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[/] [System09/] [rev_86/] [rtl/] [System09_Digilent_3S500E/] [System09_Digilent_3S500E.vhd] - Blame information for rev 161

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Line No. Rev Author Line
1 59 davidgb
-- $Id: System09_Digilent_3S500E.vhd,v 1.4 2008-08-20 06:00:55 davidgb Exp $
2 19 dilbert57
--===========================================================================----
3
--
4
--  S Y N T H E Z I A B L E    System09 - SOC.
5
--
6
--  This core adheres to the GNU public license  
7
--
8
-- File name      : System09.vhd
9
--
10
-- Purpose        : Top level file for 6809 compatible system on a chip
11
--                  Designed with Xilinx XC3S500E Spartan 3E FPGA.
12
--                  Implemented With Digilent Xilinx Starter FPGA board,
13
--
14
-- Dependencies   : ieee.Std_Logic_1164
15
--                  ieee.std_logic_unsigned
16
--                  ieee.std_logic_arith
17
--                  ieee.numeric_std
18
--
19
-- Uses           : mon_rom  (kbug_rom2k.vhd)       Monitor ROM
20
--                  cpu09    (cpu09.vhd)      CPU core
21
--                  miniuart (minitUART3.vhd) ACIA / MiniUART
22
--                           (rxunit3.vhd)
23
--                           (tx_unit3.vhd)
24
-- 
25
-- Author         : John E. Kent      
26
--                  dilbert57@opencores.org      
27
--
28
--===========================================================================----
29
--
30
-- Revision History:
31
--===========================================================================--
32
-- Version 0.1 - 20 March 2003
33
-- Version 0.2 - 30 March 2003
34
-- Version 0.3 - 29 April 2003
35
-- Version 0.4 - 29 June 2003
36
--
37
-- Version 0.5 - 19 July 2003
38
-- prints out "Hello World"
39
--
40
-- Version 0.6 - 5 September 2003
41
-- Runs SBUG
42
--
43
-- Version 1.0- 6 Sep 2003 - John Kent
44
-- Inverted CLK_50MHZ
45
-- Initial release to Open Cores
46
--
47
-- Version 1.1 - 17 Jan 2004 - John Kent
48
-- Updated miniUart.
49
--
50
-- Version 1.2 - 25 Jan 2004 - John Kent
51
-- removed signals "test_alu" and "test_cc" 
52
-- Trap hardware re-instated.
53
--
54
-- Version 1.3 - 11 Feb 2004 - John Kent
55
-- Designed forked off to produce System09_VDU
56
-- Added VDU component
57
--      VDU runs at 25MHz and divides the clock by 2 for the CPU
58
-- UART Runs at 57.6 Kbps
59
--
60
-- Version 2.0 - 2 September 2004 - John Kent
61
-- ported to Digilent Xilinx Spartan3 starter board
62
--      removed Compaact Flash and Trap Logic.
63
-- Replaced SBUG with KBug9s
64
--
65
-- Version 3.0 - 22 April 2006 - John Kent
66
-- Port to Digilent Spartan 3E Starter board
67
-- Removed keyboard, vdu, timer, and trap logic
68
-- added PIA with counters attached.
69
-- Uses 32Kbytes of internal Block RAM
70 20 dilbert57
--
71
-- Version 4.0 - 8th April 2007 - John kent
72
-- Added VDU and PS/2 keyboard
73
-- Updated miniUART to ACIA6850
74
-- Reduce monitor ROM to 2KB
75
-- Re-assigned I/O port assignments so it is possible to run KBUG9
76
-- $E000 - ACIA
77
-- $E020 - Keyboard
78
-- $E030 - VDU
79
-- $E040 - Compact Flash (not implemented)
80
-- $E050 - Timer
81
-- $E060 - Bus trap
82
-- $E070 - Parallel I/O
83
--
84 19 dilbert57
--===========================================================================--
85
library ieee;
86
   use ieee.std_logic_1164.all;
87
   use IEEE.STD_LOGIC_ARITH.ALL;
88
   use IEEE.STD_LOGIC_UNSIGNED.ALL;
89
   use ieee.numeric_std.all;
90
 
91 59 davidgb
entity my_system09 is
92 19 dilbert57
  port(
93
    CLK_50MHZ     : in  Std_Logic;  -- System Clock input
94
    BTN_SOUTH     : in  Std_Logic;
95
 
96 20 dilbert57
         -- PS/2 Keyboard
97
         PS2_CLK      : inout Std_logic;
98
         PS2_DATA     : inout Std_Logic;
99
 
100
         -- CRTC output signals
101
         VGA_VSYNC     : out Std_Logic;
102
    VGA_HSYNC     : out Std_Logic;
103
    VGA_BLUE      : out std_logic;
104
    VGA_GREEN     : out std_logic;
105
    VGA_RED       : out std_logic;
106
 
107 19 dilbert57
         -- Uart Interface
108
         RS232_DCE_RXD : in  std_logic;
109
    RS232_DCE_TXD : out std_logic;
110
 
111
         -- LEDS & Switches
112
         LED           : out std_logic_vector(7 downto 0)
113
         );
114 59 davidgb
end my_system09;
115 19 dilbert57
 
116
-------------------------------------------------------------------------------
117
-- Architecture for System09
118
-------------------------------------------------------------------------------
119 59 davidgb
architecture my_computer of my_system09 is
120 19 dilbert57
  -----------------------------------------------------------------------------
121 20 dilbert57
  -- constants
122
  -----------------------------------------------------------------------------
123
  constant SYS_Clock_Frequency  : integer := 50000000;  -- FPGA System Clock
124
  constant PIX_Clock_Frequency  : integer := 25000000;  -- VGA Pixel Clock
125
  constant CPU_Clock_Frequency  : integer := 25000000;  -- CPU Clock
126
  constant BAUD_Rate            : integer := 57600;       -- Baud Rate
127
  constant ACIA_Clock_Frequency : integer := BAUD_Rate * 16;
128
 
129
  -----------------------------------------------------------------------------
130 19 dilbert57
  -- Signals
131
  -----------------------------------------------------------------------------
132
  -- BOOT ROM
133 20 dilbert57
  signal rom_cs         : Std_logic;
134
  signal rom_data_out   : Std_Logic_Vector(7 downto 0);
135 19 dilbert57
 
136
  -- UART Interface signals
137 20 dilbert57
  signal uart_data_out  : Std_Logic_Vector(7 downto 0);
138
  signal uart_cs        : Std_Logic;
139
  signal uart_irq       : Std_Logic;
140
  signal uart_clk       : Std_Logic;
141
  signal rxbit          : Std_Logic;
142
  signal txbit          : Std_Logic;
143
  signal DCD_n          : Std_Logic;
144
  signal RTS_n          : Std_Logic;
145
  signal CTS_n          : Std_Logic;
146 19 dilbert57
 
147 20 dilbert57
  -- timer
148
  signal timer_data_out : std_logic_vector(7 downto 0);
149
  signal timer_cs       : std_logic;
150
  signal timer_irq      : std_logic;
151
 
152
  -- trap
153
  signal trap_cs        : std_logic;
154
  signal trap_data_out  : std_logic_vector(7 downto 0);
155
  signal trap_irq       : std_logic;
156
 
157 19 dilbert57
  -- PIA Interface signals
158 20 dilbert57
  signal pia_data_out   : Std_Logic_Vector(7 downto 0);
159
  signal pia_cs         : Std_Logic;
160
  signal pia_irq_a      : Std_Logic;
161
  signal pia_irq_b      : Std_Logic;
162 19 dilbert57
 
163 20 dilbert57
  -- keyboard port
164
  signal keyboard_data_out : std_logic_vector(7 downto 0);
165
  signal keyboard_cs       : std_logic;
166
  signal keyboard_irq      : std_logic;
167
 
168
  -- Video Display Unit
169
  signal pix_clk      : std_logic;
170
  signal vdu_cs       : std_logic;
171
  signal vdu_data_out : std_logic_vector(7 downto 0);
172
 
173 19 dilbert57
  -- RAM
174
  signal ram_cs       : std_logic; -- memory chip select
175
  signal ram_data_out : std_logic_vector(7 downto 0);
176
 
177
  -- CPU Interface signals
178
  signal cpu_reset    : Std_Logic;
179
  signal cpu_clk      : Std_Logic;
180
  signal cpu_rw       : std_logic;
181
  signal cpu_vma      : std_logic;
182
  signal cpu_halt     : std_logic;
183
  signal cpu_hold     : std_logic;
184
  signal cpu_firq     : std_logic;
185
  signal cpu_irq      : std_logic;
186
  signal cpu_nmi      : std_logic;
187
  signal cpu_addr     : std_logic_vector(15 downto 0);
188
  signal cpu_data_in  : std_logic_vector(7 downto 0);
189
  signal cpu_data_out : std_logic_vector(7 downto 0);
190
 
191 20 dilbert57
  -- CLK_50MHZ clock divide by 2
192
  signal clock_div    : std_logic_vector(1 downto 0);
193
  signal SysClk       : std_logic;
194
  signal Reset_n      : std_logic;
195 19 dilbert57
  signal CountL       : std_logic_vector(23 downto 0);
196
 
197
-----------------------------------------------------------------
198
--
199
-- CPU09 CPU core
200
--
201
-----------------------------------------------------------------
202
 
203
component cpu09
204
  port (
205
         clk:        in std_logic;
206
    rst:      in        std_logic;
207
    rw:      out        std_logic;              -- Asynchronous memory interface
208
    vma:             out        std_logic;
209
    address:  out       std_logic_vector(15 downto 0);
210
    data_in:  in        std_logic_vector(7 downto 0);
211
         data_out: out std_logic_vector(7 downto 0);
212
         halt:     in  std_logic;
213
         hold:     in  std_logic;
214
         irq:      in  std_logic;
215
         nmi:      in  std_logic;
216
         firq:     in  std_logic
217
  );
218
end component;
219
 
220
 
221
----------------------------------------
222
--
223
-- Block RAM Monitor ROM
224
--
225
----------------------------------------
226 20 dilbert57
component mon_rom
227 19 dilbert57
    Port (
228
       clk   : in  std_logic;
229
                 rst   : in  std_logic;
230
                 cs    : in  std_logic;
231
                 rw    : in  std_logic;
232 20 dilbert57
       addr  : in  std_logic_vector (10 downto 0);
233 19 dilbert57
       rdata : out std_logic_vector (7 downto 0);
234
       wdata : in  std_logic_vector (7 downto 0)
235
    );
236
end component;
237
 
238
----------------------------------------
239
--
240
-- Block RAM Monitor
241
--
242
----------------------------------------
243
component ram_32k
244
    Port (
245
       clk   : in  std_logic;
246
                 rst   : in  std_logic;
247
                 cs    : in  std_logic;
248
                 rw    : in  std_logic;
249
       addr  : in  std_logic_vector (14 downto 0);
250
       rdata : out std_logic_vector (7 downto 0);
251
       wdata : in  std_logic_vector (7 downto 0)
252
    );
253
end component;
254
 
255
-----------------------------------------------------------------
256
--
257
-- 6822 compatible PIA with counters
258
--
259
-----------------------------------------------------------------
260
 
261
component pia_timer
262
        port (
263
         clk       : in    std_logic;
264
    rst       : in    std_logic;
265
    cs        : in    std_logic;
266
    rw        : in    std_logic;
267
    addr      : in    std_logic_vector(1 downto 0);
268
    data_in   : in    std_logic_vector(7 downto 0);
269
         data_out  : out   std_logic_vector(7 downto 0);
270
         irqa      : out   std_logic;
271
         irqb      : out   std_logic
272
         );
273
end component;
274
 
275 20 dilbert57
 
276 19 dilbert57
-----------------------------------------------------------------
277
--
278 20 dilbert57
-- 6850 ACIA/UART
279 19 dilbert57
--
280
-----------------------------------------------------------------
281
 
282 20 dilbert57
component ACIA_6850
283 19 dilbert57
  port (
284
     clk      : in  Std_Logic;  -- System Clock
285
     rst      : in  Std_Logic;  -- Reset input (active high)
286
     cs       : in  Std_Logic;  -- miniUART Chip Select
287
     rw       : in  Std_Logic;  -- Read / Not Write
288
     irq      : out Std_Logic;  -- Interrupt
289
     Addr     : in  Std_Logic;  -- Register Select
290
     DataIn   : in  Std_Logic_Vector(7 downto 0); -- Data Bus In 
291
     DataOut  : out Std_Logic_Vector(7 downto 0); -- Data Bus Out
292
     RxC      : in  Std_Logic;  -- Receive Baud Clock
293
     TxC      : in  Std_Logic;  -- Transmit Baud Clock
294
     RxD      : in  Std_Logic;  -- Receive Data
295
     TxD      : out Std_Logic;  -- Transmit Data
296
          DCD_n    : in  Std_Logic;  -- Data Carrier Detect
297
     CTS_n    : in  Std_Logic;  -- Clear To Send
298
     RTS_n    : out Std_Logic );  -- Request To send
299
end component;
300
 
301 20 dilbert57
-----------------------------------------------------------------
302
--
303
-- ACIA Clock divider
304
--
305
-----------------------------------------------------------------
306 19 dilbert57
 
307 20 dilbert57
component ACIA_Clock
308
  generic (
309
     SYS_Clock_Frequency  : integer :=  SYS_Clock_Frequency;
310
          ACIA_Clock_Frequency : integer := ACIA_Clock_Frequency
311
  );
312
  port (
313
     clk      : in  Std_Logic;  -- System Clock Input
314
          ACIA_clk : out Std_logic   -- ACIA Clock output
315
  );
316
end component;
317
 
318
----------------------------------------
319
--
320
-- Timer module
321
--
322
----------------------------------------
323
 
324
component timer
325
  port (
326
     clk       : in std_logic;
327
     rst       : in std_logic;
328
     cs        : in std_logic;
329
     rw        : in std_logic;
330
     addr      : in std_logic;
331
     data_in   : in std_logic_vector(7 downto 0);
332
          data_out  : out std_logic_vector(7 downto 0);
333 59 davidgb
          irq       : out std_logic
334
          -- ;
335
     -- timer_in  : in std_logic;
336
          -- timer_out : out std_logic
337 20 dilbert57
          );
338
end component;
339
 
340
------------------------------------------------------------
341
--
342
-- Bus Trap logic
343
--
344
------------------------------------------------------------
345
 
346
component trap
347
        port (
348
         clk        : in  std_logic;
349
    rst        : in  std_logic;
350
    cs         : in  std_logic;
351
    rw         : in  std_logic;
352
    vma        : in  std_logic;
353
    addr       : in  std_logic_vector(15 downto 0);
354
    data_in    : in  std_logic_vector(7 downto 0);
355
         data_out   : out std_logic_vector(7 downto 0);
356
         irq        : out std_logic
357
  );
358
end component;
359
 
360
----------------------------------------
361
--
362
-- PS/2 Keyboard
363
--
364
----------------------------------------
365
 
366
component keyboard
367
  generic(
368
  KBD_Clock_Frequency : integer := CPU_Clock_Frequency
369
  );
370
  port(
371
  clk             : in    std_logic;
372
  rst             : in    std_logic;
373
  cs              : in    std_logic;
374
  rw              : in    std_logic;
375
  addr            : in    std_logic;
376
  data_in         : in    std_logic_vector(7 downto 0);
377
  data_out        : out   std_logic_vector(7 downto 0);
378
  irq             : out   std_logic;
379
  kbd_clk         : inout std_logic;
380
  kbd_data        : inout std_logic
381
  );
382
end component;
383
 
384
----------------------------------------
385
--
386
-- Video Display Unit.
387
--
388
----------------------------------------
389
component vdu8
390
      generic(
391
        VDU_CLOCK_FREQUENCY    : integer := CPU_Clock_Frequency; -- HZ
392
        VGA_CLOCK_FREQUENCY    : integer := PIX_Clock_Frequency; -- HZ
393
             VGA_HOR_CHARS          : integer := 80; -- CHARACTERS
394
             VGA_VER_CHARS          : integer := 25; -- CHARACTERS
395
             VGA_PIXELS_PER_CHAR    : integer := 8;  -- PIXELS
396
             VGA_LINES_PER_CHAR     : integer := 16; -- LINES
397
             VGA_HOR_BACK_PORCH     : integer := 40; -- PIXELS
398
             VGA_HOR_SYNC           : integer := 96; -- PIXELS
399
             VGA_HOR_FRONT_PORCH    : integer := 24; -- PIXELS
400
             VGA_VER_BACK_PORCH     : integer := 13; -- LINES
401
             VGA_VER_SYNC           : integer := 1;  -- LINES
402
             VGA_VER_FRONT_PORCH    : integer := 36  -- LINES
403
      );
404
      port(
405
                -- control register interface
406
      vdu_clk      : in  std_logic;      -- CPU Clock - 12.5MHz
407
      vdu_rst      : in  std_logic;
408
                vdu_cs       : in  std_logic;
409
                vdu_rw       : in  std_logic;
410
                vdu_addr     : in  std_logic_vector(2 downto 0);
411
      vdu_data_in  : in  std_logic_vector(7 downto 0);
412
      vdu_data_out : out std_logic_vector(7 downto 0);
413
 
414
      -- vga port connections
415
                vga_clk      : in  std_logic;   -- VGA Pixel Clock - 25 MHz
416
      vga_red_o    : out std_logic;
417
      vga_green_o  : out std_logic;
418
      vga_blue_o   : out std_logic;
419
      vga_hsync_o  : out std_logic;
420
      vga_vsync_o  : out std_logic
421
   );
422
end component;
423
 
424
 
425 19 dilbert57
component BUFG
426
port (
427
     i: in std_logic;
428
          o: out std_logic
429
  );
430
end component;
431
 
432
begin
433
  -----------------------------------------------------------------------------
434
  -- Instantiation of internal components
435
  -----------------------------------------------------------------------------
436
 
437
my_cpu : cpu09  port map (
438
         clk         => cpu_clk,
439
    rst       => cpu_reset,
440
    rw       => cpu_rw,
441
    vma       => cpu_vma,
442
    address   => cpu_addr(15 downto 0),
443
    data_in   => cpu_data_in,
444
         data_out  => cpu_data_out,
445
         halt      => cpu_halt,
446
         hold      => cpu_hold,
447
         irq       => cpu_irq,
448
         nmi       => cpu_nmi,
449
         firq      => cpu_firq
450
  );
451
 
452 20 dilbert57
my_rom : mon_rom port map (
453 19 dilbert57
       clk   => cpu_clk,
454
                 rst   => cpu_reset,
455
                 cs    => rom_cs,
456
                 rw    => '1',
457 20 dilbert57
       addr  => cpu_addr(10 downto 0),
458 19 dilbert57
       rdata => rom_data_out,
459
       wdata => cpu_data_out
460
    );
461
 
462
my_ram : ram_32k port map (
463
       clk   => cpu_clk,
464
                 rst   => cpu_reset,
465
                 cs    => ram_cs,
466
                 rw    => cpu_rw,
467
       addr  => cpu_addr(14 downto 0),
468
       rdata => ram_data_out,
469
       wdata => cpu_data_out
470
    );
471
 
472
my_pia  : pia_timer port map (
473
         clk         => cpu_clk,
474
         rst       => cpu_reset,
475
    cs        => pia_cs,
476
         rw        => cpu_rw,
477
    addr      => cpu_addr(1 downto 0),
478
         data_in   => cpu_data_out,
479
         data_out  => pia_data_out,
480
    irqa      => pia_irq_a,
481
    irqb      => pia_irq_b
482
         );
483
 
484 20 dilbert57
 
485
----------------------------------------
486
--
487
-- ACIA/UART Serial interface
488
--
489
----------------------------------------
490
my_ACIA  : ACIA_6850 port map (
491 19 dilbert57
         clk         => cpu_clk,
492
         rst       => cpu_reset,
493
    cs        => uart_cs,
494
         rw        => cpu_rw,
495
    irq       => uart_irq,
496
    Addr      => cpu_addr(0),
497
         Datain    => cpu_data_out,
498
         DataOut   => uart_data_out,
499 20 dilbert57
         RxC       => uart_clk,
500
         TxC       => uart_clk,
501
         RxD       => rxbit,
502
         TxD       => txbit,
503 19 dilbert57
         DCD_n     => dcd_n,
504
         CTS_n     => cts_n,
505
         RTS_n     => rts_n
506
         );
507
 
508 20 dilbert57
----------------------------------------
509
--
510
-- ACIA Clock
511
--
512
----------------------------------------
513
my_ACIA_Clock : ACIA_Clock
514
  generic map(
515
    SYS_Clock_Frequency  => SYS_Clock_Frequency,
516
         ACIA_Clock_Frequency => ACIA_Clock_Frequency
517
  )
518
  port map(
519
    clk        => SysClk,
520
    acia_clk   => uart_clk
521
  );
522 19 dilbert57
 
523 20 dilbert57
 
524
 
525
----------------------------------------
526
--
527
-- PS/2 Keyboard Interface
528
--
529
----------------------------------------
530
my_keyboard : keyboard
531
   generic map (
532
        KBD_Clock_Frequency => CPU_Clock_frequency
533
        )
534
   port map(
535
        clk          => cpu_clk,
536
        rst          => cpu_reset,
537
        cs           => keyboard_cs,
538
        rw           => cpu_rw,
539
        addr         => cpu_addr(0),
540
        data_in      => cpu_data_out(7 downto 0),
541
        data_out     => keyboard_data_out(7 downto 0),
542
        irq          => keyboard_irq,
543
        kbd_clk      => PS2_CLK,
544
        kbd_data     => PS2_DATA
545
        );
546
 
547
----------------------------------------
548
--
549
-- Video Display Unit instantiation
550
--
551
----------------------------------------
552
my_vdu : vdu8
553
  generic map(
554
      VDU_CLOCK_FREQUENCY    => CPU_Clock_Frequency, -- HZ
555
      VGA_CLOCK_FREQUENCY    => PIX_Clock_Frequency, -- HZ
556
           VGA_HOR_CHARS          => 80, -- CHARACTERS
557
           VGA_VER_CHARS          => 25, -- CHARACTERS
558
           VGA_PIXELS_PER_CHAR    => 8,  -- PIXELS
559
           VGA_LINES_PER_CHAR     => 16, -- LINES
560
           VGA_HOR_BACK_PORCH     => 40, -- PIXELS
561
           VGA_HOR_SYNC           => 96, -- PIXELS
562
           VGA_HOR_FRONT_PORCH    => 24, -- PIXELS
563
           VGA_VER_BACK_PORCH     => 13, -- LINES
564
           VGA_VER_SYNC           => 1,  -- LINES
565
           VGA_VER_FRONT_PORCH    => 36  -- LINES
566
  )
567
  port map(
568
 
569
                -- Control Registers
570
                vdu_clk       => cpu_clk,                                        -- 25 MHz System Clock in
571
      vdu_rst       => cpu_reset,
572
                vdu_cs        => vdu_cs,
573
                vdu_rw        => cpu_rw,
574
                vdu_addr      => cpu_addr(2 downto 0),
575
                vdu_data_in   => cpu_data_out,
576
                vdu_data_out  => vdu_data_out,
577
 
578
      -- vga port connections
579
      vga_clk       => pix_clk,                                  -- 25 MHz VDU pixel clock
580
      vga_red_o     => vga_red,
581
      vga_green_o   => vga_green,
582
      vga_blue_o    => vga_blue,
583
      vga_hsync_o   => vga_hsync,
584
      vga_vsync_o   => vga_vsync
585
   );
586
 
587
 
588
----------------------------------------
589
--
590
-- Timer Module
591
--
592
----------------------------------------
593
my_timer  : timer port map (
594
    clk       => cpu_clk,
595
         rst       => cpu_reset,
596
    cs        => timer_cs,
597
         rw        => cpu_rw,
598
    addr      => cpu_addr(0),
599
         data_in   => cpu_data_out,
600
         data_out  => timer_data_out,
601 59 davidgb
    irq       => timer_irq
602
         -- ,
603
         -- timer_in  => CountL(5)
604 20 dilbert57
--       timer_out => timer_out
605
    );
606
 
607
----------------------------------------
608
--
609
-- Bus Trap Interrupt logic
610
--
611
----------------------------------------
612
my_trap : trap port map (
613
         clk        => cpu_clk,
614
    rst        => cpu_reset,
615
    cs         => trap_cs,
616
    rw         => cpu_rw,
617
         vma        => cpu_vma,
618
    addr       => cpu_addr,
619
    data_in    => cpu_data_out,
620
         data_out   => trap_data_out,
621
         irq        => trap_irq
622
    );
623
 
624
--
625
-- 25 MHz CPU clock
626
--
627
cpu_clk_buffer : BUFG port map(
628
    i => clock_div(0),
629 19 dilbert57
         o => cpu_clk
630 20 dilbert57
    );
631
 
632
--
633
-- 25 MHz VGA Pixel clock
634
--
635
vga_clk_buffer : BUFG port map(
636
    i => clock_div(0),
637
         o => pix_clk
638 19 dilbert57
    );
639
 
640
----------------------------------------------------------------------
641
--
642
-- Process to decode memory map
643
--
644
----------------------------------------------------------------------
645
 
646 20 dilbert57
mem_decode: process( cpu_clk, Reset_n,
647 19 dilbert57
                     cpu_addr, cpu_rw, cpu_vma,
648 20 dilbert57
                                              rom_data_out,
649 19 dilbert57
                                                        ram_data_out,
650 20 dilbert57
                                                   timer_data_out,
651
                                                        trap_data_out,
652
                                                        pia_data_out,
653 19 dilbert57
                                                   uart_data_out,
654 20 dilbert57
                                                        keyboard_data_out,
655
                                                        vdu_data_out )
656
variable decode_addr : std_logic_vector(3 downto 0);
657 19 dilbert57
begin
658 20 dilbert57
--    decode_addr := dat_addr(3 downto 0) & cpu_addr(11);
659
    decode_addr := cpu_addr(15 downto 12);
660
 
661
      case decode_addr is
662 19 dilbert57
           --
663 20 dilbert57
                -- SBUG/KBUG/SYS09BUG Monitor ROM $F800 - $FFFF
664 19 dilbert57
                --
665 20 dilbert57
                when "1111" => -- $F000 - $FFFF
666 19 dilbert57
                   cpu_data_in <= rom_data_out;
667 20 dilbert57
                        rom_cs      <= cpu_vma;              -- read ROM
668 19 dilbert57
                        ram_cs      <= '0';
669
                        uart_cs     <= '0';
670 20 dilbert57
                        timer_cs    <= '0';
671
                        trap_cs     <= '0';
672 19 dilbert57
                        pia_cs      <= '0';
673 20 dilbert57
                        keyboard_cs <= '0';
674
                        vdu_cs      <= '0';
675
 
676 19 dilbert57
      --
677 20 dilbert57
                -- IO Devices $E000 - $EFFF
678 19 dilbert57
                --
679 20 dilbert57
                when "1110" => -- $E000 - $E7FF
680 19 dilbert57
                        rom_cs    <= '0';
681
                        ram_cs    <= '0';
682 20 dilbert57
                   case cpu_addr(7 downto 4) is
683 19 dilbert57
                        --
684 20 dilbert57
                        -- UART / ACIA $E000
685 19 dilbert57
                        --
686 20 dilbert57
                        when "0000" => -- $E000
687
                     cpu_data_in <= uart_data_out;
688
                          uart_cs     <= cpu_vma;
689
                          timer_cs    <= '0';
690
                          trap_cs     <= '0';
691
                          pia_cs      <= '0';
692
                          keyboard_cs <= '0';
693
                          vdu_cs      <= '0';
694
 
695
                        --
696
                        -- WD1771 FDC sites at $E010-$E01F
697
                        --
698
                        when "0001" => -- $E010
699
           cpu_data_in <= (others => '0');
700 19 dilbert57
                          uart_cs     <= '0';
701 20 dilbert57
                          timer_cs    <= '0';
702
                          trap_cs     <= '0';
703
                          pia_cs      <= '0';
704
                          keyboard_cs <= '0';
705
                          vdu_cs      <= '0';
706
 
707
         --
708
         -- Keyboard port $E020 - $E02F
709 19 dilbert57
                        --
710 20 dilbert57
                        when "0010" => -- $E020
711
           cpu_data_in <= keyboard_data_out;
712
                          uart_cs     <= '0';
713
           timer_cs    <= '0';
714
                          trap_cs     <= '0';
715
                          pia_cs      <= '0';
716
                          keyboard_cs <= cpu_vma;
717
                          vdu_cs      <= '0';
718
 
719
         --
720
         -- VDU port $E030 - $E03F
721 19 dilbert57
                        --
722 20 dilbert57
                        when "0011" => -- $E030
723
           cpu_data_in <= vdu_data_out;
724
                          uart_cs     <= '0';
725
           timer_cs    <= '0';
726
                          trap_cs     <= '0';
727
                          pia_cs      <= '0';
728
                          keyboard_cs <= '0';
729
                          vdu_cs      <= cpu_vma;
730 19 dilbert57
 
731 20 dilbert57
         --
732
                        -- Compact Flash $E040 - $E04F
733
                        --
734
                        when "0100" => -- $E040
735
           cpu_data_in <= (others => '0');
736 19 dilbert57
                          uart_cs     <= '0';
737 20 dilbert57
                          timer_cs    <= '0';
738
                          trap_cs     <= '0';
739
                          pia_cs      <= '0';
740
                          keyboard_cs <= '0';
741
                          vdu_cs      <= '0';
742
 
743
         --
744
         -- Timer $E050 - $E05F
745
                        --
746
                        when "0101" => -- $E050
747
           cpu_data_in <= timer_data_out;
748
                          uart_cs     <= '0';
749
           timer_cs    <= cpu_vma;
750
                          trap_cs     <= '0';
751
                          pia_cs      <= '0';
752
                          keyboard_cs <= '0';
753
                          vdu_cs      <= '0';
754
 
755
         --
756
         -- Bus Trap Logic $E060 - $E06F
757
                        --
758
                        when "0110" => -- $E060
759
           cpu_data_in <= trap_data_out;
760
                          uart_cs     <= '0';
761
           timer_cs    <= '0';
762
                          trap_cs     <= cpu_vma;
763
                          pia_cs      <= '0';
764
                          keyboard_cs <= '0';
765
                          vdu_cs      <= '0';
766
 
767
         --
768
         -- I/O port $E070 - $E07F
769
                        --
770
                        when "0111" => -- $E070
771
           cpu_data_in <= pia_data_out;
772
                          uart_cs     <= '0';
773
           timer_cs    <= '0';
774
                          trap_cs     <= '0';
775
                          pia_cs      <= cpu_vma;
776
                          keyboard_cs <= '0';
777
                          vdu_cs      <= '0';
778
 
779
                        when others => -- $E080 to $E7FF
780
           cpu_data_in <= (others => '0');
781
                          uart_cs     <= '0';
782
                          timer_cs    <= '0';
783
                          trap_cs     <= '0';
784
                          pia_cs      <= '0';
785
                          keyboard_cs <= '0';
786
                          vdu_cs      <= '0';
787 19 dilbert57
                   end case;
788 20 dilbert57
 
789 19 dilbert57
                --
790 20 dilbert57
                -- $8000 to $DFFF = null
791
                --
792
      when "1101" | "1100" | "1011" | "1010" |
793
                     "1001" | "1000" =>
794
                  cpu_data_in <= (others => '0');
795
                  rom_cs      <= '0';
796
                  ram_cs      <= '0';
797
                  uart_cs     <= '0';
798
                  timer_cs    <= '0';
799
                  trap_cs     <= '0';
800
                  pia_cs      <= '0';
801
                  keyboard_cs <= '0';
802
                  vdu_cs      <= '0';
803
                --
804 19 dilbert57
                -- Everything else is RAM
805
                --
806
                when others =>
807
                  cpu_data_in <= ram_data_out;
808
                  rom_cs      <= '0';
809
                  ram_cs      <= cpu_vma;
810
                  uart_cs     <= '0';
811 20 dilbert57
                  timer_cs    <= '0';
812
                  trap_cs     <= '0';
813
                  pia_cs      <= '0';
814
                  keyboard_cs <= '0';
815
                  vdu_cs      <= '0';
816
                end case;
817 19 dilbert57
end process;
818
 
819
--
820
-- Interrupts and other bus control signals
821
--
822 20 dilbert57
interrupts : process( Reset_n,
823
                      pia_irq_a, pia_irq_b, uart_irq, trap_irq, timer_irq, keyboard_irq
824 19 dilbert57
                                                         )
825
begin
826 20 dilbert57
         cpu_reset <= not Reset_n; -- CPU reset is active high
827
    cpu_irq   <= uart_irq or keyboard_irq;
828
         cpu_nmi   <= pia_irq_a or trap_irq;
829
         cpu_firq  <= pia_irq_b or timer_irq;
830 19 dilbert57
         cpu_halt  <= '0';
831
    cpu_hold  <= '0';
832
end process;
833
 
834
--
835
--
836 20 dilbert57
my_led_flasher: process( SysClk, Reset_n, CountL )
837 19 dilbert57
begin
838 20 dilbert57
    if Reset_n = '0' then
839
                   CountL <= "000000000000000000000000";
840
    elsif(SysClk'event and SysClk = '0') then
841
                   CountL <= CountL + 1;
842 19 dilbert57
    end if;
843 20 dilbert57
         LED(7 downto 0) <= CountL(23 downto 16);
844 19 dilbert57
end process;
845
 
846
--
847 20 dilbert57
-- Clock divider
848 19 dilbert57
--
849 20 dilbert57
my_clock_divider: process( SysClk )
850 19 dilbert57
begin
851 20 dilbert57
        if SysClk'event and SysClk='0' then
852
                clock_div <= clock_div + "01";
853
        end if;
854 19 dilbert57
end process;
855
 
856
DCD_n <= '0';
857
CTS_n <= '0';
858 20 dilbert57
Reset_n <= not BTN_SOUTH; -- CPU reset is active high
859
SysClk <= CLK_50MHZ;
860
rxbit <= RS232_DCE_RXD;
861
RS232_DCE_TXD <= txbit;
862 19 dilbert57
 
863
end my_computer; --===================== End of architecture =======================--
864
 

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