-------------------------------------------------------------------------------
-- Mystic Marathon by Dar (darfpga@aol.fr) (05 March 2022)
-- http://darfpga.blogspot.fr
-- https://sourceforge.net/projects/darfpga/files
-- github.com/darfpga
--
--  Terasic board MAX10 DE10 Lite
-------------------------------------------------------------------------------
-- gen_ram.vhd & io_ps2_keyboard
-------------------------------- 
-- Copyright 2005-2008 by Peter Wendrich (pwsoft@syntiac.com)
-- http://www.syntiac.com/fpga64.html
-------------------------------------------------------------------------------
-- cpu09l - Version : 0128
-- Synthesizable 6809 instruction compatible VHDL CPU core
-- Copyright (C) 2003 - 2010 John Kent
-------------------------------------------------------------------------------
-- cpu68 - Version 9th Jan 2004 0.8
-- 6800/01 compatible CPU core 
-- GNU public license - December 2002 : John E. Kent
-------------------------------------------------------------------------------
-- Educational use only
-- Do not redistribute synthetized file with roms
-- Do not redistribute roms whatever the form
-- Use at your own risk
-------------------------------------------------------------------------------
--  Video 15KHz is OK, 
--
--  This is not VGA, you have to use a TV set with SCART plug
--
--    SCART(TV) pin  - signal -  VGA(DE10) pin
--               15  -  red   -  1          
--               11  - green  -  2
--                7  -  blue  -  3  
--           5,9,13  -  gnd   -  5,6,7
--   (comp. sync)20  - csync  -  13 (HS)   
--  (fast commut)16  - commut -  14 (VS)
--            17,18  -  gnd   -  8,10 
--
-------------------------------------------------------------------------------
-- Version 0.0 -- 18/03/2022 -- 
--	initial version 
-------------------------------------------------------------------------------
--
-- Main features :
--  PS2 keyboard input @gpio pins 35/34 (beware voltage translation/protection)
--  Audio pwm output   @gpio pins 1/3 (beware voltage translation/protection)
--
-- Uses 1 pll for 12MHz and 120MHz generation from 50MHz
--
-- Board key :
--   0 : reset game
--
-- Keyboard players inputs :
--
--   F3 : Add coin
--   F2 : Start 2 players
--   F1 : Start 1 player
--   SPACE       : Fire  
--   RIGHT arrow : Move right
--   LEFT  arrow : Move left
--   UP    arrow : Move up 
--   DOWN  arrow : Move down
--   CTRL        : N.U.
--   W(Z)        : N.U.
--
-- Keyboard Service inputs French(english) :
--
--   A(Q) : advance
--   U(U) : auto/up (!manual/down)
--   H(H) : high score reset
--
-- To enter service mode press 'advance' key while in game over screen
-- Enter service mode to tune game parameters (difficulty ...)
-- Tuning are lost at power OFF, for permanent tuning edit/set parameters
--   within mystic_marathon_cmos_ram.vhd and recompile.
--
-------------------------------------------------------------------------------
-- Use make_mystic_marathon_proms.bat to build vhd file and bin from binaries
-- Load sdram with external rom bank -> use sdram_loader_de10_lite.sof + key(0)
-------------------------------------------------------------------------------
-- Program sdram content with this Mystic Marathon rom bank loader before 
-- programming Mystic Marathon game core :
--
-- 1) program DE10_lite with Mystic Marathon sdram loader
-- 2) press key(0) at least once (digit blinks during programming)
-- 3) program DE10_lite with Mystic Marathon core without switching DE10_lite OFF
-------------------------------------------------------------------------------
-- Used ROMs by make_mystic_marathon_proms.bat

> mystic_marathon_prog2
   mm02_2.a09 CRC(3a776ea8) IC9 
   mm03_2.a10 CRC(6e247c75) IC10

> mystic_marathon_bank_a
   mm18_1.a26 CRC(9b391a81) IC26
   mm16_1.a24 CRC(399e175d) IC24
   mm14_1.a22 CRC(191153b1) IC22

> mystic_marathon_bank_b
   mm17_1.a25 CRC(d36f0a96) IC25
   mm15_1.a23 CRC(cd5d99da) IC23
   mm13_1.a21 CRC(ef4b79db) IC21
   mm12_1.a19 CRC(a1f04bf0) IC19

> mystic_marathon_bank_c
   mm11_1.a18 CRC(f537968e) IC18
   mm09_1.a16 CRC(3bd12f6c) IC16
   mm07_1.a14 CRC(ea2a2a68) IC14
   mm05_1.a12 CRC(b514eef3) IC12

> mystic_marathon_bank_d
   mm10_1.a17 CRC(d6a37509) IC17
   mm08_1.a15 CRC(6f1a64f2) IC15
   mm06_1.a13 CRC(2e6795d4) IC13
   mm04_1.a11 CRC(c222fb64) IC11

> mystic_marathon_sound
   mm01_1.a08 CRC(65339512) IC8 

> mystic_marathon_graph1
   mm20_1.b57 CRC(5c0f4f46) IC57

> mystic_marathon_graph2
   mm21_1.b58 CRC(cb90b3c5) IC58

> mystic_marathon_graph3
   mm19_1.b41 CRC(e274df86) IC41

> mystic_marathon_decoder
   ic60.bpr CRC(0ea3f7fb) IC60

-------------------------------------------------------------------------------
-- Misc. info
-------------------------------------------------------------------------------
-- Main bus access
--  > Main address bus and data bus by CPU 6809
--  > Main address bus and data bus by DMA (blitter) while CPU is halted.
--
-- CPU and DMA can read/write anywhere from/to entire 64K address space
-- including video ram, color palette, tile map, cmos_ram, peripherals, roms,
-- switched rom banks, ...

--
-- Page register control allows to select misc. banked access (rom, ram). 
-------------------------------------------------------------------------------
-- Video ram : 3 banks of 16Kx8 (dram with ras/cas)
--  > interleaved bank access by CPU, 8bits read/write
--  > interleaved bank access by DMA, 8bits read, 2x4bits independent write
--  > simultaneous (3 banks) access by video scanner, 24bits at once
-- 
-- In original hardware, every 1us there is 1 access to video ram for CPU/DMA
-- and 1 access for video scanner. Thus DMA read/write cycle required 2us when
-- reading source is video ram. DMA read/write cycle required only 1us when
-- reading source is not video ram.
--
-- Higher part of video ram is not displayed on screen and is used as working
-- ram by CPU including stack (SP).
-------------------------------------------------------------------------------
-- Foreground (bitmap - video ram)
--  > 24 bits / 1us => 6 horizontal pixels of 4bits (16 colors)
--  > 6 bits register (64 color banks)
-------------------------------------------------------------------------------
-- Background (tile map : tile is 24x16 pixels)
--
--  > 16 horizontal tiles of 4x6 pixels, 16 vertical tiles of 16 pixels.
--  > map ram 2048x8
--      in  : 7 bits horizontal (4 bits + scroll) + 4 bits vertical
--      out : 128 possible tiles + flip control
--
--  > Graphics 3x8Kx8 roms
--      in  : 2 bits horizontal + 4 bits vertical + 7 bits tile code 
--      out : 24 bits = 6 pixels x 4 bits
--
--  > 24 bits / 1us => 6 horizontal pixels of 4bits (16 colors)
--  > 5 bits register + 1 bits from vertical video scanner (64 color banks)
-------------------------------------------------------------------------------
-- Palette 1024 colors x 16 bits
--  > in  10 bits from foreground or background data
--  > out 4 bits red, 4 bits green, 4 bits blue, 4 bits intensity 
-------------------------------------------------------------------------------