Subversion Repositories pdp8

--!

--! DE2-115 PDP-8 Processor

--!

--! \brief

--!      PDP-8 implementation for the DE2-115 board

--!

--! \details

--!     Switch 17 - Single step

--!     Switch 16 - Halt

--!     Switches 11 to 0 - Front panel data switches

--!     Key 2 - Address load

--!     Key 1 - Continue

--!     Key 0 - Front panel rotator switch (press to "rotate")

--!     Hex 3 to 0 - Data register

--!     Red LEDs 14 to 0 - Address register

--!

--! \file

--!      minimal_pdp8.vhd

--!

--! \author

--!    Joe Manojlovich - joe.manojlovich (at) gmail (dot) com

--!

--------------------------------------------------------------------

--

--  Copyright (C) 2012 Joe Manojlovich

--

-- This source file may be used and distributed without

-- restriction provided that this copyright statement is not

-- removed from the file and that any derivative work contains

-- the original copyright notice and the associated disclaimer.

--

-- This source file is free software; you can redistribute it

-- and/or modify it under the terms of the GNU Lesser General

-- Public License as published by the Free Software Foundation;

-- version 2.1 of the License.

--

-- This source is distributed in the hope that it will be

-- useful, but WITHOUT ANY WARRANTY; without even the implied

-- warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR

-- PURPOSE. See the GNU Lesser General Public License for more

-- details.

--

-- You should have received a copy of the GNU Lesser General

-- Public License along with this source; if not, download it

-- from http://www.gnu.org/licenses/lgpl.txt

--

--------------------------------------------------------------------

--

-- Comments are formatted for doxygen

--

LIBRARY ieee;

USE ieee.std_logic_1164.all;

USE ieee.std_logic_arith.all;

USE ieee.std_logic_unsigned.all;

use ieee.numeric_std;

use work.uart_types.all;                        --! UART Types

use work.dk8e_types.all;                        --! DK8E Types

use work.kc8e_types.all;                        --! KC8E Types

use work.kl8e_types.all;                        --! KL8E Types

use work.rk8e_types.all;                        --! RK8E Types

use work.rk05_types.all;                        --! RK05 Types

use work.ls8e_types.all;                        --! LS8E Types

use work.pr8e_types.all;                        --! PR8E Types

use work.cpu_types.all;                         --! CPU Types

use work.sd_types.all;                          --! SD Types

use work.sdspi_types.all;                       --! SPI Types

ENTITY pdp8_top IS

  generic(

    invert_reset : std_logic := '0' -- 0 : not invert, 1 invert

    );

  PORT (

    SW : IN STD_LOGIC_VECTOR(17 DOWNTO 0) := (others => 'Z');    --! Toggle switches

    KEY : IN STD_LOGIC_VECTOR(3 DOWNTO 0) := (others => 'Z');    --! Push buttons

    CLOCK_50 : IN STD_LOGIC;                                     --! Input clock

    LEDG : OUT STD_LOGIC_VECTOR(7 DOWNTO 0) := (others => 'Z');  --! Output green LEDs

    LEDR : OUT STD_LOGIC_VECTOR(17 DOWNTO 0) := (others => 'Z'); --! Output red LEDs

    SD_CLK : OUT STD_LOGIC;                                      --! SD card clock

    SD_CMD : OUT STD_LOGIC;                                      --! SD card master out slave in

    SD_DAT0 : IN STD_LOGIC;                                      --! SD card master in slave out

    SD_DAT3 : OUT STD_LOGIC;                                     --! SD card chip select

    UART_RXD : IN STD_LOGIC;                                     --! UART receive line

    UART_TXD : OUT STD_LOGIC;                                    --! UART send line

    HEX0 : OUT STD_LOGIC_VECTOR(6 DOWNTO 0) := (others => 'Z');  --! 7 segment display 0

    HEX1 : OUT STD_LOGIC_VECTOR(6 DOWNTO 0) := (others => 'Z');  --! 7 segment display 1

    HEX2 : OUT STD_LOGIC_VECTOR(6 DOWNTO 0) := (others => 'Z');  --! 7 segment display 2

    HEX3 : OUT STD_LOGIC_VECTOR(6 DOWNTO 0) := (others => 'Z')   --! 7 segment display 3

    );

END pdp8_top;

architecture rtl of pdp8_top is

  signal rk8eSTAT : rk8eSTAT_t;

  signal ledDATA : std_logic_vector(11 downto 0) := (others => 'Z'); --! Output data register

  signal swCNTL : swCNTL_t := (others => '0');                       --! Front Panel Control Switches

  signal swROT : swROT_t := dispPC;                                  --! Front panel rotator switch

  signal swOPT  : swOPT_t;                                           --! PDP-8 options

  signal dly: std_logic := '0';         --! Delay used for reset logic

  signal rst: std_logic := '0';         --! Internal reset line

  signal int_reset : std_logic;         --! Initial reset line

  signal rst_out : std_logic;           --! Reset line output to PDP-8

begin

  swOPT.KE8       <= '1';

  swOPT.KM8E      <= '1';

  swOPT.TSD       <= '1';

  swOPT.STARTUP   <= '1'; -- Setting the 'STARTUP' bit will cause the PDP8 to boot

  -- to the address in the switch register

  int_reset <= '0';

  ----------------------------------------------------------------------------

  --  RESET signal generator.

  ----------------------------------------------------------------------------

  process(CLOCK_50)

  begin

    if(rising_edge(CLOCK_50)) then

      dly <= ( not(int_reset) and     dly  and not(rst) )

             or ( not(int_reset) and not(dly) and     rst  );

      rst <= ( not(int_reset) and not(dly) and not(rst) );

    end if;

  end process;

  rst_out <= rst xor invert_reset ;

  ----------------------------------------------------------------------------

  -- Display toggle switch (stand in for rotator switch)

  ---------------------------------------------------------------------------  

  toggle_switch : process(CLOCK_50)

  begin

    if rising_edge(KEY(0)) then

      swROT <= swROT + 1;

    end if;

  end process toggle_switch;

  ----------------------------------------------------------------------------

  -- Process that converts address into hex for the 7 segment displays

  ---------------------------------------------------------------------------  

  displaystate : process (CLOCK_50)

  begin

    if rising_edge(CLOCK_50) then

      case ledDATA(11 downto 9) is

        when O"0" => HEX3 <= "1000000";

        when O"1" => HEX3 <= "1111001";

        when O"2" => HEX3 <= "0100100";

        when O"3" => HEX3 <= "0110000";

        when O"4" => HEX3 <= "0011001";

        when O"5" => HEX3 <= "0010010";

        when O"6" => HEX3 <= "0000010";

        when O"7" => HEX3 <= "1111000";

        when others => null;

      end case;

      case ledDATA(8 downto 6) is

        when O"0" => HEX2 <= "1000000";

        when O"1" => HEX2 <= "1111001";

        when O"2" => HEX2 <= "0100100";

        when O"3" => HEX2 <= "0110000";

        when O"4" => HEX2 <= "0011001";

        when O"5" => HEX2 <= "0010010";

        when O"6" => HEX2 <= "0000010";

        when O"7" => HEX2 <= "1111000";

        when others => null;

      end case;

      case ledDATA(5 downto 3) is

        when O"0" => HEX1 <= "1000000";

        when O"1" => HEX1 <= "1111001";

        when O"2" => HEX1 <= "0100100";

        when O"3" => HEX1 <= "0110000";

        when O"4" => HEX1 <= "0011001";

        when O"5" => HEX1 <= "0010010";

        when O"6" => HEX1 <= "0000010";

        when O"7" => HEX1 <= "1111000";

        when others => null;

      end case;

      case ledDATA(2 downto 0) is

        when O"0" => HEX0 <= "1000000";

        when O"1" => HEX0 <= "1111001";

        when O"2" => HEX0 <= "0100100";

        when O"3" => HEX0 <= "0110000";

        when O"4" => HEX0 <= "0011001";

        when O"5" => HEX0 <= "0010010";

        when O"6" => HEX0 <= "0000010";

        when O"7" => HEX0 <= "1111000";

        when others => null;

      end case;

    end if;

  end process displaystate;

  swCNTL.step <= SW(17);                -- Single step switch

  swCNTL.halt <= SW(16);                -- Halt switch

  swCNTL.loadADDR <= KEY(2);            -- Address load momentary switch

  swCNTL.cont <= KEY(1);                -- Continue momentary switch

  ----------------------------------------------------------------------------

  -- PDP8 Processor

  ---------------------------------------------------------------------------    

  iPDP8 : entity work.ePDP8 (rtl) port map (

    -- System

    clk      => CLOCK_50,                   --! 50 MHz Clock

    rst      => rst_out,                    --! Reset Button

    -- CPU Configuration

    swCPU    => swPDP8A,                    --! CPU Configured to emulate PDP8A

    swOPT    => swOPT,                      --! Enable Options

    -- Real Time Clock Configuration

    swRTC    => clkDK8EC2,                  --! RTC 50 Hz interrupt

    -- TTY1 Interfaces

    tty1BR   => uartBR9600,                 --! TTY1 is 9600 Baud

    tty1HS   => uartHSnone,                 --! TTY1 has no flow control

    tty1CTS  => '1',                        --! TTY1 doesn't need CTS

    tty1RTS  => open,                       --! TTY1 doesn't need RTS

    tty1RXD  => UART_RXD,                   --! TTY1 RXD (to RS-232 interface)

    tty1TXD  => UART_TXD,                   --! TTY1 TXD (to RS-232 interface)

    -- TTY2 Interfaces

    tty2BR   => uartBR9600,                 --! TTY2 is 9600 Baud

    tty2HS   => uartHSnone,                 --! TTY2 has no flow control

    tty2CTS  => '1',                        --! TTY2 doesn't need CTS

    tty2RTS  => open,                       --! TTY2 doesn't need RTS

    tty2RXD  => '1',                        --! TTY2 RXD (tied off)

    tty2TXD  => open,                       --! TTY2 TXD (tied off)

    -- LPR Interface

    lprBR    => uartBR9600,                 --! LPR is 9600 Baud

    lprHS    => uartHSnone,                 --! LPR has no flow control

    lprDTR   => '1',                        --! LPR doesn't need DTR

    lprDSR   => open,                       --! LPR doesn't need DSR

    lprRXD   => '1',                        --! LPR RXD (tied off)

    lprTXD   => open,                       --! LPR TXD (tied off)

    -- Paper Tape Reader Interface

    ptrBR    => uartBR9600,                 --! PTR is 9600 Baud

    ptrHS    => uartHSnone,                 --! PTR has no flow control

    ptrCTS   => '1',                        --! PTR doesn't need CTS

    ptrRTS   => open,                       --! PTR doesn't need RTS

    ptrRXD   => '1',                        --! PTR RXD (tied off)

    ptrTXD   => open,                       --! PTR TXD (tied off)

    -- Secure Digital Disk Interface

    sdCD     => '0',                        --! SD Card Detect

    sdWP     => '0',                        --! SD Write Protect

    sdMISO   => SD_DAT0,                    --! SD Data In

    sdMOSI   => SD_CMD,                     --! SD Data Out

    sdSCLK   => SD_CLK,                     --! SD Clock

    sdCS     => SD_DAT3,                    --! SD Chip Select

    -- Status

    rk8eSTAT => rk8eSTAT,                   --! Disk Status (Ignore)

    -- Switches and LEDS

    swROT    => swROT,                      --! Data LEDS display PC

    swDATA   => SW(11 DOWNTO 0),            --! RK8E Boot Loader Address

    swCNTL   => swCNTL,                     --! Switches

    ledRUN => LEDR(17),                     --! Run LED

    ledDATA => ledDATA,                     --! Data output register

    ledADDR => LEDR(14 downto 0)            --! Address output register

    );

end rtl;