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/de2_115/pdp8_top.vhd
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--!
--! 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;

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