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SharpMZ_MiSTer/common/mctrl.vhd
root 0acc4dfbf0 Initial commit
2018-09-28 17:04:36 +01:00

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---------------------------------------------------------------------------------------------------------
--
-- Name: mctrl.vhd
-- Created: July 2018
-- Author(s): Philip Smart
-- Description: Sharp MZ series Programmable Machine Control logic.
-- This module forms the Programmable control of the emulation along with sync reset
-- management.
-- A set of 16 addressable registers is presented on the external IOCTL interface.
-- Each register controls an aspect of the emulation, such as video mode or cpu speed.
--
-- Reset to all components is managed by this module, taking cold, warm and internally
-- generated reset signals and creating a unified system reset output.
--
-- Please see the docs/SharpMZ_Notes.xlsx spreadsheet for details on these registers
-- and the values they take.
--
-- Credits:
-- Copyright: (c) 2018 Philip Smart <philip.smart@net2net.org>
--
-- History: July 2018 - Initial module written.
--
---------------------------------------------------------------------------------------------------------
-- This source file is free software: you can redistribute it and-or modify
-- it under the terms of the GNU General Public License as published
-- by the Free Software Foundation, either version 3 of the License, or
-- (at your option) any later version.
--
-- This source file 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 General Public License for more details.
--
-- You should have received a copy of the GNU General Public License
-- along with this program. If not, see <http:--www.gnu.org-licenses->.
---------------------------------------------------------------------------------------------------------
package mctrl_pkg is
-- Config Bus
--
subtype CONFIG_WIDTH is integer range 58 downto 0;
-- Mode signals indicating type of machine we are emulating.
--
constant MZ80K : integer := 0; -- Machine is an MZ80K
constant MZ80C : integer := 1; -- Machine is an MZ80C
constant MZ1200 : integer := 2; -- Machine is an MZ1200
constant MZ80A : integer := 3; -- Machine is an MZ80A
constant MZ700 : integer := 4; -- Machine is an MZ700
constant MZ800 : integer := 5; -- Machine is an MZ800
constant MZ80B : integer := 6; -- Machine is an MZ80B
constant MZ2000 : integer := 7; -- Machine is an MZ2000
subtype CURRENTMACHINE is integer range 7 downto 0; -- Range of bits to indicate current machine, only 1 bit is set at a time.
constant MZ_KC : integer := 8; -- Machine is an MZ80K/MZ80C
constant MZ_A : integer := 9; -- Machine is an MZ1200/MZ80A
constant MZ_B : integer := 10; -- Machine is an MZ2000/MZ80B
constant MZ_80B : integer := 11; -- Machine is an MZ2000/MZ80B
constant MZ_80C : integer := 12; -- Machine is an MZ80K/MZ80C/MZ1200/MZ80A
-- Type of display to emulate.
--
constant NORMAL : integer := 13; -- Normal 40 x 25 character monochrome display.
constant NORMAL80 : integer := 14; -- Normal 80 x 25 character monochrome display.
constant COLOUR : integer := 15; -- Colour 40 x 25 character display.
constant COLOUR80 : integer := 16; -- Colour 80 x 25 character display.
-- Option Roms Enable (some machines by design dont have them, but this emulation allows them to be enabled if needed).
--
subtype USERROM is integer range 24 downto 17; -- User ROM E800 - EFFF enable per machine.
subtype FDCROM is integer range 32 downto 25; -- FDC ROM F000 - FFFF enable per machine.
-- Various configurable settings.
--
constant AUDIOSRC : integer := 33; -- Audio source, 0 = sound generator, 1 = tape audio.
subtype TURBO is integer range 36 downto 34; -- 2MHz/4MHz/8MHz/16MHz/32MHz switch (various).
subtype FASTTAPE is integer range 39 downto 37; -- Speed of tape read/write.
subtype BUTTONS is integer range 41 downto 40; -- Various external buttons, such as CMT play/record.
constant PCGRAM : integer := 42; -- PCG ROM(0) or RAM(1) based.
constant VRAMWAIT : integer := 43; -- Insert video wait states on CPU access as per original design.
constant VRAMDISABLE : integer := 44; -- Disable the Video RAM from display output.
constant GRAMDISABLE : integer := 45; -- Disable the graphics RAM from display output.
-- Derivative settings to program the clock generator.
--
subtype CPUSPEED is integer range 49 downto 46; -- Active CPU Speed.
subtype VIDSPEED is integer range 52 downto 50; -- Active Video Speed.
subtype PERSPEED is integer range 54 downto 53; -- Active Peripheral Speed.
subtype RTCSPEED is integer range 56 downto 55; -- Active RTC Speed.
subtype SNDSPEED is integer range 58 downto 57; -- Active Sound Speed.
-- CMT Bus
--
subtype CMTBUS_WIDTH is integer range 8 downto 0;
-- CMT Signals.
--
constant PLAY_READY : integer := 0; -- Tape play back buffer, 0 = empty, 1 = full.
constant PLAYING : integer := 1; -- Tape playback, 0 = stopped, 1 = in progress.
constant RECORD_READY : integer := 2; -- Tape record buffer full.
constant RECORDING : integer := 3; -- Tape recording, 0 = stopped, 1 = in progress.
constant ACTIVE : integer := 4; -- Tape transfer in progress, 0 = no activity, 1 = activity.
constant SENSE : integer := 5; -- Tape state Sense out.
constant WRITEBIT : integer := 6; -- Write bit to MZ.
constant READBIT : integer := 7; -- Receive bit from MZ.
constant MOTOR : integer := 8; -- Motor on/off.
-- Debug Bus
--
subtype DEBUG_WIDTH is integer range 15 downto 0;
-- Debugging signals.
--
subtype LEDS_BANK is integer range 2 downto 0;
subtype LEDS_SUBBANK is integer range 5 downto 3;
constant LEDS_ON : integer := 6;
constant ENABLED : integer := 7;
subtype SMPFREQ is integer range 11 downto 8;
subtype CPUFREQ is integer range 15 downto 12;
end mctrl_pkg;
library IEEE;
library pkgs;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;
use pkgs.mctrl_pkg.all;
use pkgs.clkgen_pkg.all;
entity mctrl is
Port (
-- Clock signals used by this module.
CLKBUS : in std_logic_vector(CLKBUS_WIDTH);
-- Reset's
COLD_RESET : in std_logic;
WARM_RESET : in std_logic;
SYSTEM_RESET : out std_logic;
-- HPS Interface
IOCTL_CLK : in std_logic; -- HPS I/O Clock.
IOCTL_WR : in std_logic; -- HPS Write Enable to FPGA.
IOCTL_RD : in std_logic; -- HPS Read Enable from FPGA.
IOCTL_ADDR : in std_logic_vector(24 downto 0); -- HPS Address in FPGA to write into.
IOCTL_DOUT : in std_logic_vector(15 downto 0); -- HPS Data to be written into FPGA.
IOCTL_DIN : out std_logic_vector(15 downto 0); -- HPS Data to be read into HPS.
-- Different operations modes.
CONFIG : out std_logic_vector(CONFIG_WIDTH);
-- Cassette magnetic tape signals.
CMTBUS : in std_logic_vector(CMTBUS_WIDTH);
-- Debug modes.
DEBUG : out std_logic_vector(DEBUG_WIDTH)
);
end mctrl;
architecture rtl of mctrl is
signal REGISTER_MODEL : std_logic_vector(7 downto 0) := "00000011";
signal REGISTER_DISPLAY : std_logic_vector(7 downto 0) := "00000000";
signal REGISTER_CPU : std_logic_vector(7 downto 0) := "00000000";
signal REGISTER_AUDIO : std_logic_vector(7 downto 0) := "00000000";
signal REGISTER_CMT : std_logic_vector(7 downto 0) := "00000000";
signal REGISTER_CMT2 : std_logic_vector(7 downto 0) := "00000000";
signal REGISTER_USERROM : std_logic_vector(7 downto 0) := "00000000";
signal REGISTER_FDCROM : std_logic_vector(7 downto 0) := "00000000";
signal REGISTER_8 : std_logic_vector(7 downto 0) := "00000000";
signal REGISTER_9 : std_logic_vector(7 downto 0) := "00000000";
signal REGISTER_10 : std_logic_vector(7 downto 0) := "00000000";
signal REGISTER_11 : std_logic_vector(7 downto 0) := "00000000";
signal REGISTER_12 : std_logic_vector(7 downto 0) := "00000000";
signal REGISTER_13 : std_logic_vector(7 downto 0) := "00000000";
signal REGISTER_DEBUG : std_logic_vector(7 downto 0) := "00001000";
signal REGISTER_DEBUG2 : std_logic_vector(7 downto 0) := "00000000";
signal delay : integer range 0 to 31;
signal REGISTER_RESET : std_logic;
begin
-- Synchronise the register update with the configuration signals according to the CPU clock.
--
process (COLD_RESET, CLKBUS(CKCPU))
begin
if COLD_RESET = '1' then
CONFIG(CONFIG_WIDTH) <= "00000000000000000000000000000000000000000000011001000001000";
elsif CLKBUS(CKCPU)'event and CLKBUS(CKCPU)='0' then
if REGISTER_MODEL(2 downto 0) = "000" then
CONFIG(MZ80K) <= '1';
else
CONFIG(MZ80K) <= '0';
end if;
if REGISTER_MODEL(2 downto 0) = "001" then
CONFIG(MZ80C) <= '1';
else
CONFIG(MZ80C) <= '0';
end if;
if REGISTER_MODEL(2 downto 0) = "010" then
CONFIG(MZ1200) <= '1';
else
CONFIG(MZ1200) <= '0';
end if;
if REGISTER_MODEL(2 downto 0) = "011" then
CONFIG(MZ80A) <= '1';
else
CONFIG(MZ80A) <= '0';
end if;
if REGISTER_MODEL(2 downto 0) = "100" then
CONFIG(MZ700) <= '1';
else
CONFIG(MZ700) <= '0';
end if;
if REGISTER_MODEL(2 downto 0) = "101" then
CONFIG(MZ800) <= '1';
else
CONFIG(MZ800) <= '0';
end if;
if REGISTER_MODEL(2 downto 0) = "110" then
CONFIG(MZ80B) <= '1';
else
CONFIG(MZ80B) <= '0';
end if;
if REGISTER_MODEL(2 downto 0) = "111" then
CONFIG(MZ2000) <= '1';
else
CONFIG(MZ2000) <= '0';
end if;
if REGISTER_MODEL(2 downto 0) = "000" or REGISTER_MODEL(2 downto 0) = "001" then
CONFIG(MZ_KC) <= '1';
else
CONFIG(MZ_KC) <= '0';
end if;
if REGISTER_MODEL(2 downto 0) = "010" or REGISTER_MODEL(2 downto 0) = "011" then
CONFIG(MZ_A) <= '1';
else
CONFIG(MZ_A) <= '0';
end if;
if REGISTER_MODEL(2 downto 0) = "110" or REGISTER_MODEL(2 downto 0) = "111" then
CONFIG(MZ_B) <= '1';
else
CONFIG(MZ_B) <= '0';
end if;
if REGISTER_MODEL(2 downto 0) /= "110" and REGISTER_MODEL(2 downto 0) /= "111" then
CONFIG(MZ_80C) <= '1';
else
CONFIG(MZ_80C) <= '0';
end if;
if REGISTER_MODEL(2 downto 0) = "110" or REGISTER_MODEL(2 downto 0) = "111" then
CONFIG(MZ_80B) <= '1';
else
CONFIG(MZ_80B) <= '0';
end if;
if REGISTER_DISPLAY(2 downto 0) = "000" then
CONFIG(NORMAL) <= '1';
else
CONFIG(NORMAL) <= '0';
end if;
if REGISTER_DISPLAY(2 downto 0) = "001" then
CONFIG(NORMAL80) <= '1';
else
CONFIG(NORMAL80) <= '0';
end if;
if REGISTER_DISPLAY(2 downto 0) = "010" then
CONFIG(COLOUR) <= '1';
else
CONFIG(COLOUR) <= '0';
end if;
if REGISTER_DISPLAY(2 downto 0) = "011" then
CONFIG(COLOUR80) <= '1';
else
CONFIG(COLOUR80) <= '0';
end if;
-- Convert CPU/CMT and Debug speed selections to actual CPU speed.
-- If debugging enabled and Debug freq not 0, select otherwise CMT if CMT is active, otherwise CPU speed as required.
--
-- Mapping could be made in software or 1-1 with the register, but setting restrictions and mapping in hw preferred, it
-- limits frequencies belonging to a given machine and makes it easier to change the frequency by NIOS or other controller if
-- MiSTer not used.
if CMTBUS(ACTIVE) = '1' then
if REGISTER_MODEL /= "100" and REGISTER_MODEL(2 downto 0) /= "110" and REGISTER_MODEL(2 downto 0) /= "111" then
case REGISTER_CMT(2 downto 0) is
when "000" => CONFIG(CPUSPEED) <= "0000"; -- 2MHz
when "001" => CONFIG(CPUSPEED) <= "0010"; -- 4MHz
when "010" => CONFIG(CPUSPEED) <= "0100"; -- 8MHz
when "011" => CONFIG(CPUSPEED) <= "0110"; -- 16MHz
when "100" => CONFIG(CPUSPEED) <= "1000"; -- 32MHz
when "101" => CONFIG(CPUSPEED) <= "1010"; -- 64MHz
when "110" => CONFIG(CPUSPEED) <= "0000"; -- 2MHz
when "111" => CONFIG(CPUSPEED) <= "0000"; -- 2MHz
end case;
elsif REGISTER_MODEL(2 downto 0) = "100" then
case REGISTER_CMT(2 downto 0) is
when "000" => CONFIG(CPUSPEED) <= "0001"; -- 3.5MHz
when "001" => CONFIG(CPUSPEED) <= "0011"; -- 7MHz
when "010" => CONFIG(CPUSPEED) <= "0101"; -- 14MHz
when "011" => CONFIG(CPUSPEED) <= "0111"; -- 28MHz
when "100" => CONFIG(CPUSPEED) <= "1001"; -- 56MHz
when "101" => CONFIG(CPUSPEED) <= "1011"; -- 112MHz
when "110" => CONFIG(CPUSPEED) <= "0001"; -- 3.5MHz
when "111" => CONFIG(CPUSPEED) <= "0001"; -- 3.5MHz
end case;
elsif REGISTER_MODEL(2 downto 0) = "110" or REGISTER_MODEL(2 downto 0) = "110" then
case REGISTER_CMT(2 downto 0) is
when "000" => CONFIG(CPUSPEED) <= "0010"; -- 4MHz
when "001" => CONFIG(CPUSPEED) <= "0100"; -- 8MHz
when "010" => CONFIG(CPUSPEED) <= "0110"; -- 16MHz
when "011" => CONFIG(CPUSPEED) <= "1000"; -- 32MHz
when "100" => CONFIG(CPUSPEED) <= "1010"; -- 64MHz
when "101" => CONFIG(CPUSPEED) <= "0010"; -- 4MHz
when "110" => CONFIG(CPUSPEED) <= "0010"; -- 4MHz
when "111" => CONFIG(CPUSPEED) <= "0010"; -- 4MHz
end case;
else
CONFIG(CPUSPEED) <= "0000"; -- Default 2MHz
end if;
else
if REGISTER_MODEL /= "100" and REGISTER_MODEL(2 downto 0) /= "110" and REGISTER_MODEL(2 downto 0) /= "111" then
case REGISTER_CPU(2 downto 0) is
when "000" => CONFIG(CPUSPEED) <= "0000"; -- 2MHz
when "001" => CONFIG(CPUSPEED) <= "0010"; -- 4MHz
when "010" => CONFIG(CPUSPEED) <= "0100"; -- 8MHz
when "011" => CONFIG(CPUSPEED) <= "0110"; -- 16MHz
when "100" => CONFIG(CPUSPEED) <= "1000"; -- 32MHz
when "101" => CONFIG(CPUSPEED) <= "1010"; -- 64MHz
when "110" => CONFIG(CPUSPEED) <= "0000"; -- 2MHz
when "111" => CONFIG(CPUSPEED) <= "0000"; -- 2MHz
end case;
elsif REGISTER_MODEL(2 downto 0) = "100" then
case REGISTER_CPU(2 downto 0) is
when "000" => CONFIG(CPUSPEED) <= "0001"; -- 3.5MHz
when "001" => CONFIG(CPUSPEED) <= "0011"; -- 7MHz
when "010" => CONFIG(CPUSPEED) <= "0101"; -- 14MHz
when "011" => CONFIG(CPUSPEED) <= "0111"; -- 28MHz
when "100" => CONFIG(CPUSPEED) <= "1001"; -- 56MHz
when "101" => CONFIG(CPUSPEED) <= "1011"; -- 112MHz
when "110" => CONFIG(CPUSPEED) <= "0001"; -- 3.5MHz
when "111" => CONFIG(CPUSPEED) <= "0001"; -- 3.5MHz
end case;
elsif REGISTER_MODEL(2 downto 0) = "110" or REGISTER_MODEL(2 downto 0) = "110" then
case REGISTER_CPU(2 downto 0) is
when "000" => CONFIG(CPUSPEED) <= "0010"; -- 4MHz
when "001" => CONFIG(CPUSPEED) <= "0100"; -- 8MHz
when "010" => CONFIG(CPUSPEED) <= "0110"; -- 16MHz
when "011" => CONFIG(CPUSPEED) <= "1000"; -- 32MHz
when "100" => CONFIG(CPUSPEED) <= "1010"; -- 64MHz
when "101" => CONFIG(CPUSPEED) <= "0010"; -- 4MHz
when "110" => CONFIG(CPUSPEED) <= "0010"; -- 4MHz
when "111" => CONFIG(CPUSPEED) <= "0010"; -- 4MHz
end case;
else
CONFIG(CPUSPEED) <= "0000"; -- Default 2MHz
end if;
end if;
-- Setup the video speed dependent upon model and graphics option.
--
-- MZ700/MZ800 Models.
if REGISTER_MODEL(2 downto 0) = "100" or REGISTER_MODEL(2 downto 0) = "101" then
-- Currently all modes default to one speed!
case REGISTER_DISPLAY(2 downto 0) is
-- 40x25 mode requires 8.8MHz clock, Mono and Colour.
when "000" | "010" | "100" | "101" | "110" | "111" =>
CONFIG(VIDSPEED) <= "010";
-- 80x25 mode requires 17.7MHz clock, Mono and Colour.
when "001" | "011" =>
CONFIG(VIDSPEED) <= "011";
end case;
-- MZ80K/C/1200/A
elsif REGISTER_MODEL(2 downto 0) /= "110" and REGISTER_MODEL(2 downto 0) /= "111" then
case REGISTER_DISPLAY(2 downto 0) is
-- 40x25 mode requires 8MHz clock, Mono and Colour.
when "000" | "010" | "100" | "101" | "110" | "111" =>
CONFIG(VIDSPEED) <= "000";
-- 80x25 mode requires 16MHz clock, Mono and Colour.
when "001" | "011" =>
CONFIG(VIDSPEED) <= "001";
end case;
-- MZ80B or MZ2200
elsif REGISTER_MODEL(2 downto 0) = "110" or REGISTER_MODEL(2 downto 0) = "111" then
case REGISTER_DISPLAY(2 downto 0) is
-- 40x25 mode requires 16MHz clock
when "000" | "001" | "010" | "011" | "100" | "101" | "110" | "111" =>
CONFIG(VIDSPEED) <= "001";
end case;
else
CONFIG(VIDSPEED) <= "000";
end if;
-- Setup RTC clock frequency dependent upon model.
if REGISTER_MODEL(2 downto 0) /= "110" and REGISTER_MODEL(2 downto 0) /= "111" then
CONFIG(RTCSPEED) <= "00";
elsif REGISTER_MODEL(2 downto 0) = "101" or REGISTER_MODEL(2 downto 0) = "110" then
CONFIG(RTCSPEED) <= "01";
elsif REGISTER_MODEL(2 downto 0) = "100" then
CONFIG(RTCSPEED) <= "10";
else
CONFIG(RTCSPEED) <= "00";
end if;
if REGISTER_MODEL(2 downto 0) /= "110" and REGISTER_MODEL(2 downto 0) /= "111" then
CONFIG(SNDSPEED) <= "00";
elsif REGISTER_MODEL(2 downto 0) = "101" or REGISTER_MODEL(2 downto 0) = "110" then
CONFIG(SNDSPEED) <= "00";
elsif REGISTER_MODEL(2 downto 0) = "100" then
CONFIG(SNDSPEED) <= "01";
else
CONFIG(SNDSPEED) <= "00";
end if;
-- Setup the peripheral speed.
if REGISTER_MODEL(2 downto 0) /= "110" and REGISTER_MODEL(2 downto 0) /= "111" then
CONFIG(PERSPEED) <= "00";
elsif REGISTER_MODEL(2 downto 0) = "101" or REGISTER_MODEL(2 downto 0) = "110" then
CONFIG(PERSPEED) <= "00";
elsif REGISTER_MODEL(2 downto 0) = "100" then
CONFIG(PERSPEED) <= "00";
else
CONFIG(PERSPEED) <= "00";
end if;
CONFIG(VRAMDISABLE)<= REGISTER_DISPLAY(4);
CONFIG(GRAMDISABLE)<= REGISTER_DISPLAY(5);
CONFIG(VRAMWAIT) <= REGISTER_DISPLAY(6);
CONFIG(PCGRAM) <= REGISTER_DISPLAY(7);
CONFIG(TURBO) <= REGISTER_CPU(2 downto 0);
CONFIG(FASTTAPE) <= REGISTER_CMT(2 downto 0);
CONFIG(BUTTONS) <= REGISTER_CMT(4 downto 3);
CONFIG(AUDIOSRC) <= REGISTER_AUDIO(0);
DEBUG(LEDS_BANK) <= REGISTER_DEBUG(2 downto 0);
DEBUG(LEDS_SUBBANK)<= REGISTER_DEBUG(5 downto 3);
DEBUG(LEDS_ON) <= REGISTER_DEBUG(6);
DEBUG(ENABLED) <= REGISTER_DEBUG(7);
DEBUG(SMPFREQ) <= REGISTER_DEBUG2(3 downto 0);
DEBUG(CPUFREQ) <= REGISTER_DEBUG2(7 downto 4);
end if;
end process;
-- Machine control is just a set of registers holding latched signals to configure machine components.
-- A write is made on address 100000000000000000000AAAA to read/write the registers, direction is via the
-- RD/WR signals.
-- AAAA specifies which register to read/write.
--
process (COLD_RESET, IOCTL_CLK)
begin
if COLD_RESET = '1' then
REGISTER_MODEL <= "00000011";
REGISTER_DISPLAY <= "00000000";
REGISTER_CPU <= "00000000";
REGISTER_AUDIO <= "00000000";
REGISTER_CMT <= "00000000";
REGISTER_CMT2 <= "00000000";
REGISTER_USERROM <= "00000000";
REGISTER_FDCROM <= "00000000";
REGISTER_8 <= "00000000";
REGISTER_9 <= "00000000";
REGISTER_10 <= "00000000";
REGISTER_11 <= "00000000";
REGISTER_12 <= "00000000";
REGISTER_13 <= "00000000";
REGISTER_DEBUG <= "00000000";
REGISTER_DEBUG2 <= "00000000";
REGISTER_RESET <= '1';
elsif IOCTL_CLK'event and IOCTL_CLK='1' then
-- For reading of registers, if no specific signal is required, just read back the output latch.
--
if IOCTL_ADDR(24) = '1' and IOCTL_RD = '1' then
case IOCTL_ADDR(3 downto 0) is
when "0000" => IOCTL_DIN <= X"00" & REGISTER_MODEL;
when "0001" => IOCTL_DIN <= X"00" & REGISTER_DISPLAY;
when "0010" => IOCTL_DIN <= X"00" & REGISTER_CPU;
when "0011" => IOCTL_DIN <= X"00" & REGISTER_AUDIO;
when "0100" => IOCTL_DIN <= X"00" & CMTBUS(7 downto 0);
when "0101" => IOCTL_DIN <= X"00" & REGISTER_CMT2(7 downto 1) & CMTBUS(8 downto 8);
when "0110" => IOCTL_DIN <= X"00" & REGISTER_USERROM;
when "0111" => IOCTL_DIN <= X"00" & REGISTER_FDCROM;
when "1000" => IOCTL_DIN <= X"00" & REGISTER_8;
when "1001" => IOCTL_DIN <= X"00" & REGISTER_9;
when "1010" => IOCTL_DIN <= X"00" & REGISTER_10;
when "1011" => IOCTL_DIN <= X"00" & REGISTER_11;
when "1100" => IOCTL_DIN <= X"00" & REGISTER_12;
when "1101" => IOCTL_DIN <= X"00" & REGISTER_13;
when "1110" => IOCTL_DIN <= X"00" & REGISTER_DEBUG;
when "1111" => IOCTL_DIN <= X"00" & REGISTER_DEBUG2;
end case;
end if;
-- For writing of registers, just assign the input bus to the register.
if IOCTL_ADDR(24) = '1' and IOCTL_WR = '1' then
case IOCTL_ADDR(3 downto 0) is
when "0000" =>
-- Assign the model data to the register and preset the default display hardware.
REGISTER_MODEL <= IOCTL_DOUT(7 downto 0);
case IOCTL_DOUT(2 downto 0) is
when "000" | "001" | "010" | "011" =>
REGISTER_DISPLAY <= REGISTER_DISPLAY(7 downto 3) & "000";
when "100" | "101" =>
REGISTER_DISPLAY <= REGISTER_DISPLAY(7 downto 3) & "010";
when "110" | "111" =>
REGISTER_DISPLAY <= REGISTER_DISPLAY(7 downto 3) & "000";
end case;
REGISTER_RESET <= '1';
when "0001" =>
REGISTER_DISPLAY <= IOCTL_DOUT(7 downto 0);
-- Reset display if the mode changes.
if REGISTER_DISPLAY(2 downto 0) /= IOCTL_DOUT(2 downto 0) then
REGISTER_RESET <= '1';
end if;
when "0010" => REGISTER_CPU <= IOCTL_DOUT(7 downto 0);
when "0011" => REGISTER_AUDIO <= IOCTL_DOUT(7 downto 0);
when "0100" => REGISTER_CMT <= IOCTL_DOUT(7 downto 0);
when "0101" => REGISTER_CMT2 <= IOCTL_DOUT(7 downto 0);
when "0110" => REGISTER_USERROM <= IOCTL_DOUT(7 downto 0);
when "0111" => REGISTER_FDCROM <= IOCTL_DOUT(7 downto 0);
when "1000" => REGISTER_8 <= IOCTL_DOUT(7 downto 0);
when "1001" => REGISTER_9 <= IOCTL_DOUT(7 downto 0);
when "1010" => REGISTER_10 <= IOCTL_DOUT(7 downto 0);
when "1011" => REGISTER_11 <= IOCTL_DOUT(7 downto 0);
when "1100" => REGISTER_12 <= IOCTL_DOUT(7 downto 0);
when "1101" => REGISTER_13 <= IOCTL_DOUT(7 downto 0);
when "1110" => REGISTER_DEBUG <= IOCTL_DOUT(7 downto 0);
when "1111" => REGISTER_DEBUG2 <= IOCTL_DOUT(7 downto 0);
end case;
end if;
-- Only allow reset signal to be active for 1 clock cycle, just enough to trigger a system reset.
--
if REGISTER_RESET = '1' then
REGISTER_RESET <= '0';
end if;
end if;
end process;
-- System reset oneshot, triggered on COLD/WARM reset or a status change.
process (CLKBUS(CKRESET), COLD_RESET, WARM_RESET, REGISTER_RESET)
begin
if COLD_RESET = '1' or WARM_RESET = '1' or REGISTER_RESET = '1' then
if COLD_RESET = '1' then
delay <= 1;
elsif WARM_RESET = '1' then
delay <= 16;
else
delay <= 16;
end if;
elsif CLKBUS(CKRESET)'event and CLKBUS(CKRESET) = '1' then
if delay /= 0 then
delay <= delay + 1;
elsif delay >= 31 then
delay <= 0;
end if;
end if;
end process;
SYSTEM_RESET <= '1' when delay > 0
else '0';
end rtl;
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