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[/] [System09/] [trunk/] [rtl/] [System09_Digilent_3S500E/] [System09_Digilent_3S500E.vhd] - Blame information for rev 114

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Line No. Rev Author Line
1 109 davidgb 
-- $Id: System09_Digilent_3S500E.vhd,v 1.3.2.1 2008/04/08 14:59:48 davidgb Exp $
2 19 dilbert57 
--===========================================================================----
3 
--
4 
--  S Y N T H E Z I A B L E    System09 - SOC.
5 
--
6 109 davidgb 
--===========================================================================----
7 
--
8 19 dilbert57 
--  This core adheres to the GNU public license
9 
--
10 109 davidgb 
-- File name      : System09_Digilent_3S500E.vhd
11 19 dilbert57 
--
12 
-- Purpose        : Top level file for 6809 compatible system on a chip
13 
--                  Designed with Xilinx XC3S500E Spartan 3E FPGA.
14 
--                  Implemented With Digilent Xilinx Starter FPGA board,
15 
--
16 
-- Dependencies   : ieee.Std_Logic_1164
17 
--                  ieee.std_logic_unsigned
18 
--                  ieee.std_logic_arith
19 
--                  ieee.numeric_std
20 
--
21 109 davidgb 
-- Uses           : mon_rom  (kbug_rom2k.vhd) Monitor ROM
22 19 dilbert57 
--                  cpu09    (cpu09.vhd)      CPU core
23 
--                  miniuart (minitUART3.vhd) ACIA / MiniUART
24 
--                           (rxunit3.vhd)
25 
--                           (tx_unit3.vhd)
26 
--
27 
-- Author         : John E. Kent
28 
--                  dilbert57@opencores.org
29 
--
30 
--===========================================================================----
31 
--
32 
-- Revision History:
33 
--===========================================================================--
34 
-- Version 0.1 - 20 March 2003
35 
-- Version 0.2 - 30 March 2003
36 
-- Version 0.3 - 29 April 2003
37 
-- Version 0.4 - 29 June 2003
38 
--
39 
-- Version 0.5 - 19 July 2003
40 
-- prints out "Hello World"
41 
--
42 
-- Version 0.6 - 5 September 2003
43 
-- Runs SBUG
44 
--
45 
-- Version 1.0- 6 Sep 2003 - John Kent
46 
-- Inverted CLK_50MHZ
47 
-- Initial release to Open Cores
48 
--
49 
-- Version 1.1 - 17 Jan 2004 - John Kent
50 
-- Updated miniUart.
51 
--
52 
-- Version 1.2 - 25 Jan 2004 - John Kent
53 
-- removed signals "test_alu" and "test_cc"
54 
-- Trap hardware re-instated.
55 
--
56 
-- Version 1.3 - 11 Feb 2004 - John Kent
57 
-- Designed forked off to produce System09_VDU
58 
-- Added VDU component
59 
--      VDU runs at 25MHz and divides the clock by 2 for the CPU
60 
-- UART Runs at 57.6 Kbps
61 
--
62 
-- Version 2.0 - 2 September 2004 - John Kent
63 
-- ported to Digilent Xilinx Spartan3 starter board
64 
--      removed Compaact Flash and Trap Logic.
65 
-- Replaced SBUG with KBug9s
66 
--
67 
-- Version 3.0 - 22 April 2006 - John Kent
68 
-- Port to Digilent Spartan 3E Starter board
69 
-- Removed keyboard, vdu, timer, and trap logic
70 
-- added PIA with counters attached.
71 
-- Uses 32Kbytes of internal Block RAM
72 20 dilbert57 
--
73 
-- Version 4.0 - 8th April 2007 - John kent
74 
-- Added VDU and PS/2 keyboard
75 
-- Updated miniUART to ACIA6850
76 
-- Reduce monitor ROM to 2KB
77 
-- Re-assigned I/O port assignments so it is possible to run KBUG9
78 
-- $E000 - ACIA
79 
-- $E020 - Keyboard
80 
-- $E030 - VDU
81 
-- $E040 - Compact Flash (not implemented)
82 
-- $E050 - Timer
83 
-- $E060 - Bus trap
84 
-- $E070 - Parallel I/O
85 
--
86 19 dilbert57 
--===========================================================================--
87 
library ieee;
88 
   use ieee.std_logic_1164.all;
89 
   use IEEE.STD_LOGIC_ARITH.ALL;
90 
   use IEEE.STD_LOGIC_UNSIGNED.ALL;
91 
   use ieee.numeric_std.all;
92 
 
93 59 davidgb 
entity my_system09 is
94 19 dilbert57 
  port(
95 
    CLK_50MHZ     : in  Std_Logic;  -- System Clock input
96 
    BTN_SOUTH     : in  Std_Logic;
97 
 
98 20 dilbert57 
         -- PS/2 Keyboard
99 
         PS2_CLK      : inout Std_logic;
100 
         PS2_DATA     : inout Std_Logic;
101 
 
102 
         -- CRTC output signals
103 
         VGA_VSYNC     : out Std_Logic;
104 
    VGA_HSYNC     : out Std_Logic;
105 
    VGA_BLUE      : out std_logic;
106 
    VGA_GREEN     : out std_logic;
107 
    VGA_RED       : out std_logic;
108 
 
109 19 dilbert57 
         -- Uart Interface
110 
         RS232_DCE_RXD : in  std_logic;
111 
    RS232_DCE_TXD : out std_logic;
112 
 
113 
         -- LEDS & Switches
114 
         LED           : out std_logic_vector(7 downto 0)
115 
         );
116 59 davidgb 
end my_system09;
117 19 dilbert57 
 
118 
-------------------------------------------------------------------------------
119 
-- Architecture for System09
120 
-------------------------------------------------------------------------------
121 59 davidgb 
architecture my_computer of my_system09 is
122 19 dilbert57 
  -----------------------------------------------------------------------------
123 20 dilbert57 
  -- constants
124 
  -----------------------------------------------------------------------------
125 109 davidgb 
  constant SYS_CLK_FREQ  : integer := 50000000;  -- FPGA System Clock
126 
  constant VGA_CLK_FREQ  : integer := 25000000;  -- VGA Pixel Clock
127 
  constant CPU_CLK_FREQ  : integer := 25000000;  -- CPU Clock
128 
  constant BAUD_RATE     : integer := 57600;      -- Baud Rate
129 
  constant ACIA_CLK_FREQ : integer := BAUD_RATE * 16;
130 20 dilbert57 
 
131 
  -----------------------------------------------------------------------------
132 19 dilbert57 
  -- Signals
133 
  -----------------------------------------------------------------------------
134 
  -- BOOT ROM
135 20 dilbert57 
  signal rom_cs         : Std_logic;
136 
  signal rom_data_out   : Std_Logic_Vector(7 downto 0);
137 19 dilbert57 
 
138 
  -- UART Interface signals
139 20 dilbert57 
  signal uart_data_out  : Std_Logic_Vector(7 downto 0);
140 
  signal uart_cs        : Std_Logic;
141 
  signal uart_irq       : Std_Logic;
142 
  signal uart_clk       : Std_Logic;
143 
  signal rxbit          : Std_Logic;
144 
  signal txbit          : Std_Logic;
145 
  signal DCD_n          : Std_Logic;
146 
  signal RTS_n          : Std_Logic;
147 
  signal CTS_n          : Std_Logic;
148 19 dilbert57 
 
149 20 dilbert57 
  -- timer
150 
  signal timer_data_out : std_logic_vector(7 downto 0);
151 
  signal timer_cs       : std_logic;
152 
  signal timer_irq      : std_logic;
153 
 
154 
  -- trap
155 
  signal trap_cs        : std_logic;
156 
  signal trap_data_out  : std_logic_vector(7 downto 0);
157 
  signal trap_irq       : std_logic;
158 
 
159 19 dilbert57 
  -- PIA Interface signals
160 20 dilbert57 
  signal pia_data_out   : Std_Logic_Vector(7 downto 0);
161 
  signal pia_cs         : Std_Logic;
162 
  signal pia_irq_a      : Std_Logic;
163 
  signal pia_irq_b      : Std_Logic;
164 19 dilbert57 
 
165 20 dilbert57 
  -- keyboard port
166 
  signal keyboard_data_out : std_logic_vector(7 downto 0);
167 
  signal keyboard_cs       : std_logic;
168 
  signal keyboard_irq      : std_logic;
169 
 
170 
  -- Video Display Unit
171 109 davidgb 
  signal vga_clk      : std_logic;
172 20 dilbert57 
  signal vdu_cs       : std_logic;
173 
  signal vdu_data_out : std_logic_vector(7 downto 0);
174 
 
175 19 dilbert57 
  -- RAM
176 
  signal ram_cs       : std_logic; -- memory chip select
177 
  signal ram_data_out : std_logic_vector(7 downto 0);
178 
 
179 
  -- CPU Interface signals
180 
  signal cpu_reset    : Std_Logic;
181 
  signal cpu_clk      : Std_Logic;
182 
  signal cpu_rw       : std_logic;
183 
  signal cpu_vma      : std_logic;
184 
  signal cpu_halt     : std_logic;
185 
  signal cpu_hold     : std_logic;
186 
  signal cpu_firq     : std_logic;
187 
  signal cpu_irq      : std_logic;
188 
  signal cpu_nmi      : std_logic;
189 
  signal cpu_addr     : std_logic_vector(15 downto 0);
190 
  signal cpu_data_in  : std_logic_vector(7 downto 0);
191 
  signal cpu_data_out : std_logic_vector(7 downto 0);
192 
 
193 20 dilbert57 
  -- CLK_50MHZ clock divide by 2
194 
  signal clock_div    : std_logic_vector(1 downto 0);
195 
  signal SysClk       : std_logic;
196 
  signal Reset_n      : std_logic;
197 19 dilbert57 
  signal CountL       : std_logic_vector(23 downto 0);
198 
 
199 
-----------------------------------------------------------------
200 
--
201 
-- CPU09 CPU core
202 
--
203 
-----------------------------------------------------------------
204 
 
205 
component cpu09
206 
  port (
207 109 davidgb 
         clk      :      in std_logic;
208 
    rst      :  in std_logic;
209 
    rw       :  out std_logic;
210 
    vma      :  out std_logic;
211 
    address  : out std_logic_vector(15 downto 0);
212 
         data_out : out std_logic_vector(7 downto 0);
213 
    data_in  :  in std_logic_vector(7 downto 0);
214 
         irq      :  in std_logic;
215 
         nmi      :  in std_logic;
216 
         firq     :  in std_logic;
217 
         halt     :  in std_logic;
218 
         hold     :  in std_logic
219 19 dilbert57 
  );
220 
end component;
221 
 
222 
 
223 
----------------------------------------
224 
--
225 
-- Block RAM Monitor ROM
226 
--
227 
----------------------------------------
228 20 dilbert57 
component mon_rom
229 19 dilbert57 
    Port (
230 109 davidgb 
       clk      : in  std_logic;
231 
                 rst      : in  std_logic;
232 
                 cs       : in  std_logic;
233 
                 rw       : in  std_logic;
234 
       addr     : in  std_logic_vector (10 downto 0);
235 
       data_in  : in  std_logic_vector (7 downto 0);
236 
       data_out : out std_logic_vector (7 downto 0)
237 19 dilbert57 
    );
238 
end component;
239 
 
240 
----------------------------------------
241 
--
242 
-- Block RAM Monitor
243 
--
244 
----------------------------------------
245 
component ram_32k
246 
    Port (
247 109 davidgb 
       clk      : in  std_logic;
248 
                 rst      : in  std_logic;
249 
                 cs       : in  std_logic;
250 
                 rw       : in  std_logic;
251 
       addr     : in  std_logic_vector (14 downto 0);
252 
       data_in  : in  std_logic_vector (7 downto 0);
253 
       data_out : out std_logic_vector (7 downto 0)
254 19 dilbert57 
    );
255 
end component;
256 
 
257 
-----------------------------------------------------------------
258 
--
259 
-- 6822 compatible PIA with counters
260 
--
261 
-----------------------------------------------------------------
262 
 
263 
component pia_timer
264 
        port (
265 
         clk       : in    std_logic;
266 
    rst       : in    std_logic;
267 
    cs        : in    std_logic;
268 
    rw        : in    std_logic;
269 
    addr      : in    std_logic_vector(1 downto 0);
270 
    data_in   : in    std_logic_vector(7 downto 0);
271 
         data_out  : out   std_logic_vector(7 downto 0);
272 
         irqa      : out   std_logic;
273 
         irqb      : out   std_logic
274 
         );
275 
end component;
276 
 
277 20 dilbert57 
 
278 19 dilbert57 
-----------------------------------------------------------------
279 
--
280 20 dilbert57 
-- 6850 ACIA/UART
281 19 dilbert57 
--
282 
-----------------------------------------------------------------
283 
 
284 20 dilbert57 
component ACIA_6850
285 19 dilbert57 
  port (
286 
     clk      : in  Std_Logic;  -- System Clock
287 
     rst      : in  Std_Logic;  -- Reset input (active high)
288 
     cs       : in  Std_Logic;  -- miniUART Chip Select
289 
     rw       : in  Std_Logic;  -- Read / Not Write
290 109 davidgb 
     addr     : in  Std_Logic;  -- Register Select
291 
     data_in  : in  Std_Logic_Vector(7 downto 0); -- Data Bus In
292 
     data_out : out Std_Logic_Vector(7 downto 0); -- Data Bus Out
293 19 dilbert57 
     irq      : out Std_Logic;  -- Interrupt
294 
     RxC      : in  Std_Logic;  -- Receive Baud Clock
295 
     TxC      : in  Std_Logic;  -- Transmit Baud Clock
296 
     RxD      : in  Std_Logic;  -- Receive Data
297 
     TxD      : out Std_Logic;  -- Transmit Data
298 
          DCD_n    : in  Std_Logic;  -- Data Carrier Detect
299 
     CTS_n    : in  Std_Logic;  -- Clear To Send
300 
     RTS_n    : out Std_Logic );  -- Request To send
301 
end component;
302 
 
303 20 dilbert57 
-----------------------------------------------------------------
304 
--
305 
-- ACIA Clock divider
306 
--
307 
-----------------------------------------------------------------
308 19 dilbert57 
 
309 20 dilbert57 
component ACIA_Clock
310 
  generic (
311 109 davidgb 
     SYS_CLK_FREQ  : integer :=  SYS_CLK_FREQ;
312 
          ACIA_CLK_FREQ : integer := ACIA_CLK_FREQ
313 20 dilbert57 
  );
314 
  port (
315 
     clk      : in  Std_Logic;  -- System Clock Input
316 
          ACIA_clk : out Std_logic   -- ACIA Clock output
317 
  );
318 
end component;
319 
 
320 
----------------------------------------
321 
--
322 
-- Timer module
323 
--
324 
----------------------------------------
325 
 
326 
component timer
327 
  port (
328 
     clk       : in std_logic;
329 
     rst       : in std_logic;
330 
     cs        : in std_logic;
331 
     rw        : in std_logic;
332 
     addr      : in std_logic;
333 
     data_in   : in std_logic_vector(7 downto 0);
334 
          data_out  : out std_logic_vector(7 downto 0);
335 59 davidgb 
          irq       : out std_logic
336 20 dilbert57 
          );
337 
end component;
338 
 
339 
------------------------------------------------------------
340 
--
341 
-- Bus Trap logic
342 
--
343 
------------------------------------------------------------
344 
 
345 
component trap
346 
        port (
347 
         clk        : in  std_logic;
348 
    rst        : in  std_logic;
349 
    cs         : in  std_logic;
350 
    rw         : in  std_logic;
351 
    vma        : in  std_logic;
352 
    addr       : in  std_logic_vector(15 downto 0);
353 
    data_in    : in  std_logic_vector(7 downto 0);
354 
         data_out   : out std_logic_vector(7 downto 0);
355 
         irq        : out std_logic
356 
  );
357 
end component;
358 
 
359 
----------------------------------------
360 
--
361 
-- PS/2 Keyboard
362 
--
363 
----------------------------------------
364 
 
365 
component keyboard
366 
  generic(
367 109 davidgb 
  KBD_CLK_FREQ : integer := CPU_CLK_FREQ
368 20 dilbert57 
  );
369 
  port(
370 
  clk             : in    std_logic;
371 
  rst             : in    std_logic;
372 
  cs              : in    std_logic;
373 
  rw              : in    std_logic;
374 
  addr            : in    std_logic;
375 
  data_in         : in    std_logic_vector(7 downto 0);
376 
  data_out        : out   std_logic_vector(7 downto 0);
377 
  irq             : out   std_logic;
378 
  kbd_clk         : inout std_logic;
379 
  kbd_data        : inout std_logic
380 
  );
381 
end component;
382 
 
383 
----------------------------------------
384 
--
385 
-- Video Display Unit.
386 
--
387 
----------------------------------------
388 
component vdu8
389 
      generic(
390 109 davidgb 
        VGA_CLK_FREQ           : integer := VGA_CLK_FREQ; -- 25MHz
391 
             VGA_HOR_CHARS          : integer := 80; -- CHARACTERS 25.6us
392 
             VGA_HOR_CHAR_PIXELS    : integer :=  8; -- PIXELS 0.32us
393 
             VGA_HOR_FRONT_PORCH    : integer := 16; -- PIXELS 0.64us (0.94us)
394 
             VGA_HOR_SYNC           : integer := 96; -- PIXELS 3.84us (3.77us)
395 
             VGA_HOR_BACK_PORCH     : integer := 48; -- PIXELS 1.92us (1.89us)
396 
             VGA_VER_CHARS          : integer := 25; -- CHARACTERS 12.8ms
397 
             VGA_VER_CHAR_LINES     : integer := 16; -- LINES 0.512ms
398 
             VGA_VER_FRONT_PORCH    : integer := 10; -- LINES 0.320ms
399 
             VGA_VER_SYNC           : integer :=  2; -- LINES 0.064ms
400 
             VGA_VER_BACK_PORCH     : integer := 34  -- LINES 1.088ms
401 20 dilbert57 
      );
402 
      port(
403 
                -- control register interface
404 
      vdu_clk      : in  std_logic;      -- CPU Clock - 12.5MHz
405 
      vdu_rst      : in  std_logic;
406 
                vdu_cs       : in  std_logic;
407 
                vdu_rw       : in  std_logic;
408 
                vdu_addr     : in  std_logic_vector(2 downto 0);
409 
      vdu_data_in  : in  std_logic_vector(7 downto 0);
410 
      vdu_data_out : out std_logic_vector(7 downto 0);
411 
 
412 
      -- vga port connections
413 
                vga_clk      : in  std_logic;   -- VGA Pixel Clock - 25 MHz
414 
      vga_red_o    : out std_logic;
415 
      vga_green_o  : out std_logic;
416 
      vga_blue_o   : out std_logic;
417 
      vga_hsync_o  : out std_logic;
418 
      vga_vsync_o  : out std_logic
419 
   );
420 
end component;
421 
 
422 
 
423 19 dilbert57 
component BUFG
424 
port (
425 
     i: in std_logic;
426 
          o: out std_logic
427 
  );
428 
end component;
429 
 
430 
begin
431 
  -----------------------------------------------------------------------------
432 
  -- Instantiation of internal components
433 
  -----------------------------------------------------------------------------
434 
 
435 
my_cpu : cpu09  port map (
436 
         clk         => cpu_clk,
437 
    rst       => cpu_reset,
438 
    rw       => cpu_rw,
439 
    vma       => cpu_vma,
440 
    address   => cpu_addr(15 downto 0),
441 109 davidgb 
         data_out  => cpu_data_out,
442 19 dilbert57 
    data_in   => cpu_data_in,
443 
         irq       => cpu_irq,
444 
         nmi       => cpu_nmi,
445 109 davidgb 
         firq      => cpu_firq,
446 
         halt      => cpu_halt,
447 
         hold      => cpu_hold
448 19 dilbert57 
  );
449 
 
450 20 dilbert57 
my_rom : mon_rom port map (
451 109 davidgb 
       clk      => cpu_clk,
452 
                 rst      => cpu_reset,
453 
                 cs       => rom_cs,
454 
                 rw       => '1',
455 
       addr     => cpu_addr(10 downto 0),
456 
       data_in  => cpu_data_out,
457 
       data_out => rom_data_out
458 19 dilbert57 
    );
459 
 
460 
my_ram : ram_32k port map (
461 109 davidgb 
       clk      => cpu_clk,
462 
                 rst      => cpu_reset,
463 
                 cs       => ram_cs,
464 
                 rw       => cpu_rw,
465 
       addr     => cpu_addr(14 downto 0),
466 
       data_in  => cpu_data_out,
467 
       data_out => ram_data_out
468 19 dilbert57 
    );
469 
 
470 
my_pia  : pia_timer port map (
471 
         clk         => cpu_clk,
472 
         rst       => cpu_reset,
473 
    cs        => pia_cs,
474 
         rw        => cpu_rw,
475 
    addr      => cpu_addr(1 downto 0),
476 
         data_in   => cpu_data_out,
477 
         data_out  => pia_data_out,
478 
    irqa      => pia_irq_a,
479 
    irqb      => pia_irq_b
480 
         );
481 
 
482 20 dilbert57 
 
483 
----------------------------------------
484 
--
485 
-- ACIA/UART Serial interface
486 
--
487 
----------------------------------------
488 
my_ACIA  : ACIA_6850 port map (
489 19 dilbert57 
         clk         => cpu_clk,
490 
         rst       => cpu_reset,
491 
    cs        => uart_cs,
492 
         rw        => cpu_rw,
493 109 davidgb 
    addr      => cpu_addr(0),
494 
         data_in   => cpu_data_out,
495 
         data_out  => uart_data_out,
496 19 dilbert57 
    irq       => uart_irq,
497 20 dilbert57 
         RxC       => uart_clk,
498 
         TxC       => uart_clk,
499 
         RxD       => rxbit,
500 
         TxD       => txbit,
501 19 dilbert57 
         DCD_n     => dcd_n,
502 
         CTS_n     => cts_n,
503 
         RTS_n     => rts_n
504 
         );
505 
 
506 20 dilbert57 
----------------------------------------
507 
--
508 
-- ACIA Clock
509 
--
510 
----------------------------------------
511 
my_ACIA_Clock : ACIA_Clock
512 
  generic map(
513 109 davidgb 
    SYS_CLK_FREQ  => SYS_CLK_FREQ,
514 
         ACIA_CLK_FREQ => ACIA_CLK_FREQ
515 20 dilbert57 
  )
516 
  port map(
517 
    clk        => SysClk,
518 
    acia_clk   => uart_clk
519 
  );
520 19 dilbert57 
 
521 20 dilbert57 
 
522 
 
523 
----------------------------------------
524 
--
525 
-- PS/2 Keyboard Interface
526 
--
527 
----------------------------------------
528 
my_keyboard : keyboard
529 
   generic map (
530 109 davidgb 
        KBD_CLK_FREQ => CPU_CLK_FREQ
531 20 dilbert57 
        )
532 
   port map(
533 
        clk          => cpu_clk,
534 
        rst          => cpu_reset,
535 
        cs           => keyboard_cs,
536 
        rw           => cpu_rw,
537 
        addr         => cpu_addr(0),
538 
        data_in      => cpu_data_out(7 downto 0),
539 
        data_out     => keyboard_data_out(7 downto 0),
540 
        irq          => keyboard_irq,
541 
        kbd_clk      => PS2_CLK,
542 
        kbd_data     => PS2_DATA
543 
        );
544 
 
545 
----------------------------------------
546 
--
547 
-- Video Display Unit instantiation
548 
--
549 
----------------------------------------
550 
my_vdu : vdu8
551 
  generic map(
552 109 davidgb 
      VGA_CLK_FREQ           => VGA_CLK_FREQ, -- HZ
553 20 dilbert57 
           VGA_HOR_CHARS          => 80, -- CHARACTERS
554 109 davidgb 
           VGA_HOR_CHAR_PIXELS    =>  8,  -- PIXELS
555 
           VGA_HOR_FRONT_PORCH    => 16, -- PIXELS
556 
           VGA_HOR_SYNC           => 96, -- PIXELS
557 
           VGA_HOR_BACK_PORCH     => 48, -- PIXELS
558 20 dilbert57 
           VGA_VER_CHARS          => 25, -- CHARACTERS
559 109 davidgb 
           VGA_VER_CHAR_LINES     => 16, -- LINES
560 
           VGA_VER_FRONT_PORCH    => 10, -- LINES
561 
           VGA_VER_SYNC           =>  2, -- LINES
562 
           VGA_VER_FRONT_PORCH    => 34  -- LINES
563 20 dilbert57 
  )
564 
  port map(
565 
 
566 
                -- Control Registers
567 
                vdu_clk       => cpu_clk,                                        -- 25 MHz System Clock in
568 
      vdu_rst       => cpu_reset,
569 
                vdu_cs        => vdu_cs,
570 
                vdu_rw        => cpu_rw,
571 
                vdu_addr      => cpu_addr(2 downto 0),
572 
                vdu_data_in   => cpu_data_out,
573 
                vdu_data_out  => vdu_data_out,
574 
 
575 
      -- vga port connections
576 109 davidgb 
      vga_clk       => vga_clk,                                  -- 25 MHz VDU pixel clock
577 20 dilbert57 
      vga_red_o     => vga_red,
578 
      vga_green_o   => vga_green,
579 
      vga_blue_o    => vga_blue,
580 
      vga_hsync_o   => vga_hsync,
581 
      vga_vsync_o   => vga_vsync
582 
   );
583 
 
584 
 
585 
----------------------------------------
586 
--
587 
-- Timer Module
588 
--
589 
----------------------------------------
590 
my_timer  : timer port map (
591 
    clk       => cpu_clk,
592 
         rst       => cpu_reset,
593 
    cs        => timer_cs,
594 
         rw        => cpu_rw,
595 
    addr      => cpu_addr(0),
596 
         data_in   => cpu_data_out,
597 
         data_out  => timer_data_out,
598 59 davidgb 
    irq       => timer_irq
599 20 dilbert57 
    );
600 
 
601 
----------------------------------------
602 
--
603 
-- Bus Trap Interrupt logic
604 
--
605 
----------------------------------------
606 
my_trap : trap port map (
607 
         clk        => cpu_clk,
608 
    rst        => cpu_reset,
609 
    cs         => trap_cs,
610 
    rw         => cpu_rw,
611 
         vma        => cpu_vma,
612 
    addr       => cpu_addr,
613 
    data_in    => cpu_data_out,
614 
         data_out   => trap_data_out,
615 
         irq        => trap_irq
616 
    );
617 
 
618 
--
619 
-- 25 MHz CPU clock
620 
--
621 
cpu_clk_buffer : BUFG port map(
622 
    i => clock_div(0),
623 19 dilbert57 
         o => cpu_clk
624 20 dilbert57 
    );
625 
 
626 
--
627 
-- 25 MHz VGA Pixel clock
628 
--
629 
vga_clk_buffer : BUFG port map(
630 
    i => clock_div(0),
631 109 davidgb 
         o => vga_clk
632 19 dilbert57 
    );
633 
 
634 
----------------------------------------------------------------------
635 
--
636 
-- Process to decode memory map
637 
--
638 
----------------------------------------------------------------------
639 
 
640 20 dilbert57 
mem_decode: process( cpu_clk, Reset_n,
641 19 dilbert57 
                     cpu_addr, cpu_rw, cpu_vma,
642 20 dilbert57 
                                              rom_data_out,
643 19 dilbert57 
                                                        ram_data_out,
644 20 dilbert57 
                                                   timer_data_out,
645 
                                                        trap_data_out,
646 
                                                        pia_data_out,
647 19 dilbert57 
                                                   uart_data_out,
648 20 dilbert57 
                                                        keyboard_data_out,
649 
                                                        vdu_data_out )
650 
variable decode_addr : std_logic_vector(3 downto 0);
651 19 dilbert57 
begin
652 20 dilbert57 
--    decode_addr := dat_addr(3 downto 0) & cpu_addr(11);
653 
    decode_addr := cpu_addr(15 downto 12);
654 
 
655 
      case decode_addr is
656 19 dilbert57 
           --
657 20 dilbert57 
                -- SBUG/KBUG/SYS09BUG Monitor ROM $F800 - $FFFF
658 19 dilbert57 
                --
659 20 dilbert57 
                when "1111" => -- $F000 - $FFFF
660 19 dilbert57 
                   cpu_data_in <= rom_data_out;
661 20 dilbert57 
                        rom_cs      <= cpu_vma;              -- read ROM
662 19 dilbert57 
                        ram_cs      <= '0';
663 
                        uart_cs     <= '0';
664 20 dilbert57 
                        timer_cs    <= '0';
665 
                        trap_cs     <= '0';
666 19 dilbert57 
                        pia_cs      <= '0';
667 20 dilbert57 
                        keyboard_cs <= '0';
668 
                        vdu_cs      <= '0';
669 
 
670 19 dilbert57 
      --
671 20 dilbert57 
                -- IO Devices $E000 - $EFFF
672 19 dilbert57 
                --
673 20 dilbert57 
                when "1110" => -- $E000 - $E7FF
674 19 dilbert57 
                        rom_cs    <= '0';
675 
                        ram_cs    <= '0';
676 20 dilbert57 
                   case cpu_addr(7 downto 4) is
677 19 dilbert57 
                        --
678 20 dilbert57 
                        -- UART / ACIA $E000
679 19 dilbert57 
                        --
680 20 dilbert57 
                        when "0000" => -- $E000
681 
                     cpu_data_in <= uart_data_out;
682 
                          uart_cs     <= cpu_vma;
683 
                          timer_cs    <= '0';
684 
                          trap_cs     <= '0';
685 
                          pia_cs      <= '0';
686 
                          keyboard_cs <= '0';
687 
                          vdu_cs      <= '0';
688 
 
689 
                        --
690 
                        -- WD1771 FDC sites at $E010-$E01F
691 
                        --
692 
                        when "0001" => -- $E010
693 
           cpu_data_in <= (others => '0');
694 19 dilbert57 
                          uart_cs     <= '0';
695 20 dilbert57 
                          timer_cs    <= '0';
696 
                          trap_cs     <= '0';
697 
                          pia_cs      <= '0';
698 
                          keyboard_cs <= '0';
699 
                          vdu_cs      <= '0';
700 
 
701 
         --
702 
         -- Keyboard port $E020 - $E02F
703 19 dilbert57 
                        --
704 20 dilbert57 
                        when "0010" => -- $E020
705 
           cpu_data_in <= keyboard_data_out;
706 
                          uart_cs     <= '0';
707 
           timer_cs    <= '0';
708 
                          trap_cs     <= '0';
709 
                          pia_cs      <= '0';
710 
                          keyboard_cs <= cpu_vma;
711 
                          vdu_cs      <= '0';
712 
 
713 
         --
714 
         -- VDU port $E030 - $E03F
715 19 dilbert57 
                        --
716 20 dilbert57 
                        when "0011" => -- $E030
717 
           cpu_data_in <= vdu_data_out;
718 
                          uart_cs     <= '0';
719 
           timer_cs    <= '0';
720 
                          trap_cs     <= '0';
721 
                          pia_cs      <= '0';
722 
                          keyboard_cs <= '0';
723 
                          vdu_cs      <= cpu_vma;
724 19 dilbert57 
 
725 20 dilbert57 
         --
726 
                        -- Compact Flash $E040 - $E04F
727 
                        --
728 
                        when "0100" => -- $E040
729 
           cpu_data_in <= (others => '0');
730 19 dilbert57 
                          uart_cs     <= '0';
731 20 dilbert57 
                          timer_cs    <= '0';
732 
                          trap_cs     <= '0';
733 
                          pia_cs      <= '0';
734 
                          keyboard_cs <= '0';
735 
                          vdu_cs      <= '0';
736 
 
737 
         --
738 
         -- Timer $E050 - $E05F
739 
                        --
740 
                        when "0101" => -- $E050
741 
           cpu_data_in <= timer_data_out;
742 
                          uart_cs     <= '0';
743 
           timer_cs    <= cpu_vma;
744 
                          trap_cs     <= '0';
745 
                          pia_cs      <= '0';
746 
                          keyboard_cs <= '0';
747 
                          vdu_cs      <= '0';
748 
 
749 
         --
750 
         -- Bus Trap Logic $E060 - $E06F
751 
                        --
752 
                        when "0110" => -- $E060
753 
           cpu_data_in <= trap_data_out;
754 
                          uart_cs     <= '0';
755 
           timer_cs    <= '0';
756 
                          trap_cs     <= cpu_vma;
757 
                          pia_cs      <= '0';
758 
                          keyboard_cs <= '0';
759 
                          vdu_cs      <= '0';
760 
 
761 
         --
762 
         -- I/O port $E070 - $E07F
763 
                        --
764 
                        when "0111" => -- $E070
765 
           cpu_data_in <= pia_data_out;
766 
                          uart_cs     <= '0';
767 
           timer_cs    <= '0';
768 
                          trap_cs     <= '0';
769 
                          pia_cs      <= cpu_vma;
770 
                          keyboard_cs <= '0';
771 
                          vdu_cs      <= '0';
772 
 
773 
                        when others => -- $E080 to $E7FF
774 
           cpu_data_in <= (others => '0');
775 
                          uart_cs     <= '0';
776 
                          timer_cs    <= '0';
777 
                          trap_cs     <= '0';
778 
                          pia_cs      <= '0';
779 
                          keyboard_cs <= '0';
780 
                          vdu_cs      <= '0';
781 19 dilbert57 
                   end case;
782 20 dilbert57 
 
783 19 dilbert57 
                --
784 20 dilbert57 
                -- $8000 to $DFFF = null
785 
                --
786 
      when "1101" | "1100" | "1011" | "1010" |
787 
                     "1001" | "1000" =>
788 
                  cpu_data_in <= (others => '0');
789 
                  rom_cs      <= '0';
790 
                  ram_cs      <= '0';
791 
                  uart_cs     <= '0';
792 
                  timer_cs    <= '0';
793 
                  trap_cs     <= '0';
794 
                  pia_cs      <= '0';
795 
                  keyboard_cs <= '0';
796 
                  vdu_cs      <= '0';
797 
                --
798 19 dilbert57 
                -- Everything else is RAM
799 
                --
800 
                when others =>
801 
                  cpu_data_in <= ram_data_out;
802 
                  rom_cs      <= '0';
803 
                  ram_cs      <= cpu_vma;
804 
                  uart_cs     <= '0';
805 20 dilbert57 
                  timer_cs    <= '0';
806 
                  trap_cs     <= '0';
807 
                  pia_cs      <= '0';
808 
                  keyboard_cs <= '0';
809 
                  vdu_cs      <= '0';
810 
                end case;
811 19 dilbert57 
end process;
812 
 
813 
--
814 
-- Interrupts and other bus control signals
815 
--
816 20 dilbert57 
interrupts : process( Reset_n,
817 
                      pia_irq_a, pia_irq_b, uart_irq, trap_irq, timer_irq, keyboard_irq
818 19 dilbert57 
                                                         )
819 
begin
820 20 dilbert57 
         cpu_reset <= not Reset_n; -- CPU reset is active high
821 
    cpu_irq   <= uart_irq or keyboard_irq;
822 
         cpu_nmi   <= pia_irq_a or trap_irq;
823 
         cpu_firq  <= pia_irq_b or timer_irq;
824 19 dilbert57 
         cpu_halt  <= '0';
825 
    cpu_hold  <= '0';
826 
end process;
827 
 
828 
--
829 
--
830 20 dilbert57 
my_led_flasher: process( SysClk, Reset_n, CountL )
831 19 dilbert57 
begin
832 20 dilbert57 
    if Reset_n = '0' then
833 
                   CountL <= "000000000000000000000000";
834 
    elsif(SysClk'event and SysClk = '0') then
835 
                   CountL <= CountL + 1;
836 19 dilbert57 
    end if;
837 20 dilbert57 
         LED(7 downto 0) <= CountL(23 downto 16);
838 19 dilbert57 
end process;
839 
 
840 
--
841 20 dilbert57 
-- Clock divider
842 19 dilbert57 
--
843 20 dilbert57 
my_clock_divider: process( SysClk )
844 19 dilbert57 
begin
845 20 dilbert57 
        if SysClk'event and SysClk='0' then
846 
                clock_div <= clock_div + "01";
847 
        end if;
848 19 dilbert57 
end process;
849 
 
850 
DCD_n <= '0';
851 
CTS_n <= '0';
852 20 dilbert57 
Reset_n <= not BTN_SOUTH; -- CPU reset is active high
853 
SysClk <= CLK_50MHZ;
854 
rxbit <= RS232_DCE_RXD;
855 
RS232_DCE_TXD <= txbit;
856 19 dilbert57 
 
857 
end my_computer; --===================== End of architecture =======================--
858 
 

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