
-           D4 = 1 -> map 2K of RAM at $1800 - $1fff
-           D3 = keyboard row 4 input (0 = key pressed)
-           D2 = keyboard row 2 input (0 = key pressed)
            D1 = bank select high bit
            D0 = bank select low bit
 
-  Keyboard column numbering:
+    INPT0: D7 = CTRL key input (0 on startup / 1 = key pressed)
-    column 0 = 7 U J M
+    INPT1: D7 = always HIGH input (pulled high thru 20K resistor)
-    column 1 = 6 Y H N
+    INPT2: D7 = always HIGH input (pulled high thru 20K resistor)
-    column 2 = 8 I K ,
+    INPT3: D7 = SHIFT key input (0 on startup / 1 = key pressed)
-    column 3 = 2 W S X
+    INPT4: D7 = keyboard row 0 input (0 = key pressed)
-    column 4 = 3 E D C
+    INPT5: D7 = keyboard row 2 input (0 = key pressed)
-    column 5 = 0 P ENTER SPACE
+
-    column 6 = 9 O L .
+  The keyboard's composed of a 4017 1 of 10 counter, driving the 10 columns of
-    column 7 = 5 T G B
+  the keyboard.  It has 4 rows.  The 4 row outputs are buffered by inverters.
-    column 8 = 1 Q A Z
+
-    column 9 = 4 R F V
+  Bit 5 of portA controls the reset line on the 4017.  Pulling it high will reset
+  scanning to column 0.  Pulling it low will allow the counter to be clocked.
+
+  Bit 6 of portA clocks the 4017.  Each rising edge advances the column one
+  count.
+
+  There's 10 columns labelled 0-9, and 4 rows, labelled 0-3.
+
+                           Column
+
+    0     1     2     3     4     5     6     7     8     9
+  +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+
+  | 7 | | 6 | | 8 | | 2 | | 3 | | 0 | | 9 | | 5 | | 1 | | 4 |  0
+  +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ 
+  +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ 
+  | U | | Y | | I | | W | | E | | P | | O | | T | | Q | | R |  1
+  +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+     Row
+  +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+
+  | J | | H | | K | | S | | D | |ent| | L | | G | | A | | F |  2
+  +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ 
+  +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+
+  | M | | N | | < | | X | | C | |spc| | > | | B | | Z | | V |  3
+  +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ 
+
+  Function and Shift are separate keys that are read by 2 of the paddle inputs.
+  These two buttons pull the specific paddle input low when pressed.
+
+  Because the inputs are inverted, a low indicates a pressed button, and a high 
+  is an unpressed one.
+
+  The audio input/output are designed to drive a tape player.  The audio output is 
+  buffered through an inverter and 2 resistors and a capacitor to reduce the level
+  to feed it into the tape player.
+
+  The audio input is passed through a .1uf capacitor and is pulled to 1/2 supply
+  by two 20K resistors, then it goes through a hex inverting schmitt trigger to
+  square it up.  This then runs into bit 7 of portA.
 
   This code was heavily borrowed from z26, and uses conventions defined
   there.  Specifically, IOPortA is treated as a complete uInt8, whereas