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[/] [System09/] [trunk/] [rtl/] [System09_base/] [system09.vhd] - Blame information for rev 169

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1 128 davidgb 
--===========================================================================----
2 
--
3 
--  S Y N T H E Z I A B L E    System09 - SOC.
4 
--
5 
--  www.OpenCores.Org - February 2007
6 
--  This core adheres to the GNU public license
7 
--
8 
-- File name      : System09_Xess_XSA-3S1000.vhd
9 
--
10 
-- Purpose        : Top level file for 6809 compatible system on a chip
11 
--                  Designed with Xilinx XC3S1000 Spartan 3 FPGA.
12 
--                  Implemented With XESS XSA-3S1000 FPGA board.
13 
--                  *** Note ***
14 
--                  This configuration can run Flex9 however it only has
15 
--                  32k bytes of user memory and the VDU is monochrome
16 
--                  The design needs to be updated to use the SDRAM on
17 
--                  the XSA-3S1000 board.
18 
--                  This configuration also lacks a DAT so cannot use
19 
--                  the RAM Disk features of SYS09BUG.
20 
--
21 
-- Dependencies   : ieee.Std_Logic_1164
22 
--                  ieee.std_logic_unsigned
23 
--                  ieee.std_logic_arith
24 
--                  ieee.numeric_std
25 
--                  unisim.vcomponents
26 
--
27 
-- Uses           : mon_rom    (sys09bug_rom4k_b16.vhd) Sys09Bug Monitor ROM
28 
--                  cpu09      (cpu09.vhd)          CPU core
29 
--                  ACIA_6850  (acia6850.vhd)      ACIA / UART
30 
--                  ACIA_Clock (ACIA_Clock.vhd)      ACIA clock.
31 
--                  keyboard   (keyboard.vhd)        PS/2 Keyboard interface
32 
--                             (ps2_keyboard.vhd)
33 
--                             (keymap_rom_slice.vhd) Key map table
34 
--                  vdu8_mono  (vdu8_mono.vhd)        Monochrome VDU
35 
--                             (char_rom2k_b16.vhd)
36 
--                             (ram2k_b16.vhd)
37 
--                  timer      (timer.vhd)            Interrupt timer
38 
--                  trap       (trap.vhd)             Bus condition trap logic
39 
--                  flex_ram   (flex9_ram8k_b16.vhd)  Flex operating system
40 
--                  ram_32K    (ram32k_b16.vhd)       32 KBytes of Block RAM
41 
--
42 
--
43 
-- Author         : John E. Kent
44 
--                  dilbert57@opencores.org
45 
--
46 
-- Memory Map     :
47 
--
48 
-- $0000 - User program RAM (32K Bytes)
49 
-- $C000 - Flex Operating System memory (8K Bytes)
50 
-- $E000 - ACIA (SWTPc)
51 
-- $E010 - Reserved for FD1771 FDC (SWTPc)
52 
-- $E020 - Keyboard
53 
-- $E030 - VDU
54 
-- $E040 - IDE / Compact Flash interface
55 
-- $E050 - Timer
56 
-- $E060 - Bus trap
57 
-- $E070 - Reserced for Parallel I/O (B5-X300)
58 
-- $E080 - Reserved for 6821 PIA (?) (SWTPc)
59 
-- $E090 - Reserved for 6840 PTM (?) (SWTPc)
60 
-- $F000 - Sys09Bug monitor Program (4K Bytes)
61 
--
62 
--===========================================================================----
63 
--
64 
-- Revision History:
65 
--===========================================================================--
66 
-- Version 0.1 - 20 March 2003
67 
-- Version 0.2 - 30 March 2003
68 
-- Version 0.3 - 29 April 2003
69 
-- Version 0.4 - 29 June 2003
70 
--
71 
-- Version 0.5 - 19 July 2003
72 
-- prints out "Hello World"
73 
--
74 
-- Version 0.6 - 5 September 2003
75 
-- Runs SBUG
76 
--
77 
-- Version 1.0- 6 Sep 2003 - John Kent
78 
-- Inverted SysClk
79 
-- Initial release to Open Cores
80 
--
81 
-- Version 1.1 - 17 Jan 2004 - John Kent
82 
-- Updated miniUart.
83 
--
84 
-- Version 1.2 - 25 Jan 2004 - John Kent
85 
-- removed signals "test_alu" and "test_cc"
86 
-- Trap hardware re-instated.
87 
--
88 
-- Version 1.3 - 11 Feb 2004 - John Kent
89 
-- Designed forked off to produce System09_VDU
90 
-- Added VDU component
91 137 davidgb 
-- VDU runs at 25MHz and divides the clock by 2 for the CPU
92 128 davidgb 
-- UART Runs at 57.6 Kbps
93 
--
94 
-- Version 2.0 - 2 September 2004 - John Kent
95 
-- ported to Digilent Xilinx Spartan3 starter board
96 137 davidgb 
-- removed Compact Flash and Trap Logic.
97 128 davidgb 
-- Replaced SBUG with KBug9s
98 
--
99 
-- Version 3.0 - 29th August 2006 - John Kent
100 
-- Adapted to XSA-3S1000 board.
101 
-- Removed DAT and miniUART.
102 
-- Used 32KBytes of Block RAM.
103 
--
104 
-- Version 3.1 - 15th January 2007 - John Kent
105 
-- Modified vdu8 interface
106 
-- Added a clock divider
107 
--
108 
-- Version 3.2 - 25th February 2007 - John Kent
109 
-- reinstated ACIA_6850 and ACIA_Clock
110 
-- Updated VDU8 & Keyboard with generic parameters
111 
-- Defined Constants for clock speed calculations
112 
--
113 
-- Version 3.3 - 1st July 2007 - John Kent
114 
-- Made VDU mono to save on one RAMB16
115 
-- Used distributed memory for Key Map ROM to save one RAMB16
116 
-- Added Flex RAM at $C000 to $DFFF using 4 spare RAMB16s
117 
-- Added timer and trap logic
118 
-- Added IDE Interface for Compact Flash
119 
-- Replaced KBug9s and stack with Sys09Bug.
120 
--
121 
-- Version 4.0 - 1st February 2008 - John kent
122 
-- Replaced Block RAM with SDRAM Interface
123 
-- Modified Hold timing for SDRAM
124 
-- Added CF and Ethernet interface
125 
-- via the 16 bit peripheral bus at $E100
126 
--
127 
--===========================================================================--
128 
library ieee;
129 
   use ieee.std_logic_1164.all;
130 
   use IEEE.STD_LOGIC_ARITH.ALL;
131 
   use IEEE.STD_LOGIC_UNSIGNED.ALL;
132 
   use ieee.numeric_std.all;
133 
library work;
134 137 davidgb 
   use work.common.all;
135 
   use WORK.xsasdram.all;
136 128 davidgb 
library unisim;
137 
   use unisim.vcomponents.all;
138 
 
139 
entity system09 is
140 
  port(
141 
    CLKA         : in  Std_Logic;  -- 100MHz Clock input
142 
--    CLKB         : in  Std_Logic;  -- 50MHz Clock input
143 137 davidgb 
    SW2_N        : in  Std_logic;  -- Master Reset input (active low)
144 
    SW3_N        : in  Std_logic;  -- Non Maskable Interrupt input (active low)
145 128 davidgb 
 
146 137 davidgb 
    -- PS/2 Keyboard
147 
    ps2_clk      : inout Std_logic;
148 
    ps2_dat      : inout Std_Logic;
149 128 davidgb 
 
150 137 davidgb 
    -- CRTC output signals
151 
    vga_vsync_n  : out Std_Logic;
152 128 davidgb 
    vga_hsync_n  : out Std_Logic;
153 
    vga_blue     : out std_logic_vector(2 downto 0);
154 
    vga_green    : out std_logic_vector(2 downto 0);
155 
    vga_red      : out std_logic_vector(2 downto 0);
156 
 
157 
    -- RS232 Port
158 137 davidgb 
    RS232_RXD    : in  Std_Logic;
159 
    RS232_TXD    : out Std_Logic;
160 128 davidgb 
    RS232_CTS    : in  Std_Logic;
161 
    RS232_RTS    : out Std_Logic;
162 
 
163 137 davidgb 
    -- Status 7 segment LED
164 
    S            : out std_logic_vector(7 downto 0);
165 128 davidgb 
 
166 
    -- SDRAM side
167 
    SDRAM_clkfb  : in  std_logic;            -- feedback SDRAM clock after PCB delays
168 
    SDRAM_clkout : out std_logic;            -- clock to SDRAM
169 
    SDRAM_CKE    : out std_logic;            -- clock-enable to SDRAM
170 
    SDRAM_CS_N   : out std_logic;            -- chip-select to SDRAM
171 
    SDRAM_RAS_N  : out std_logic;            -- SDRAM row address strobe
172 
    SDRAM_CAS_N  : out std_logic;            -- SDRAM column address strobe
173 
    SDRAM_WE_N   : out std_logic;            -- SDRAM write enable
174 
    SDRAM_BA     : out std_logic_vector(1 downto 0);  -- SDRAM bank address
175 
    SDRAM_A      : out std_logic_vector(12 downto 0);  -- SDRAM row/column address
176 
    SDRAM_D      : inout  std_logic_vector(15 downto 0);  -- data from SDRAM
177 
    SDRAM_DQMH   : out std_logic;            -- enable upper-byte of SDRAM databus if true
178 
    SDRAM_DQML   : out std_logic;            -- enable lower-byte of SDRAM databus if true
179 
 
180 137 davidgb 
    -- Peripheral I/O bus $E100 - $E1FF
181 128 davidgb 
    PB_RD_N      : out std_logic;
182 
    PB_WR_N      : out std_logic;
183 
    PB_A         : out std_logic_vector(4 downto 0);
184 
    PB_D         : inout std_logic_vector(15 downto 0);
185 
 
186 
    -- IDE Compact Flash $E100 - $E13F
187 
    ide_dmack_n  : out std_logic;
188 137 davidgb 
    ide_cs0_n    : out std_logic;
189 
    ide_cs1_n    : out std_logic;
190 128 davidgb 
 
191 
    -- Ethernet $E140 - $E17F
192 
    ether_cs_n   : out std_logic;
193 
    ether_aen    : out std_logic; -- Ethernet address enable not
194 
    ether_bhe_n  : out std_logic; -- Ethernet bus high enable
195 
    ether_clk    : in  std_logic; -- Ethernet clock
196 
    ether_rdy    : in  std_logic; -- Ethernet ready
197 
    ether_irq    : in  std_logic; -- Ethernet irq - Shared with BAR6
198 
 
199 
    -- Slot 1 $E180 - $E1BF
200 137 davidgb 
    slot1_cs_n   : out std_logic;
201 
--  slot1_irq    : in  std_logic;
202 128 davidgb 
 
203 
    -- Slot 2 $E1C0 - $E1FF
204 137 davidgb 
    slot2_cs_n   : out std_logic;
205 
--  slot2_irq    : in  std_logic;
206 140 davidgb 
 
207 128 davidgb 
-- CPU Debug Interface signals
208 
--    cpu_reset_o     : out Std_Logic;
209 
--    cpu_clk_o       : out Std_Logic;
210 
--    cpu_rw_o        : out std_logic;
211 
--    cpu_vma_o       : out std_logic;
212 
--    cpu_halt_o      : out std_logic;
213 
--    cpu_hold_o      : out std_logic;
214 
--    cpu_firq_o      : out std_logic;
215 
--    cpu_irq_o       : out std_logic;
216 
--    cpu_nmi_o       : out std_logic;
217 
--    cpu_addr_o      : out std_logic_vector(15 downto 0);
218 
--    cpu_data_in_o   : out std_logic_vector(7 downto 0);
219 
--    cpu_data_out_o  : out std_logic_vector(7 downto 0);
220 
 
221 137 davidgb 
    -- Disable Flash
222 
    FLASH_CE_N   : out std_logic
223 
    );
224 128 davidgb 
end system09;
225 
 
226 
-------------------------------------------------------------------------------
227 
-- Architecture for System09
228 
-------------------------------------------------------------------------------
229 
architecture rtl of system09 is
230 
 
231 
  -----------------------------------------------------------------------------
232 
  -- constants
233 140 davidgb 
  -----------------------------------------------------------------------------
234 
 
235 128 davidgb 
  -- SDRAM
236 
  constant MEM_CLK_FREQ         : natural := 100_000; -- operating frequency of Memory in KHz
237 
  constant SYS_CLK_DIV          : real    := 2.0;    -- divisor for FREQ (can only be 1.0, 1.5, 2.0, 2.5, 3.0, 4.0, 5.0, 8.0 or 16.0)
238 
  constant PIPE_EN              : boolean := false;  -- if true, enable pipelined read operations
239 
  constant MAX_NOP              : natural := 10000;  -- number of NOPs before entering self-refresh
240 
  constant MULTIPLE_ACTIVE_ROWS : boolean := false;  -- if true, allow an active row in each bank
241 
  constant DATA_WIDTH           : natural := 16;     -- host & SDRAM data width
242 
  constant NROWS                : natural := 8192;   -- number of rows in SDRAM array
243 
  constant NCOLS                : natural := 512;    -- number of columns in SDRAM array
244 
  constant HADDR_WIDTH          : natural := 24;     -- host-side address width
245 
  constant SADDR_WIDTH          : natural := 13;     -- SDRAM-side address width
246 
 
247 
  constant SYS_CLK_FREQ         : natural := ((MEM_CLK_FREQ*2)/integer(SYS_CLK_DIV*2.0))*1000;  -- FPGA System Clock
248 140 davidgb 
  constant CPU_CLK_FREQ         : natural := 25_000_000;  -- CPU Clock (Hz)
249 128 davidgb 
  constant CPU_CLK_DIV          : natural := (SYS_CLK_FREQ/CPU_CLK_FREQ);
250 
  constant VGA_CLK_FREQ         : natural := 25_000_000;  -- VGA Pixel Clock
251 
  constant VGA_CLK_DIV          : natural := ((MEM_CLK_FREQ*1000)/VGA_CLK_FREQ);
252 137 davidgb 
  constant BAUD_RATE            : integer := 57600;     -- Baud Rate
253 140 davidgb 
  constant ACIA_CLK_FREQ        : integer := BAUD_RATE * 16;
254 
 
255 
  constant TRESET               : natural := 300;      -- min initialization interval (us)
256 128 davidgb 
  constant RST_CYCLES           : natural := 1+(TRESET*(MEM_CLK_FREQ/1_000));  -- SDRAM power-on initialization interval
257 
 
258 
  type hold_state_type is ( hold_release_state, hold_request_state );
259 
 
260 
  -----------------------------------------------------------------------------
261 
  -- Signals
262 
  -----------------------------------------------------------------------------
263 
  -- BOOT ROM
264 
  signal rom_cs         : Std_logic;
265 
  signal rom_data_out   : Std_Logic_Vector(7 downto 0);
266 
 
267 
  -- Flex Memory & Monitor Stack
268 
  signal flex_cs        : Std_logic;
269 
  signal flex_data_out  : Std_Logic_Vector(7 downto 0);
270 
 
271 
  -- ACIA/UART Interface signals
272 
  signal acia_data_out  : Std_Logic_Vector(7 downto 0);
273 
  signal acia_cs        : Std_Logic;
274 
  signal acia_irq       : Std_Logic;
275 
  signal acia_clk       : Std_Logic;
276 
  signal rxd            : Std_Logic;
277 
  signal txd            : Std_Logic;
278 
  signal DCD_n          : Std_Logic;
279 
  signal RTS_n          : Std_Logic;
280 
  signal CTS_n          : Std_Logic;
281 
 
282 
  -- keyboard port
283 
  signal keyboard_data_out : std_logic_vector(7 downto 0);
284 
  signal keyboard_cs       : std_logic;
285 
  signal keyboard_irq      : std_logic;
286 
 
287 
  -- RAM
288 
  signal ram_cs         : std_logic; -- memory chip select
289 
  signal ram_data_out   : std_logic_vector(7 downto 0);
290 137 davidgb 
  signal ram_rd_req     : std_logic; -- ram read request (asynch set on ram read, cleared falling CPU clock edge)
291 128 davidgb 
  signal ram_wr_req     : std_logic; -- ram write request (set on rising CPU clock edge, asynch clear on acknowledge)
292 
  signal ram_hold       : std_logic; -- hold off slow accesses
293 
  signal ram_release    : std_logic; -- Release ram hold
294 
 
295 
  -- CPU Interface signals
296 
  signal cpu_reset      : Std_Logic;
297 
  signal cpu_clk        : Std_Logic;
298 
  signal cpu_rw         : std_logic;
299 
  signal cpu_vma        : std_logic;
300 
  signal cpu_halt       : std_logic;
301 
  signal cpu_hold       : std_logic;
302 
  signal cpu_firq       : std_logic;
303 
  signal cpu_irq        : std_logic;
304 
  signal cpu_nmi        : std_logic;
305 
  signal cpu_addr       : std_logic_vector(15 downto 0);
306 
  signal cpu_data_in    : std_logic_vector(7 downto 0);
307 
  signal cpu_data_out   : std_logic_vector(7 downto 0);
308 
 
309 
  -- Dynamic Address Translation
310 
  signal dat_cs       : std_logic;
311 
  signal dat_addr     : std_logic_vector(7 downto 0);
312 
 
313 
  -- Video Display Unit
314 
  signal vdu_cs         : std_logic;
315 
  signal vdu_data_out   : std_logic_vector(7 downto 0);
316 
  signal vga_red_o      : std_logic;
317 
  signal vga_green_o    : std_logic;
318 
  signal vga_blue_o     : std_logic;
319 
 
320 
  -- timer
321 
  signal timer_data_out : std_logic_vector(7 downto 0);
322 
  signal timer_cs       : std_logic;
323 
  signal timer_irq      : std_logic;
324 
 
325 
  -- trap
326 
  signal trap_cs        : std_logic;
327 
  signal trap_data_out  : std_logic_vector(7 downto 0);
328 
  signal trap_irq       : std_logic;
329 
 
330 
  -- Peripheral Bus port
331 
  signal pb_data_out   : std_logic_vector(7 downto 0);
332 137 davidgb 
  signal pb_cs         : std_logic;   -- peripheral bus chip select
333 
  signal pb_wru        : std_logic;   -- upper byte write strobe
334 
  signal pb_wrl        : std_logic;   -- lower byte write strobe
335 
  signal pb_rdu        : std_logic;   -- upper byte read strobe
336 
  signal pb_rdl        : std_logic;   -- lower byte read strobe
337 
  signal pb_hold       : std_logic;   -- hold peripheral bus access
338 
  signal pb_release    : std_logic;   -- release hold of peripheral bus
339 128 davidgb 
  signal pb_count      : std_logic_vector(3 downto 0); -- hold counter
340 
  signal pb_hold_state : hold_state_type;
341 
  signal pb_wreg       : std_logic_vector(7 downto 0); -- lower byte write register
342 
  signal pb_rreg       : std_logic_vector(7 downto 0); -- lower byte read register
343 
 
344 
  -- Peripheral chip selects on Peripheral Bus
345 
  signal ide_cs        : std_logic; -- IDE CF interface
346 137 davidgb 
  signal ether_cs      : std_logic; -- Ethernet interface
347 
  signal slot1_cs      : std_logic; -- Expansion slot 1
348 
  signal slot2_cs      : std_logic; -- Expansion slot 2
349 128 davidgb 
 
350 
  signal rst_i         : std_logic;     -- internal reset signal
351 
  signal clk_i         : std_logic;     -- internal master clock signal
352 
  signal lock          : std_logic;     -- SDRAM clock DLL lock indicator
353 
 
354 
  -- signals that go through the SDRAM host-side interface
355 
  signal opBegun       : std_logic;        -- SDRAM operation started indicator
356 
  signal earlyBegun    : std_logic;        -- SDRAM operation started indicator
357 
  signal ramDone       : std_logic;        -- SDRAM operation complete indicator
358 
  signal rdDone        : std_logic;        -- SDRAM read operation complete indicator
359 
  signal wrDone        : std_logic;        -- SDRAM write operation complete indicator
360 
  signal hAddr         : std_logic_vector(HADDR_WIDTH-1 downto 0);  -- host address bus
361 
  signal hDIn          : std_logic_vector(DATA_WIDTH-1 downto 0);  -- host-side data to SDRAM
362 
  signal hDOut         : std_logic_vector(DATA_WIDTH-1 downto 0);  -- host-side data from SDRAM
363 
  signal hRd           : std_logic;        -- host-side read control signal
364 
  signal hWr           : std_logic;        -- host-side write control signal
365 140 davidgb 
  signal hUds          : std_logic;        -- host-side upper data strobe
366 
  signal hLds          : std_logic;        -- host-side lower data strobe
367 128 davidgb 
  signal rdPending     : std_logic;        -- read operation pending in SDRAM pipeline
368 140 davidgb 
  type ram_type is (ram_state_0,
369 
                    ram_state_rd1, ram_state_rd2,
370 
                    ram_state_wr1,
371 137 davidgb 
                    ram_state_3 );
372 128 davidgb 
  signal ram_state     : ram_type;
373 
 
374 140 davidgb 
 
375 128 davidgb 
--  signal BaudCount   : std_logic_vector(5 downto 0);
376 
  signal CountL        : std_logic_vector(23 downto 0);
377 
  signal clk_count     : natural range 0 to CPU_CLK_DIV;
378 
  signal Clk25         : std_logic;
379 
  signal vga_clk       : std_logic;
380 
 
381 
-----------------------------------------------------------------
382 
--
383 
-- CPU09 CPU core
384 
--
385 
-----------------------------------------------------------------
386 
 
387 
component cpu09
388 
  port (
389 137 davidgb 
    clk:      in  std_logic;
390 
    rst:      in  std_logic;
391 
    vma:      out std_logic;
392 
    addr:     out std_logic_vector(15 downto 0);
393 
    rw:       out std_logic;     -- Asynchronous memory interface
394 
    data_out: out std_logic_vector(7 downto 0);
395 
    data_in:  in  std_logic_vector(7 downto 0);
396 
    irq:      in  std_logic;
397 
    firq:     in  std_logic;
398 
    nmi:      in  std_logic;
399 
    halt:     in  std_logic;
400 
    hold:     in  std_logic
401 128 davidgb 
  );
402 
end component;
403 
 
404 
 
405 
----------------------------------------
406 
--
407 
-- 4K Block RAM Monitor ROM
408 
--
409 
----------------------------------------
410 
component mon_rom
411 
    Port (
412 
       clk   : in  std_logic;
413 137 davidgb 
       rst   : in  std_logic;
414 
       cs    : in  std_logic;
415 
       rw    : in  std_logic;
416 128 davidgb 
       addr  : in  std_logic_vector (11 downto 0);
417 
       data_out : out std_logic_vector (7 downto 0);
418 
       data_in : in  std_logic_vector (7 downto 0)
419 
    );
420 
end component;
421 
 
422 
 
423 
----------------------------------------
424 
--
425 
-- 8KBytes Block RAM for FLEX9
426 
-- $C000 - $DFFF
427 
--
428 
----------------------------------------
429 
component flex_ram
430 
  Port (
431 
    clk      : in  std_logic;
432 
    rst      : in  std_logic;
433 
    cs       : in  std_logic;
434 
    rw       : in  std_logic;
435 
    addr     : in  std_logic_vector (12 downto 0);
436 
    data_out    : out std_logic_vector (7 downto 0);
437 
    data_in    : in  std_logic_vector (7 downto 0)
438 
    );
439 
end component;
440 
 
441 
-----------------------------------------------------------------
442 
--
443 
-- 6850 Compatible ACIA / UART
444 
--
445 
-----------------------------------------------------------------
446 
 
447 
component acia6850
448 
  port (
449 
     clk      : in  Std_Logic;  -- System Clock
450 
     rst      : in  Std_Logic;  -- Reset input (active high)
451 
     cs       : in  Std_Logic;  -- miniUART Chip Select
452 
     rw       : in  Std_Logic;  -- Read / Not Write
453 
     addr     : in  Std_Logic;  -- Register Select
454 
     data_in  : in  Std_Logic_Vector(7 downto 0); -- Data Bus In
455 
     data_out : out Std_Logic_Vector(7 downto 0); -- Data Bus Out
456 
     irq      : out Std_Logic;  -- Interrupt
457 
     RxC      : in  Std_Logic;  -- Receive Baud Clock
458 
     TxC      : in  Std_Logic;  -- Transmit Baud Clock
459 
     RxD      : in  Std_Logic;  -- Receive Data
460 
     TxD      : out Std_Logic;  -- Transmit Data
461 
     DCD_n    : in  Std_Logic;  -- Data Carrier Detect
462 
     CTS_n    : in  Std_Logic;  -- Clear To Send
463 
     RTS_n    : out Std_Logic );  -- Request To send
464 
end component;
465 
 
466 
 
467 
-----------------------------------------------------------------
468 
--
469 
-- ACIA Clock divider
470 
--
471 
-----------------------------------------------------------------
472 
 
473 
component ACIA_Clock
474 
  generic (
475 
     SYS_CLK_FREQ  : integer :=  SYS_CLK_FREQ;
476 137 davidgb 
     ACIA_CLK_FREQ : integer := ACIA_CLK_FREQ
477 128 davidgb 
  );
478 
  port (
479 
     clk      : in  Std_Logic;  -- System Clock Input
480 137 davidgb 
     ACIA_clk : out Std_logic   -- ACIA Clock output
481 128 davidgb 
  );
482 
end component;
483 
 
484 
 
485 
----------------------------------------
486 
--
487 
-- PS/2 Keyboard
488 
--
489 
----------------------------------------
490 
 
491 
component keyboard
492 
  generic(
493 
  KBD_CLK_FREQ : integer := CPU_CLK_FREQ
494 
  );
495 
  port(
496 
  clk             : in    std_logic;
497 
  rst             : in    std_logic;
498 
  cs              : in    std_logic;
499 
  rw              : in    std_logic;
500 
  addr            : in    std_logic;
501 
  data_in         : in    std_logic_vector(7 downto 0);
502 
  data_out        : out   std_logic_vector(7 downto 0);
503 
  irq             : out   std_logic;
504 
  kbd_clk         : inout std_logic;
505 
  kbd_data        : inout std_logic
506 
  );
507 
end component;
508 
 
509 
----------------------------------------
510 
--
511 
-- Video Display Unit.
512 
--
513 
----------------------------------------
514 
component vdu8
515 
      generic(
516 
        VDU_CLK_FREQ           : integer := CPU_CLK_FREQ; -- HZ
517 
        VGA_CLK_FREQ           : integer := VGA_CLK_FREQ; -- HZ
518 137 davidgb 
        VGA_HOR_CHARS          : integer := 80; -- CHARACTERS
519 
        VGA_VER_CHARS          : integer := 25; -- CHARACTERS
520 
        VGA_PIX_PER_CHAR       : integer := 8;  -- PIXELS
521 
        VGA_LIN_PER_CHAR       : integer := 16; -- LINES
522 
        VGA_HOR_BACK_PORCH     : integer := 40; -- PIXELS
523 
        VGA_HOR_SYNC           : integer := 96; -- PIXELS
524 
        VGA_HOR_FRONT_PORCH    : integer := 24; -- PIXELS
525 
        VGA_VER_BACK_PORCH     : integer := 13; -- LINES
526 
        VGA_VER_SYNC           : integer := 2;  -- LINES
527 
        VGA_VER_FRONT_PORCH    : integer := 35  -- LINES
528 128 davidgb 
      );
529 
      port(
530 137 davidgb 
      -- control register interface
531 
      vdu_clk      : in  std_logic;  -- CPU Clock - 25MHz
532 128 davidgb 
      vdu_rst      : in  std_logic;
533 137 davidgb 
      vdu_cs       : in  std_logic;
534 
      vdu_rw       : in  std_logic;
535 
      vdu_addr     : in  std_logic_vector(2 downto 0);
536 128 davidgb 
      vdu_data_in  : in  std_logic_vector(7 downto 0);
537 
      vdu_data_out : out std_logic_vector(7 downto 0);
538 
 
539 
      -- vga port connections
540 137 davidgb 
      vga_clk      : in  std_logic; -- VGA Pixel Clock - 25 MHz
541 128 davidgb 
      vga_red_o    : out std_logic;
542 
      vga_green_o  : out std_logic;
543 
      vga_blue_o   : out std_logic;
544 
      vga_hsync_o  : out std_logic;
545 
      vga_vsync_o  : out std_logic
546 
   );
547 
end component;
548 
 
549 
 
550 
----------------------------------------
551 
--
552 
-- Timer module
553 
--
554 
----------------------------------------
555 
 
556 
component timer
557 
  port (
558 
     clk       : in std_logic;
559 
     rst       : in std_logic;
560 
     cs        : in std_logic;
561 
     rw        : in std_logic;
562 
     addr      : in std_logic;
563 
     data_in   : in std_logic_vector(7 downto 0);
564 137 davidgb 
     data_out  : out std_logic_vector(7 downto 0);
565 
     irq       : out std_logic
566 
     );
567 128 davidgb 
end component;
568 
 
569 
------------------------------------------------------------
570 
--
571 
-- Bus Trap logic
572 
--
573 
------------------------------------------------------------
574 
 
575 
component trap
576 137 davidgb 
   port (
577 
    clk        : in  std_logic;
578 128 davidgb 
    rst        : in  std_logic;
579 
    cs         : in  std_logic;
580 
    rw         : in  std_logic;
581 
    vma        : in  std_logic;
582 
    addr       : in  std_logic_vector(15 downto 0);
583 
    data_in    : in  std_logic_vector(7 downto 0);
584 137 davidgb 
    data_out   : out std_logic_vector(7 downto 0);
585 
    irq        : out std_logic
586 128 davidgb 
  );
587 
end component;
588 
 
589 
 
590 
----------------------------------------
591 
--
592 
-- Dynamic Address Translation Registers
593 
--
594 
----------------------------------------
595 
component dat_ram
596 
  port (
597 
    clk      : in  std_logic;
598 137 davidgb 
    rst      : in  std_logic;
599 
    cs       : in  std_logic;
600 
    rw       : in  std_logic;
601 
    addr_lo  : in  std_logic_vector(3 downto 0);
602 
    addr_hi  : in  std_logic_vector(3 downto 0);
603 128 davidgb 
    data_in  : in  std_logic_vector(7 downto 0);
604 137 davidgb 
    data_out : out std_logic_vector(7 downto 0)
605 128 davidgb 
  );
606 
end component;
607 
 
608 140 davidgb 
 
609 128 davidgb 
component XSASDRAMCntl
610 
  generic(
611 
    FREQ                 :     natural := MEM_CLK_FREQ;-- operating frequency in KHz
612 
    CLK_DIV              :     real    := SYS_CLK_DIV; -- divisor for FREQ (can only be 1.0, 1.5, 2.0, 2.5, 3.0, 4.0, 5.0, 8.0 or 16.0)
613 
    PIPE_EN              :     boolean := PIPE_EN;     -- if true, enable pipelined read operations
614 
    MAX_NOP              :     natural := MAX_NOP;     -- number of NOPs before entering self-refresh
615 
    MULTIPLE_ACTIVE_ROWS :     boolean := MULTIPLE_ACTIVE_ROWS;  -- if true, allow an active row in each bank
616 
    DATA_WIDTH           :     natural := DATA_WIDTH;  -- host & SDRAM data width
617 
    NROWS                :     natural := NROWS;       -- number of rows in SDRAM array
618 
    NCOLS                :     natural := NCOLS;       -- number of columns in SDRAM array
619 
    HADDR_WIDTH          :     natural := HADDR_WIDTH; -- host-side address width
620 
    SADDR_WIDTH          :     natural := SADDR_WIDTH  -- SDRAM-side address width
621 
    );
622 
  port(
623 
    -- host side
624 
    clk                  : in  std_logic;  -- master clock
625 
    bufclk               : out std_logic;  -- buffered master clock
626 
    clk1x                : out std_logic;  -- host clock sync'ed to master clock (and divided if CLK_DIV>1)
627 
    clk2x                : out std_logic;  -- double-speed host clock
628 
    lock                 : out std_logic;  -- true when host clock is locked to master clock
629 
    rst                  : in  std_logic;  -- reset
630 
    rd                   : in  std_logic;  -- initiate read operation
631 
    wr                   : in  std_logic;  -- initiate write operation
632 140 davidgb 
    uds                  : in  std_logic;  -- upper data strobe
633 
    lds                  : in  std_logic;  -- lower data strobe
634 128 davidgb 
    earlyOpBegun         : out std_logic;  -- read/write/self-refresh op begun     (async)
635 
    opBegun              : out std_logic;  -- read/write/self-refresh op begun (clocked)
636 
    rdPending            : out std_logic;  -- read operation(s) are still in the pipeline
637 
    done                 : out std_logic;  -- read or write operation is done
638 
    rdDone               : out std_logic;  -- read done and data is available
639 
    hAddr                : in  std_logic_vector(HADDR_WIDTH-1 downto 0);  -- address from host
640 
    hDIn                 : in  std_logic_vector(DATA_WIDTH-1 downto 0);  -- data from host
641 
    hDOut                : out std_logic_vector(DATA_WIDTH-1 downto 0);  -- data to host
642 
    status               : out std_logic_vector(3 downto 0);  -- diagnostic status of the FSM
643 
 
644 
    -- SDRAM side
645 
    sclkfb               : in    std_logic;           -- clock from SDRAM after PCB delays
646 
    sclk                 : out   std_logic;           -- SDRAM clock sync'ed to master clock
647 
    cke                  : out   std_logic;           -- clock-enable to SDRAM
648 
    cs_n                 : out   std_logic;           -- chip-select to SDRAM
649 
    ras_n                : out   std_logic;           -- SDRAM row address strobe
650 
    cas_n                : out   std_logic;           -- SDRAM column address strobe
651 
    we_n                 : out   std_logic;           -- SDRAM write enable
652 
    ba                   : out   std_logic_vector(1 downto 0);  -- SDRAM bank address bits
653 
    sAddr                : out   std_logic_vector(SADDR_WIDTH-1 downto 0);  -- SDRAM row/column address
654 
    sData                : inout std_logic_vector(DATA_WIDTH-1 downto 0);  -- SDRAM in/out databus
655 
    dqmh                 : out   std_logic;           -- high databits I/O mask
656 
    dqml                 : out   std_logic            -- low databits I/O mask
657 
    );
658 
end component;
659 140 davidgb 
 
660 128 davidgb 
--
661 
-- Clock buffer
662 
--
663 
component BUFG
664 
   Port (
665 
     i: in std_logic;
666 137 davidgb 
     o: out std_logic
667 128 davidgb 
  );
668 
end component;
669 
 
670 
begin
671 
  -----------------------------------------------------------------------------
672 
  -- Instantiation of internal components
673 
  -----------------------------------------------------------------------------
674 
 
675 
my_cpu : cpu09  port map (
676 137 davidgb 
    clk       => cpu_clk,
677 128 davidgb 
    rst       => cpu_reset,
678 
    vma       => cpu_vma,
679 
    addr      => cpu_addr(15 downto 0),
680 137 davidgb 
    rw        => cpu_rw,
681 
    data_out  => cpu_data_out,
682 128 davidgb 
    data_in   => cpu_data_in,
683 137 davidgb 
    irq       => cpu_irq,
684 
    firq      => cpu_firq,
685 
    nmi       => cpu_nmi,
686 
    halt      => cpu_halt,
687 
    hold      => cpu_hold
688 128 davidgb 
  );
689 
 
690 
my_rom : mon_rom port map (
691 
       clk   => cpu_clk,
692 137 davidgb 
       rst   => cpu_reset,
693 
       cs    => rom_cs,
694 
       rw    => '1',
695 128 davidgb 
       addr  => cpu_addr(11 downto 0),
696 
       data_in => cpu_data_out,
697 
       data_out => rom_data_out
698 
    );
699 
 
700 
my_flex : flex_ram port map (
701 
    clk       => cpu_clk,
702 
    rst       => cpu_reset,
703 137 davidgb 
    cs        => flex_cs,
704 
    rw        => cpu_rw,
705 128 davidgb 
    addr      => cpu_addr(12 downto 0),
706 
    data_out     => flex_data_out,
707 
    data_in     => cpu_data_out
708 
    );
709 
 
710 
my_acia  : acia6850 port map (
711 137 davidgb 
    clk       => cpu_clk,
712 
    rst       => cpu_reset,
713 128 davidgb 
    cs        => acia_cs,
714 137 davidgb 
    rw        => cpu_rw,
715 128 davidgb 
    addr      => cpu_addr(0),
716 137 davidgb 
    data_in   => cpu_data_out,
717 
    data_out  => acia_data_out,
718 128 davidgb 
    irq       => acia_irq,
719 137 davidgb 
    RxC       => acia_clk,
720 
    TxC       => acia_clk,
721 
    RxD       => rxd,
722 
    TxD       => txd,
723 
    DCD_n     => dcd_n,
724 
    CTS_n     => cts_n,
725 
    RTS_n     => rts_n
726 
    );
727 128 davidgb 
 
728 
 
729 
my_ACIA_Clock : ACIA_Clock
730 
  generic map(
731 
    SYS_CLK_FREQ  =>  SYS_CLK_FREQ,
732 137 davidgb 
    ACIA_CLK_FREQ => ACIA_CLK_FREQ
733 128 davidgb 
  )
734 
  port map(
735 
    clk        => Clk_i,
736 
    acia_clk   => acia_clk
737 
  );
738 
 
739 
----------------------------------------
740 
--
741 
-- PS/2 Keyboard Interface
742 
--
743 
----------------------------------------
744 
my_keyboard : keyboard
745 
   generic map (
746 137 davidgb 
   KBD_CLK_FREQ => CPU_CLK_FREQ
747 
   )
748 128 davidgb 
   port map(
749 137 davidgb 
   clk          => cpu_clk,
750 
   rst          => cpu_reset,
751 
   cs           => keyboard_cs,
752 
   rw           => cpu_rw,
753 
   addr         => cpu_addr(0),
754 
   data_in      => cpu_data_out(7 downto 0),
755 
   data_out     => keyboard_data_out(7 downto 0),
756 
   irq          => keyboard_irq,
757 
   kbd_clk      => ps2_clk,
758 
   kbd_data     => ps2_dat
759 
   );
760 128 davidgb 
 
761 
----------------------------------------
762 
--
763 
-- Video Display Unit instantiation
764 
--
765 
----------------------------------------
766 
my_vdu : vdu8
767 
  generic map(
768 
      VDU_CLK_FREQ           => CPU_CLK_FREQ, -- HZ
769 
      VGA_CLK_FREQ           => VGA_CLK_FREQ, -- HZ
770 137 davidgb 
      VGA_HOR_CHARS          => 80, -- CHARACTERS
771 
      VGA_VER_CHARS          => 25, -- CHARACTERS
772 
      VGA_PIX_PER_CHAR       => 8,  -- PIXELS
773 
      VGA_LIN_PER_CHAR       => 16, -- LINES
774 
      VGA_HOR_BACK_PORCH     => 40, -- PIXELS
775 
      VGA_HOR_SYNC           => 96, -- PIXELS
776 
      VGA_HOR_FRONT_PORCH    => 24, -- PIXELS
777 
      VGA_VER_BACK_PORCH     => 13, -- LINES
778 
      VGA_VER_SYNC           => 2,  -- LINES
779 
      VGA_VER_FRONT_PORCH    => 35  -- LINES
780 128 davidgb 
  )
781 
  port map(
782 
 
783 137 davidgb 
      -- Control Registers
784 
      vdu_clk       => cpu_clk,               -- 12.5 MHz System Clock in
785 128 davidgb 
      vdu_rst       => cpu_reset,
786 137 davidgb 
      vdu_cs        => vdu_cs,
787 
      vdu_rw        => cpu_rw,
788 
      vdu_addr      => cpu_addr(2 downto 0),
789 
      vdu_data_in   => cpu_data_out,
790 
      vdu_data_out  => vdu_data_out,
791 128 davidgb 
 
792 
      -- vga port connections
793 137 davidgb 
      vga_clk       => vga_clk,               -- 25 MHz VDU pixel clock
794 128 davidgb 
      vga_red_o     => vga_red_o,
795 
      vga_green_o   => vga_green_o,
796 
      vga_blue_o    => vga_blue_o,
797 
      vga_hsync_o   => vga_hsync_n,
798 
      vga_vsync_o   => vga_vsync_n
799 
   );
800 
 
801 
----------------------------------------
802 
--
803 
-- Timer Module
804 
--
805 
----------------------------------------
806 
my_timer  : timer port map (
807 
    clk       => cpu_clk,
808 137 davidgb 
    rst       => cpu_reset,
809 128 davidgb 
    cs        => timer_cs,
810 137 davidgb 
    rw        => cpu_rw,
811 128 davidgb 
    addr      => cpu_addr(0),
812 137 davidgb 
    data_in   => cpu_data_out,
813 
    data_out  => timer_data_out,
814 128 davidgb 
    irq       => timer_irq
815 
    );
816 
 
817 
----------------------------------------
818 
--
819 
-- Bus Trap Interrupt logic
820 
--
821 
----------------------------------------
822 137 davidgb 
my_trap : trap port map (
823 
    clk        => cpu_clk,
824 128 davidgb 
    rst        => cpu_reset,
825 
    cs         => trap_cs,
826 
    rw         => cpu_rw,
827 137 davidgb 
    vma        => cpu_vma,
828 128 davidgb 
    addr       => cpu_addr,
829 
    data_in    => cpu_data_out,
830 137 davidgb 
    data_out   => trap_data_out,
831 
    irq        => trap_irq
832 128 davidgb 
    );
833 
 
834 
 
835 
my_dat : dat_ram port map (
836 
    clk       => cpu_clk,
837 137 davidgb 
    rst       => cpu_reset,
838 
    cs        => dat_cs,
839 
    rw        => cpu_rw,
840 
    addr_hi   => cpu_addr(15 downto 12),
841 
    addr_lo   => cpu_addr(3 downto 0),
842 128 davidgb 
    data_in   => cpu_data_out,
843 137 davidgb 
    data_out  => dat_addr(7 downto 0)
844 
    );
845 140 davidgb 
 
846 128 davidgb 
  ------------------------------------------------------------------------
847 
  -- Instantiate the SDRAM controller that connects to the memory tester
848 
  -- module and interfaces to the external SDRAM chip.
849 
  ------------------------------------------------------------------------
850 
  u1 : xsaSDRAMCntl
851 
    generic map(
852 140 davidgb 
      FREQ                 => MEM_CLK_FREQ,
853 137 davidgb 
      CLK_DIV              => SYS_CLK_DIV,
854 140 davidgb 
      PIPE_EN              => PIPE_EN,
855 137 davidgb 
      MAX_NOP              => MAX_NOP,
856 128 davidgb 
      MULTIPLE_ACTIVE_ROWS => MULTIPLE_ACTIVE_ROWS,
857 
      DATA_WIDTH           => DATA_WIDTH,
858 
      NROWS                => NROWS,
859 
      NCOLS                => NCOLS,
860 
      HADDR_WIDTH          => HADDR_WIDTH,
861 
      SADDR_WIDTH          => SADDR_WIDTH
862 
      )
863 
    port map(
864 137 davidgb 
      -- Host Side
865 128 davidgb 
      clk                  => CLKA,     -- master clock from external clock source (unbuffered)
866 
      bufclk               => open,     -- buffered master clock output
867 
      clk1x                => clk_i,    -- synchronized master clock (accounts for delays to external SDRAM)
868 
      clk2x                => open,     -- synchronized doubled master clock
869 
      lock                 => lock,     -- DLL lock indicator
870 
      rst                  => rst_i,    -- reset
871 
      rd                   => hRd,      -- host-side SDRAM read control from memory tester
872 
      wr                   => hWr,      -- host-side SDRAM write control from memory tester
873 140 davidgb 
      uds                  => hUds,     -- host-side SDRAM upper data strobe
874 
      lds                  => hLds,     -- host-side SDRAM lower data strobe
875 128 davidgb 
      rdPending            => rdPending,-- read operation to SDRAM is in progress
876 
      opBegun              => opBegun,  -- indicates memory read/write has begun
877 
      earlyOpBegun         => earlyBegun,  -- early indicator that memory operation has begun
878 
      rdDone               => rdDone,   -- indicates SDRAM memory read operation is done
879 
      done                 => ramDone, -- indicates SDRAM memory read or write operation is done
880 
      hAddr                => hAddr,    -- host-side address from memory tester to SDRAM
881 
      hDIn                 => hDIn,     -- test data pattern from memory tester to SDRAM
882 
      hDOut                => hDOut,    -- SDRAM data output to memory tester
883 
      status               => open,     -- SDRAM controller state (for diagnostics)
884 137 davidgb 
      -- SDRAM Side
885 128 davidgb 
      sclkfb               => SDRAM_clkfb,    -- clock feedback with added external PCB delays
886 
      sclk                 => SDRAM_clkout,   -- synchronized clock to external SDRAM
887 
      cke                  => SDRAM_cke,      -- SDRAM clock enable
888 
      cs_n                 => SDRAM_cs_n,     -- SDRAM chip-select
889 
      ras_n                => SDRAM_ras_n,    -- SDRAM RAS
890 
      cas_n                => SDRAM_cas_n,    -- SDRAM CAS
891 
      we_n                 => SDRAM_we_n,     -- SDRAM write-enable
892 
      ba                   => SDRAM_ba,       -- SDRAM bank address
893 
      sAddr                => SDRAM_A,        -- SDRAM address
894 
      sData                => SDRAM_D,        -- SDRAM databus
895 
      dqmh                 => SDRAM_dqmh,     -- SDRAM DQMH
896 
      dqml                 => SDRAM_dqml      -- SDRAM DQML
897 
      );
898 140 davidgb 
 
899 128 davidgb 
cpu_clk_buffer : BUFG port map(
900 
    i => Clk25,
901 137 davidgb 
    o => cpu_clk
902 
    );
903 128 davidgb 
 
904 
vga_clk_buffer : BUFG port map(
905 
    i => Clk25,
906 137 davidgb 
    o => vga_clk
907 
    );
908 
 
909 128 davidgb 
----------------------------------------------------------------------
910 
--
911 
-- Process to decode memory map
912 
--
913 
----------------------------------------------------------------------
914 
 
915 
mem_decode: process( cpu_addr, cpu_rw, cpu_vma,
916 137 davidgb 
                     dat_addr,
917 
                     rom_data_out,
918 
                     flex_data_out,
919 
                     acia_data_out,
920 
                     keyboard_data_out,
921 
                     vdu_data_out,
922 
                     pb_data_out,
923 
                     timer_data_out,
924 
                     trap_data_out,
925 
                     ram_data_out
926 
                     )
927 128 davidgb 
begin
928 
      cpu_data_in <= (others=>'0');
929 
      dat_cs      <= '0';
930 
      rom_cs      <= '0';
931 
      flex_cs     <= '0';
932 137 davidgb 
      acia_cs     <= '0';
933 
      keyboard_cs <= '0';
934 
      vdu_cs      <= '0';
935 
      timer_cs    <= '0';
936 
      trap_cs     <= '0';
937 
      pb_cs       <= '0';
938 
      ide_cs      <= '0';
939 
      ether_cs    <= '0';
940 
      slot1_cs    <= '0';
941 
      slot2_cs    <= '0';
942 
      ram_cs      <= '0';
943 128 davidgb 
      if cpu_addr( 15 downto 8 ) = "11111111" then
944 137 davidgb 
         cpu_data_in <= rom_data_out;
945 128 davidgb 
         dat_cs      <= cpu_vma;              -- write DAT
946 
         rom_cs      <= cpu_vma;              -- read  ROM
947 137 davidgb 
      --
948 
      -- Sys09Bug Monitor ROM $F000 - $FFFF
949 
      --
950 
      elsif dat_addr(3 downto 0) = "1111" then -- $XF000 - $XFFFF
951 
         cpu_data_in <= rom_data_out;
952 
         rom_cs      <= cpu_vma;
953 128 davidgb 
 
954 
      --
955 137 davidgb 
      -- IO Devices $E000 - $E7FF
956 
      --
957 
      elsif dat_addr(3 downto 0) = "1110" then -- $XE000 - $XEFFF
958 
         case cpu_addr(11 downto 8) is
959 
         --
960 
         -- SWTPC peripherals from $E000 to $E0FF
961 
         --
962 
         when "0000" =>
963 
           case cpu_addr(7 downto 4) is
964 
           --
965 
           -- Console Port ACIA $E000 - $E00F
966 
           --
967 
           when "0000" => -- $E000
968 
             cpu_data_in <= acia_data_out;
969 
             acia_cs     <= cpu_vma;
970 128 davidgb 
 
971 
           --
972 
           -- Reserved
973 137 davidgb 
           -- Floppy Disk Controller port $E010 - $E01F
974 
           --
975 128 davidgb 
 
976 
           --
977 
           -- Keyboard port $E020 - $E02F
978 137 davidgb 
           --
979 
           when "0010" => -- $E020
980 128 davidgb 
             cpu_data_in <= keyboard_data_out;
981 137 davidgb 
             keyboard_cs <= cpu_vma;
982 128 davidgb 
 
983 
           --
984 
           -- VDU port $E030 - $E03F
985 137 davidgb 
           --
986 
           when "0011" => -- $E030
987 128 davidgb 
             cpu_data_in <= vdu_data_out;
988 137 davidgb 
             vdu_cs      <= cpu_vma;
989 128 davidgb 
 
990 
           --
991 137 davidgb 
           -- Reserved SWTPc MP-T Timer $E040 - $E04F
992 
           --
993 
           when "0100" => -- $E040
994 128 davidgb 
             cpu_data_in <= (others=> '0');
995 
 
996 
           --
997 
           -- Timer $E050 - $E05F
998 137 davidgb 
           --
999 
           when "0101" => -- $E050
1000 128 davidgb 
             cpu_data_in <= timer_data_out;
1001 
             timer_cs    <= cpu_vma;
1002 
 
1003 
           --
1004 
           -- Bus Trap Logic $E060 - $E06F
1005 137 davidgb 
           --
1006 
           when "0110" => -- $E060
1007 128 davidgb 
             cpu_data_in <= trap_data_out;
1008 137 davidgb 
             trap_cs     <= cpu_vma;
1009 128 davidgb 
 
1010 
           --
1011 137 davidgb 
           -- Reserved SWTPc MP-ID PIA Timer/Printer Port $E080 - $E08F
1012 
           --
1013 128 davidgb 
 
1014 
           --
1015 137 davidgb 
           -- Reserved SWTPc MP-ID PTM 6840 Timer Port $E090 - $E09F
1016 
           --
1017 128 davidgb 
 
1018 
           --
1019 137 davidgb 
           -- Remaining 6 slots reserved for non SWTPc Peripherals
1020 
           --
1021 
           when others => -- $E0A0 to $E0FF
1022 
             null;
1023 
           end case;
1024 
         --
1025 
         -- XST-3.0 Peripheral Bus goes here
1026 
         -- $E100 to $E1FF
1027 
         -- Four devices
1028 
         -- IDE, Ethernet, Slot1, Slot2
1029 
         --
1030 
         when "0001" =>
1031 
           cpu_data_in <= pb_data_out;
1032 
           pb_cs       <= cpu_vma;
1033 
           case cpu_addr(7 downto 6) is
1034 
           --
1035 
           -- IDE Interface $E100 to $E13F
1036 
           --
1037 
           when "00" =>
1038 
             ide_cs   <= cpu_vma;
1039 
           --
1040 
           -- Ethernet Interface $E140 to $E17F
1041 
           --
1042 
           when "01" =>
1043 
             ether_cs <= cpu_vma;
1044 
           --
1045 
           -- Slot 1 Interface $E180 to $E1BF
1046 
           --
1047 
           when "10" =>
1048 
             slot1_cs <= cpu_vma;
1049 
           --
1050 
           -- Slot 2 Interface $E1C0 to $E1FF
1051 
           --
1052 
           when "11" =>
1053 
             slot2_cs <= cpu_vma;
1054 
           --
1055 
           -- Nothing else
1056 
           --
1057 128 davidgb 
           when others =>
1058 137 davidgb 
             null;
1059 128 davidgb 
           end case;
1060 
         --
1061 137 davidgb 
         -- $E200 to $EFFF reserved for future use
1062 
         --
1063 
         when others =>
1064 
           null;
1065 128 davidgb 
         end case;
1066 137 davidgb 
      --
1067 
      -- Flex RAM $0C000 - $0DFFF
1068 
      --
1069 
      elsif dat_addr(7 downto 1) = "0000110" then -- $0C000 - $0DFFF
1070 
         cpu_data_in <= flex_data_out;
1071 
         flex_cs     <= cpu_vma;
1072 
      --
1073 
      -- Everything else is RAM
1074 
      --
1075 
      else
1076 
         cpu_data_in <= ram_data_out;
1077 
         ram_cs      <= cpu_vma;
1078 
     end if;
1079 128 davidgb 
end process;
1080 
 
1081 
 
1082 
--
1083 
-- 16-bit Peripheral Bus
1084 
-- 6809 Big endian
1085 
-- ISA bus little endian
1086 
-- Not sure about IDE interface
1087 
--
1088 140 davidgb 
peripheral_bus: process( clk_i, cpu_reset, cpu_rw, cpu_addr, cpu_data_out,
1089 128 davidgb 
                         pb_cs, pb_wreg, pb_rreg )
1090 
begin
1091 
  pb_wru <= pb_cs and (not cpu_rw) and (not cpu_addr(0));
1092 
  pb_wrl <= pb_cs and (not cpu_rw) and      cpu_addr(0) ;
1093 
  pb_rdu <= pb_cs and      cpu_rw  and (not cpu_addr(0));
1094 
  pb_rdl <= pb_cs and      cpu_rw  and      cpu_addr(0) ;
1095 
  pb_a   <= cpu_addr(5 downto 1);
1096 
 
1097 
  --
1098 
  -- Register upper byte from CPU on first CPU write
1099 
  -- and lower byte from the peripheral bus on first CPU read
1100 
  --
1101 
  if cpu_reset = '1' then
1102 
    pb_wreg <= (others => '0');
1103 
    pb_rreg <= (others => '0');
1104 
  elsif clk_i'event and clk_i ='1' then
1105 
    if pb_wru = '1' then
1106 137 davidgb 
      pb_wreg <= cpu_data_out;
1107 128 davidgb 
    end if;
1108 
    if pb_rdu = '1' then
1109 137 davidgb 
      pb_rreg <= pb_d(7 downto 0);
1110 128 davidgb 
    end if;
1111 
   end if;
1112 
  --
1113 
  -- Peripheral bus read and write strobes are
1114 
  -- Syncronized with the 50 MHz clock
1115 
  -- and are asserted until the peripheral bus hold is released
1116 
  --
1117 
  if cpu_reset = '1' then
1118 
    pb_wr_n <= '1';
1119 
    pb_rd_n <= '1';
1120 
  elsif clk_i'event and clk_i ='1' then
1121 137 davidgb 
    if pb_hold = '1' then
1122 
      pb_wr_n  <= not pb_wrl;
1123 
      pb_rd_n  <= not pb_rdu;
1124 128 davidgb 
    else
1125 
      pb_wr_n <= '1';
1126 
      pb_rd_n <= '1';
1127 
    end if;
1128 
  end if;
1129 
  --
1130 
  -- The peripheral bus will be an output
1131 
  -- the registered even byte on data(15 downto 8)
1132 
  -- and the CPU odd bytes on data(7 downto 0)
1133 
  -- on odd byte writes
1134 
  --
1135 
  if pb_wrl = '1' then
1136 
    pb_d <= pb_wreg & cpu_data_out;
1137 
  else
1138 
    pb_d <= (others => 'Z');
1139 
  end if;
1140 
 
1141 
  --
1142 
  -- On even byte reads,
1143 
  -- the CPU reads the low (even) byte of the peripheral bus
1144 
  -- On odd byte reads,
1145 
  -- the CPU reads the registered (odd byte) input from the peripheral bus
1146 
  --
1147 
  if pb_rdu = '1' then
1148 
    pb_data_out <= pb_d(15 downto 8);
1149 
  elsif pb_rdl = '1' then
1150 
    pb_data_out <= pb_rreg;
1151 
  else
1152 
    pb_data_out <= (others => '0');
1153 
  end if;
1154 
 
1155 
end process;
1156 
 
1157 
--
1158 
-- Hold Peripheral bus accesses for a few cycles
1159 
--
1160 
peripheral_bus_hold: process( cpu_clk, cpu_reset, pb_rdu, pb_wrl ) --, ether_rdy )
1161 
begin
1162 
    if cpu_reset = '1' then
1163 137 davidgb 
       pb_release    <= '0';
1164 
       pb_count      <= "0000";
1165 
       pb_hold_state <= hold_release_state;
1166 
    elsif rising_edge(cpu_clk) then
1167 128 davidgb 
  --
1168 
  -- The perpheral bus hold signal should be generated on
1169 
  -- 16 bit bus read which will be on even byte reads or
1170 
  -- 16 bit bus write which will be on odd byte writes.
1171 
  --
1172 137 davidgb 
       case pb_hold_state is
1173 
       when hold_release_state =>
1174 128 davidgb 
          pb_release <= '0';
1175 137 davidgb 
          if (pb_rdu = '1') or (pb_wrl = '1') then
1176 
             pb_count      <= "0100";
1177 
             pb_hold_state <= hold_request_state;
1178 128 davidgb 
          elsif (pb_rdl = '1') or (pb_wru = '1') then
1179 
             pb_release    <= '1';
1180 137 davidgb 
             pb_hold_state <= hold_release_state;
1181 
          end if;
1182 128 davidgb 
 
1183 137 davidgb 
       when hold_request_state =>
1184 
          if pb_count = "0000" then
1185 128 davidgb 
--            if ether_rdy = '1' then
1186 
              pb_release    <= '1';
1187 137 davidgb 
              pb_hold_state <= hold_release_state;
1188 128 davidgb 
--            end if;
1189 
          else
1190 137 davidgb 
             pb_count <= pb_count - "0001";
1191 
          end if;
1192 128 davidgb 
       when others =>
1193 137 davidgb 
          null;
1194 128 davidgb 
       end case;
1195 137 davidgb 
    end if;
1196 128 davidgb 
end process;
1197 
 
1198 
--
1199 
-- Compact Flash Control
1200 
--
1201 
compact_flash: process( ide_cs, cpu_addr )
1202 
begin
1203 137 davidgb 
    ide_cs0_n  <= not( ide_cs ) or cpu_addr(4);
1204 
    ide_cs1_n  <= not( ide_cs and cpu_addr(4));
1205 
    ide_dmack_n  <= '1';
1206 128 davidgb 
end process;
1207 
 
1208 
--
1209 
-- Interrupts and other bus control signals
1210 
--
1211 
interrupts : process( SW3_N,
1212 137 davidgb 
                      pb_cs, pb_hold, pb_release, ram_hold,
1213 
--                    ether_irq,
1214 128 davidgb 
                      acia_irq,
1215 137 davidgb 
                      keyboard_irq,
1216 
                      trap_irq,
1217 
                      timer_irq
1218 
                      )
1219 128 davidgb 
begin
1220 
    pb_hold    <= pb_cs and (not pb_release);
1221 
    cpu_irq    <= acia_irq or keyboard_irq;
1222 137 davidgb 
    cpu_nmi    <= trap_irq or not( SW3_N );
1223 
    cpu_firq   <= timer_irq;
1224 
    cpu_halt   <= '0';
1225 
    cpu_hold   <= pb_hold or ram_hold;
1226 128 davidgb 
    FLASH_CE_N <= '1';
1227 
end process;
1228 
 
1229 
 
1230 
--
1231 
-- Flash 7 segment LEDS
1232 
--
1233 
my_led_flasher: process( clk_i, rst_i, CountL )
1234 
begin
1235 
    if rst_i = '1' then
1236 137 davidgb 
         CountL <= "000000000000000000000000";
1237 128 davidgb 
    elsif rising_edge(clk_i) then
1238 137 davidgb 
         CountL <= CountL + 1;
1239 128 davidgb 
    end if;
1240 137 davidgb 
--  S(7 downto 0) <= CountL(23 downto 16);
1241 128 davidgb 
end process;
1242 
 
1243 
--
1244 
-- Generate CPU & Pixel Clock from Memory Clock
1245 
--
1246 
my_prescaler : process( clk_i, clk_count )
1247 
begin
1248 
  if rising_edge( clk_i ) then
1249 
 
1250 140 davidgb 
    if clk_count = 0 then
1251 
      clk_count <= CPU_CLK_DIV-1;
1252 
    else
1253 
      clk_count <= clk_count - 1;
1254 128 davidgb 
    end if;
1255 140 davidgb 
 
1256 
    if clk_count = 0 then
1257 
       clk25 <= '0';
1258 
    elsif clk_count = (CPU_CLK_DIV/2) then
1259 
       clk25 <= '1';
1260 
    end if;
1261 
 
1262 
  end if;
1263 128 davidgb 
end process;
1264 
 
1265 
--
1266 
-- Reset button and reset timer
1267 
--
1268 
my_switch_assignments : process( rst_i, SW2_N, lock )
1269 
begin
1270 140 davidgb 
  rst_i <= not SW2_N;
1271 
  cpu_reset <= rst_i or (not lock);
1272 128 davidgb 
end process;
1273 
 
1274 
--
1275 
-- RS232 signals:
1276 
--
1277 
my_acia_assignments : process( RS232_RXD, RS232_CTS, txd, rts_n )
1278 
begin
1279 
  rxd       <= RS232_RXD;
1280 
  cts_n     <= RS232_CTS;
1281 
  dcd_n     <= '0';
1282 
  RS232_TXD <= txd;
1283 
  RS232_RTS <= rts_n;
1284 
end process;
1285 
 
1286 
--
1287 
-- Pin assignments for ethernet controller
1288 
--
1289 
my_ethernet_assignments : process( clk_i, cpu_reset, ether_cs )
1290 
begin
1291 
    ether_cs_n  <= not ether_cs;
1292 
    ether_aen   <= not ether_cs; -- Ethernet address enable not
1293 
    ether_bhe_n <= '1';          -- Ethernet bus high enable - 8 bit access only
1294 
end process;
1295 
 
1296 
--
1297 
-- I/O expansion slot assignments
1298 
--
1299 
my_slot_assignments : process( slot1_cs, slot2_cs)
1300 
begin
1301 
    slot1_cs_n <= not slot1_cs;
1302 
    slot2_cs_n <= not slot2_cs;
1303 
end process;
1304 
 
1305 
--
1306 
-- VGA ouputs
1307 
--
1308 
my_vga_assignments : process( vga_red_o, vga_green_o, vga_blue_o )
1309 
begin
1310 
  VGA_red(0)   <= vga_red_o;
1311 
  VGA_red(1)   <= vga_red_o;
1312 
  VGA_red(2)   <= vga_red_o;
1313 
  VGA_green(0) <= vga_green_o;
1314 
  VGA_green(1) <= vga_green_o;
1315 
  VGA_green(2) <= vga_green_o;
1316 
  VGA_blue(0)  <= vga_blue_o;
1317 
  VGA_blue(1)  <= vga_blue_o;
1318 
  VGA_blue(2)  <= vga_blue_o;
1319 
end process;
1320 140 davidgb 
 
1321 128 davidgb 
--
1322 
-- SDRAM read write control
1323 
--
1324 
my_sdram_rw : process( clk_i, cpu_reset,
1325 
                       opBegun, ramDone,
1326 137 davidgb 
                       ram_state,
1327 128 davidgb 
                       ram_rd_req, ram_wr_req )
1328 
begin
1329 
  if( cpu_reset = '1' ) then
1330 140 davidgb 
    hRd        <= '0';
1331 128 davidgb 
    hWr        <= '0';
1332 137 davidgb 
    ram_hold   <= '0';
1333 
    ram_state  <= ram_state_0;
1334 128 davidgb 
 
1335 
  elsif( falling_edge(clk_i) ) then
1336 
    --
1337 137 davidgb 
    -- ram state machine
1338 
    --
1339 128 davidgb 
    case ram_state is
1340 
 
1341 
    when ram_state_0 =>
1342 137 davidgb 
      if ram_rd_req = '1' then
1343 140 davidgb 
        ram_hold   <= '1';
1344 137 davidgb 
        hRd        <= '1';
1345 140 davidgb 
        ram_state  <= ram_state_rd1;
1346 
      elsif ram_wr_req = '1' then
1347 
        ram_hold   <= '1';
1348 
        hWr        <= '1';
1349 
        ram_state  <= ram_state_wr1;
1350 128 davidgb 
      end if;
1351 
 
1352 
    when ram_state_rd1 =>
1353 137 davidgb 
      if opBegun = '1' then
1354 
        hRd        <= '0';
1355 
        ram_state  <= ram_state_rd2;
1356 128 davidgb 
      end if;
1357 
 
1358 
    when ram_state_rd2 =>
1359 137 davidgb 
      if ramDone = '1' then
1360 140 davidgb 
        ram_hold   <= '0';
1361 137 davidgb 
        ram_state  <= ram_state_3;
1362 
      end if;
1363 128 davidgb 
 
1364 
    when ram_state_wr1 =>
1365 137 davidgb 
      if opBegun = '1' then
1366 140 davidgb 
        ram_hold   <= '0';
1367 137 davidgb 
        hWr        <= '0';
1368 
        ram_state  <= ram_state_3;
1369 128 davidgb 
      end if;
1370 
 
1371 
    when ram_state_3 =>
1372 137 davidgb 
      if ram_release = '1' then
1373 
        ram_state  <= ram_state_0;
1374 128 davidgb 
      end if;
1375 
 
1376 137 davidgb 
    when others =>
1377 
      hRd        <= '0';
1378 
      hWr        <= '0';
1379 140 davidgb 
      ram_hold   <= '0';
1380 137 davidgb 
      ram_state  <= ram_state_0;
1381 
    end case;
1382 128 davidgb 
 
1383 
  end if;
1384 
end process;
1385 140 davidgb 
 
1386 128 davidgb 
--
1387 140 davidgb 
-- SDRAM Address and data bus assignments
1388 
--
1389 128 davidgb 
my_sdram_addr_data : process( cpu_addr, dat_addr,
1390 
                                cpu_data_out, hDout )
1391 140 davidgb 
begin
1392 
  hAddr(23 downto 19)  <= "00000";
1393 
  hAddr(18 downto 11)  <= dat_addr;
1394 
  hAddr(10 downto 0)   <= cpu_addr(11 downto 1);
1395 
  hUds                 <= not cpu_addr(0);
1396 
  hLds                 <=     cpu_addr(0);
1397 
  if cpu_addr(0) = '0' then
1398 
     hDin( 7 downto 0) <= (others=>'0');
1399 
     hDin(15 downto 8) <= cpu_data_out;
1400 
     ram_data_out      <= hDout(15 downto 8);
1401 
  else
1402 
     hDin( 7 downto 0) <= cpu_data_out;
1403 
     hDin(15 downto 8) <= (others=>'0');
1404 
     ram_data_out      <= hDout( 7 downto 0);
1405 
  end if;
1406 128 davidgb 
end process;
1407 140 davidgb 
 
1408 128 davidgb 
--
1409 
-- Hold RAM until falling CPU clock edge
1410 
--
1411 
ram_bus_hold: process( cpu_clk, cpu_reset, ram_hold )
1412 
begin
1413 
    if ram_hold = '1' then
1414 137 davidgb 
       ram_release   <= '0';
1415 
    elsif falling_edge(cpu_clk) then
1416 
       ram_release   <= '1';
1417 
    end if;
1418 128 davidgb 
end process;
1419 140 davidgb 
 
1420 128 davidgb 
--
1421 
-- CPU read data request on rising CPU clock edge
1422 
--
1423 
ram_read_request: process( hRd, cpu_clk, ram_cs, cpu_rw, ram_release )
1424 
begin
1425 140 davidgb 
    if hRd = '1' then
1426 137 davidgb 
      ram_rd_req   <= '0';
1427 140 davidgb 
    elsif rising_edge(cpu_clk) then
1428 137 davidgb 
      if (ram_cs = '1') and (cpu_rw = '1') and (ram_release = '1') then
1429 140 davidgb 
        ram_rd_req   <= '1';
1430 
      end if;
1431 137 davidgb 
    end if;
1432 128 davidgb 
end process;
1433 140 davidgb 
 
1434 128 davidgb 
--
1435 
-- CPU write data to RAM valid on rising CPU clock edge
1436 
--
1437 
ram_write_request: process( hWr, cpu_clk, ram_cs, cpu_rw, ram_release )
1438 
begin
1439 
    if hWr = '1' then
1440 137 davidgb 
       ram_wr_req   <= '0';
1441 140 davidgb 
    elsif rising_edge(cpu_clk) then
1442 137 davidgb 
      if (ram_cs = '1') and (cpu_rw = '0') and (ram_release = '1') then
1443 140 davidgb 
        ram_wr_req   <= '1';
1444 128 davidgb 
      end if;
1445 137 davidgb 
    end if;
1446 128 davidgb 
end process;
1447 
 
1448 
 
1449 
 
1450 140 davidgb 
status_leds : process( rst_i, cpu_reset, lock )
1451 
begin
1452 
    S(0) <= rst_i;
1453 
    S(1) <= cpu_reset;
1454 
    S(2) <= lock;
1455 
    S(3) <= countL(23);
1456 
    S(7 downto 4) <= "0000";
1457 
end process;
1458 
 
1459 
--debug_proc : process( cpu_reset, cpu_clk, cpu_rw, cpu_vma,
1460 
--                      cpu_halt, cpu_hold,
1461 
--                      cpu_firq, cpu_irq, cpu_nmi,
1462 
--                      cpu_addr, cpu_data_out, cpu_data_in )
1463 
--begin
1464 
--  cpu_reset_o    <= cpu_reset;
1465 
--  cpu_clk_o      <= cpu_clk;
1466 
--  cpu_rw_o       <= cpu_rw;
1467 
--  cpu_vma_o      <= cpu_vma;
1468 
--  cpu_halt_o     <= cpu_halt;
1469 
--  cpu_hold_o     <= cpu_hold;
1470 
--  cpu_firq_o     <= cpu_firq;
1471 
--  cpu_irq_o      <= cpu_irq;
1472 
--  cpu_nmi_o      <= cpu_nmi;
1473 
--  cpu_addr_o     <= cpu_addr;
1474 
--  cpu_data_out_o <= cpu_data_out;
1475 
--  cpu_data_in_o  <= cpu_data_in;
1476 
--end process;
1477 
 
1478 
 
1479 128 davidgb 
end rtl; --===================== End of architecture =======================--
1480 
 

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