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Valerio63 |
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-- 8 bit microprocessor (65C02) with some enhances VHDL project --
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-- Full RTL synchronous pipelined architecture --
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-- Project by Valerio Venturi (Italy) --
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-- Date: 14/04/2011 --
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-- Last revision: 05/05/2011 --
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----------------------------------------------------------------------
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library IEEE;
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use IEEE.std_logic_1164.all; -- defines std_logic types
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use IEEE.STD_LOGIC_unsigned.all;
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use IEEE.STD_LOGIC_arith.all;
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-- global architecture
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entity v6502 is
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port( clk0: in STD_LOGIC; -- PHASE0 clock input
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res: in STD_LOGIC; -- reset input
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irq: in STD_LOGIC; -- interrupt request input
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nmi: in STD_LOGIC; -- not maskable interrupt input
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rdy: in STD_LOGIC; -- wait state input (read/write)
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so: in STD_LOGIC; -- set overflow V input
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rw: out STD_LOGIC; -- read/write out
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sync: out STD_LOGIC; -- opcode fetch out
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vp: out STD_LOGIC; -- vector pull
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ope: out STD_LOGIC; -- microcode end
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addr: out STD_LOGIC_VECTOR(15 downto 0); -- 16 bit address bus out
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data_in: in STD_LOGIC_VECTOR(7 downto 0); -- 8 bit input data bus
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data_out: out STD_LOGIC_VECTOR(7 downto 0) -- 8 bit output data bus
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);
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end v6502;
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architecture struct of v6502 is
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signal i_res: STD_LOGIC; -- internal global reset RES
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signal i_irq: STD_LOGIC; -- internal interrupt request IRQ
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signal i_nmi: STD_LOGIC; -- internal interrupt request NMI
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signal i_rdy: STD_LOGIC; -- internal wait request RDY
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signal i_so: STD_LOGIC; -- internal set overflow SO
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signal i_vp: STD_LOGIC; -- internal VP (vector pull)
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signal int: STD_LOGIC; -- internal global interrupt (instruction boundary synchronized)
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signal we: STD_LOGIC; -- write enable (combinatorial from PLA)
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signal we_r: STD_LOGIC; -- write enable (registered)
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signal ien: STD_LOGIC; -- interrupt IRQ enable
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-- microcode signals (register control)
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signal regop: STD_LOGIC_VECTOR(3 downto 0); -- register operation microcode
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signal rsel: STD_LOGIC_VECTOR(3 downto 0); -- register select microcode
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signal a_l: STD_LOGIC; -- A load
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signal x_l: STD_LOGIC; -- X load
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signal y_l: STD_LOGIC; -- Y load
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signal z_l: STD_LOGIC; -- Y load
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signal p_l: STD_LOGIC; -- P load
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signal o_l: STD_LOGIC; -- OPE load
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signal sp_ll: STD_LOGIC; -- SP load lsb
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signal sp_lh: STD_LOGIC; -- SP load msb
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signal sp_u: STD_LOGIC; -- SP increment
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signal sp_d: STD_LOGIC; -- SP decrement
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signal dmux_sel: STD_LOGIC_VECTOR(1 downto 0); -- ALU operand #2 data multiplexer
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-- microcode signals (ALU control)
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signal aluop: STD_LOGIC_VECTOR(4 downto 0); -- ALU operation code
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-- microcode signals CPU control logic
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signal opfetch: STD_LOGIC; -- opcode fetch
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signal i_sync: STD_LOGIC; -- internal SYNC not latched
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signal m_sync: STD_LOGIC; -- internal SYNC latched
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signal opdec: STD_LOGIC; -- opcode decode
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signal pcmp: STD_LOGIC_VECTOR(1 downto 0); -- PC/MP out control effective
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signal pcmp_mc: STD_LOGIC_VECTOR(1 downto 0); -- PC/MP out control microcode
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signal pcinc: STD_LOGIC; -- PC increment
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signal e_eop: STD_LOGIC; -- early microcode sequence end (for some opcodes)
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signal mc_eop: STD_LOGIC; -- microcode sequence end (for some opcodes)
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signal eop: STD_LOGIC; -- microcode sequence end (effective)
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signal we_mc: STD_LOGIC; -- microcode write enable
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signal we_mc_l: STD_LOGIC; -- microcode write enable to latch
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signal fbrk: STD_LOGIC; -- force BRK opcode (used by hardware interrupts)
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signal opbrk: STD_LOGIC; -- BRK opcode (used for distinguish between hardware/software interrupts)
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signal bcf: STD_LOGIC; -- branch condition resolved
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signal pcc: STD_LOGIC; -- PC carry
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signal clri: STD_LOGIC; -- clear interrupt request pending microcode
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signal vso: STD_LOGIC; -- SO input high to low edge flag
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signal mc_branch: STD_LOGIC; -- branch (relative) opcode
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signal adc_sbc_mc: STD_LOGIC; -- ADC/SBC opcode (used for decimal adjustment)
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signal ai_op: STD_LOGIC; -- opcode with absolute indexed addressing mode
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signal daa_req: STD_LOGIC; -- DAA required
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signal mcad: STD_LOGIC_VECTOR(10 downto 0); -- microcode address
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signal mcscan: STD_LOGIC_VECTOR(2 downto 0); -- microcode pointer control
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signal p_op: STD_LOGIC_VECTOR(3 downto 0); -- microcode control bits register P
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signal pcr_fc: STD_LOGIC_VECTOR(2 downto 0); -- microcode control PC
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signal mpr_fc: STD_LOGIC_VECTOR(3 downto 0); -- microcode control MP
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signal mcbit: STD_LOGIC_VECTOR(34 downto 0); -- microcode control bits
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signal regbit: STD_LOGIC_VECTOR(8 downto 0); -- microcode control bits
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signal ivoffs: STD_LOGIC_VECTOR(2 downto 0); -- microcode interrupt vector offset encoding
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signal mcn: STD_LOGIC; -- microcode does NOPs
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signal add_sub_op: STD_LOGIC; -- ADC/SBC opcode
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-- ALU signals
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signal bcd: STD_LOGIC; -- ALU binary/bcd mode
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signal c_flg: STD_LOGIC; -- ALU carry flag
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signal z_flg: STD_LOGIC; -- ALU zero flag
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signal v_flg: STD_LOGIC; -- ALU overflow flag
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signal n_flg: STD_LOGIC; -- ALU negative flag
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signal pc_c_alu_flg: STD_LOGIC; -- ALU PC carry flag
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signal acr_reg: STD_LOGIC; -- ALU auxiliary carry (registered)
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signal bcd_lsb: STD_LOGIC; -- bcd lsb overflow flag
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signal bcd_msb: STD_LOGIC; -- bcd msb overflow flag
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signal branch_neg: STD_LOGIC; -- branch negative offset flag
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-- bus
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signal dbin: STD_LOGIC_VECTOR(7 downto 0); -- input data bus D0..D7
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signal dbout: STD_LOGIC_VECTOR(7 downto 0); -- output data bus D0..D7
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signal a_bus: STD_LOGIC_VECTOR(7 downto 0); -- accumulator register A bus
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signal x_bus: STD_LOGIC_VECTOR(7 downto 0); -- index register X bus
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signal y_bus: STD_LOGIC_VECTOR(7 downto 0); -- index register Y bus
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signal z_bus: STD_LOGIC_VECTOR(7 downto 0); -- index register Z bus
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signal sp_bus: STD_LOGIC_VECTOR(15 downto 0); -- stack pointer register S bus
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signal p_bus: STD_LOGIC_VECTOR(7 downto 0); -- status register P bus
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signal op_bus: STD_LOGIC_VECTOR(7 downto 0); -- opcode register bus
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signal o_bus: STD_LOGIC_VECTOR(7 downto 0); -- operand register bus
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signal bcd_bus: STD_LOGIC_VECTOR(7 downto 0); -- bcd constants bus (used for decimal adjustement)
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signal oper_bus: STD_LOGIC_VECTOR(7 downto 0); -- operand bus (ALU operand #2 bus)
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signal r_bus: STD_LOGIC_VECTOR(7 downto 0); -- general register bus (ALU operand #2 bus)
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signal alu_bus: STD_LOGIC_VECTOR(7 downto 0); -- ALU output bus
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signal pc_bus: STD_LOGIC_VECTOR(15 downto 0); -- program counter register PC bus
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signal mp_bus: STD_LOGIC_VECTOR(15 downto 0); -- memory pointer register PC bus
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signal ad_bus: STD_LOGIC_VECTOR(15 downto 0); -- address bus
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-- 16 bit program counter register (PC)
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component pcr
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port( clk: in STD_LOGIC; -- clock
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i: in STD_LOGIC; -- increment
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fwait: in STD_LOGIC; -- wait
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fc: in STD_LOGIC_VECTOR(3 downto 0); -- function code
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din1: in STD_LOGIC_VECTOR(7 downto 0); -- input
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din2: in STD_LOGIC_VECTOR(7 downto 0); -- input
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dout: out STD_LOGIC_VECTOR(15 downto 0) -- output
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);
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end component;
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-- 16 bit memory pointer register (MP)
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component mpr
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port( clk: in STD_LOGIC; -- clock
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fwait: in STD_LOGIC; -- wait
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c: in STD_LOGIC; -- carry input
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fc: in STD_LOGIC_VECTOR(3 downto 0); -- function code
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din_l: in STD_LOGIC_VECTOR(7 downto 0); -- input LSB
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din_h: in STD_LOGIC_VECTOR(7 downto 0); -- input MSB
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zp: in STD_LOGIC_VECTOR(7 downto 0); -- input zero bage register Z
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v: in STD_LOGIC_VECTOR(2 downto 0); -- vector offset input
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dout: out STD_LOGIC_VECTOR(15 downto 0) -- output
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);
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end component;
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-- 8 bit opcode register opr (pipeline opcode prefetch register)
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component opr
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port( clk: in STD_LOGIC; -- clock
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clr: in STD_LOGIC; -- force BRK opcode
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fwait: in STD_LOGIC; -- wait
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ld: in STD_LOGIC; -- load
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din: in STD_LOGIC_VECTOR(7 downto 0); -- input
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b: out STD_LOGIC; -- BRK opcode
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dout: out STD_LOGIC_VECTOR(7 downto 0) -- output
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);
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end component;
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-- 8 bit operand hold register oper
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component oper
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port( clk: in STD_LOGIC; -- clock
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fwait: in STD_LOGIC; -- wait
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ld: in STD_LOGIC; -- load
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din: in STD_LOGIC_VECTOR(7 downto 0); -- input
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dout: out STD_LOGIC_VECTOR(7 downto 0) -- output
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);
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end component;
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-- 8 bit accumulator register A
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component ar
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port( clk: in STD_LOGIC; -- clock
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fwait: in STD_LOGIC;
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ld: in STD_LOGIC; -- load
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din: in STD_LOGIC_VECTOR(7 downto 0); -- input
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dout: out STD_LOGIC_VECTOR(7 downto 0) -- output
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);
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end component;
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-- 8 bit index register X
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component xr
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port( clk: in STD_LOGIC; -- clock
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fwait: in STD_LOGIC;
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ld: in STD_LOGIC; -- load
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din: in STD_LOGIC_VECTOR(7 downto 0); -- input
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| 191 |
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dout: out STD_LOGIC_VECTOR(7 downto 0) -- output
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);
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end component;
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-- 8 bit index register Y
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component yr
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port( clk: in STD_LOGIC; -- clock
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fwait: in STD_LOGIC;
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ld: in STD_LOGIC; -- load
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| 200 |
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din: in STD_LOGIC_VECTOR(7 downto 0); -- input
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dout: out STD_LOGIC_VECTOR(7 downto 0) -- output
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);
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end component;
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-- 8 bit zero page register Z
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-- cleared by any interrupts
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component zr
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port( clk: in STD_LOGIC; -- clock
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clr: in STD_LOGIC; -- reset
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fwait: in STD_LOGIC;
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ld: in STD_LOGIC; -- load
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| 212 |
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din: in STD_LOGIC_VECTOR(7 downto 0); -- input
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| 213 |
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dout: out STD_LOGIC_VECTOR(7 downto 0) -- output
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);
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end component;
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-- 16 bit stack pointer SP
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component spr
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port( clk: in STD_LOGIC; -- clock
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| 220 |
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fwait: in STD_LOGIC; -- wait
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| 221 |
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clr: in STD_LOGIC; -- load init value
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| 222 |
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ld_l: in STD_LOGIC; -- load lsb
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| 223 |
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ld_h: in STD_LOGIC; -- load msb
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| 224 |
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u: in STD_LOGIC; -- increment
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| 225 |
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d: in STD_LOGIC; -- decrement
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| 226 |
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din: in STD_LOGIC_VECTOR(7 downto 0); -- input
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| 227 |
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dout: out STD_LOGIC_VECTOR(15 downto 0) -- output
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| 228 |
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);
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end component;
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| 230 |
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| 231 |
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-- 8 bit processor status register P
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| 232 |
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-- NV1BDIZC
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| 233 |
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-- 76543210
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| 234 |
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-- ||||||||
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| 235 |
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-- ||||||||--- C = carry/borrow flag
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| 236 |
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-- |||||||---- Z = zero flag
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| 237 |
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-- ||||||----- I = interrupt mask
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| 238 |
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-- |||||------ D = decimal/binary alu mode
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| 239 |
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-- ||||------- B = break opcode flag
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| 240 |
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-- |||-------- 1 = always "1'
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| 241 |
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-- ||--------- V = overflow flag
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| 242 |
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-- |---------- N = negative flag
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| 243 |
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-- The P register also contains an additional carry/borrow flag (ACR) used for effective address calculation but
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| 244 |
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-- it is not visible at program level
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| 245 |
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component pr
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| 246 |
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port( clk: in STD_LOGIC; -- clock
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| 247 |
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clr: in STD_LOGIC; -- clear
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| 248 |
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fwait: in STD_LOGIC; -- wait
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| 249 |
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n: in STD_LOGIC; -- N input
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| 250 |
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v: in STD_LOGIC; -- V input
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| 251 |
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z: in STD_LOGIC; -- Z input
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| 252 |
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c: in STD_LOGIC; -- C input
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| 253 |
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b: in STD_LOGIC; -- B input
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| 254 |
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sv: in STD_LOGIC; -- set overflow
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| 255 |
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acr_in: in STD_LOGIC; -- auxiliary carry in
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| 256 |
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fc: in STD_LOGIC_VECTOR(3 downto 0); -- function code
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| 257 |
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din: in STD_LOGIC_VECTOR(7 downto 0); -- input
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| 258 |
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dout: out STD_LOGIC_VECTOR(7 downto 0); -- output
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| 259 |
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acr_out: out STD_LOGIC -- auxiliary carry out
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| 260 |
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);
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| 261 |
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end component;
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| 262 |
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| 263 |
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-- BCD register (used for decimal adjustement)
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| 264 |
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component bcd_reg is
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| 265 |
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port( clk: in STD_LOGIC;
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| 266 |
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clr: in STD_LOGIC;
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| 267 |
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fwait: in STD_LOGIC;
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| 268 |
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en: in STD_LOGIC;
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| 269 |
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bcd_sl: in STD_LOGIC; -- loads "6" to lsb
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| 270 |
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bcd_sh: in STD_LOGIC; -- loads "6" to msb
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| 271 |
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dout: out STD_LOGIC_VECTOR(7 downto 0)
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| 272 |
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);
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| 273 |
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end component;
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| 274 |
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| 275 |
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-- 8 bit (binary/bcd) two-way through pass ALU
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| 276 |
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-- operation:
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| 277 |
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-- aluop = "0000" => dout <= op1 (pass/test)
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| 278 |
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-- aluop = "0001" => dout <= op1 + op2 + carry
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| 279 |
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-- aluop = "0010" => dout <= op1 - op2 - carry
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| 280 |
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-- aluop = "0011" => dout <= op1 and op2
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| 281 |
|
|
-- aluop = "0100" => dout <= op1 or op2
|
| 282 |
|
|
-- aluop = "0101" => dout <= op1 xor op2
|
| 283 |
|
|
-- aluop = "0110" => dout <= op1 + 1
|
| 284 |
|
|
-- aluop = "0111" => dout <= op1 - 1
|
| 285 |
|
|
-- aluop = "1000" => dout <= op1 << 1 (ASL)
|
| 286 |
|
|
-- aluop = "1001" => dout <= op1 >> 1 (LSR)
|
| 287 |
|
|
-- aluop = "1010" => dout <= op1 << 1 (ROL)
|
| 288 |
|
|
-- aluop = "1011" => dout <= op1 >> 1 (ROR)
|
| 289 |
|
|
component alu_bin
|
| 290 |
|
|
port( alu_byp: in STD_LOGIC; -- ALU bypass (no operation)
|
| 291 |
|
|
cin: in STD_LOGIC; -- carry/borrow in
|
| 292 |
|
|
vin: in STD_LOGIC; -- overflow in
|
| 293 |
|
|
op1: in STD_LOGIC_VECTOR(7 downto 0); -- 8 bit operand #1
|
| 294 |
|
|
op2: in STD_LOGIC_VECTOR(7 downto 0); -- 8 bit operand #2
|
| 295 |
|
|
fc: in STD_LOGIC_VECTOR(5 downto 0); -- function code
|
| 296 |
|
|
cf: out STD_LOGIC; -- carry/borrow (byte) out
|
| 297 |
|
|
zf: out STD_LOGIC; -- zero flag out
|
| 298 |
|
|
nf: out STD_LOGIC; -- negative flag out
|
| 299 |
|
|
vf: out STD_LOGIC; -- overflow flag out
|
| 300 |
|
|
pc_cf: out STD_LOGIC; -- carry/borrow out for PC operation
|
| 301 |
|
|
bcd_ol: out STD_LOGIC; -- bcd lsb overflow
|
| 302 |
|
|
bcd_oh: out STD_LOGIC; -- bcd msb overflow
|
| 303 |
|
|
dout: out STD_LOGIC_VECTOR(7 downto 0) -- 8 bit result out
|
| 304 |
|
|
);
|
| 305 |
|
|
end component;
|
| 306 |
|
|
|
| 307 |
|
|
-- PC/MP address multiplexer
|
| 308 |
|
|
component addrmux
|
| 309 |
|
|
port( sel: in STD_LOGIC_VECTOR(1 downto 0);
|
| 310 |
|
|
a: in STD_LOGIC_VECTOR(15 downto 0);
|
| 311 |
|
|
b: in STD_LOGIC_VECTOR(15 downto 0);
|
| 312 |
|
|
s: in STD_LOGIC_VECTOR(15 downto 0);
|
| 313 |
|
|
y: out STD_LOGIC_VECTOR(15 downto 0)
|
| 314 |
|
|
);
|
| 315 |
|
|
end component;
|
| 316 |
|
|
|
| 317 |
|
|
-- register multiplexer
|
| 318 |
|
|
component regmux
|
| 319 |
|
|
port( sel: in STD_LOGIC_VECTOR(3 downto 0);
|
| 320 |
|
|
a: in STD_LOGIC_VECTOR(7 downto 0);
|
| 321 |
|
|
b: in STD_LOGIC_VECTOR(7 downto 0);
|
| 322 |
|
|
c: in STD_LOGIC_VECTOR(7 downto 0);
|
| 323 |
|
|
d: in STD_LOGIC_VECTOR(7 downto 0);
|
| 324 |
|
|
e: in STD_LOGIC_VECTOR(7 downto 0);
|
| 325 |
|
|
f: in STD_LOGIC_VECTOR(7 downto 0);
|
| 326 |
|
|
g: in STD_LOGIC_VECTOR(7 downto 0);
|
| 327 |
|
|
h: in STD_LOGIC_VECTOR(7 downto 0);
|
| 328 |
|
|
i: in STD_LOGIC_VECTOR(7 downto 0);
|
| 329 |
|
|
j: in STD_LOGIC_VECTOR(7 downto 0);
|
| 330 |
|
|
k: in STD_LOGIC_VECTOR(7 downto 0);
|
| 331 |
|
|
y: out STD_LOGIC_VECTOR(7 downto 0)
|
| 332 |
|
|
);
|
| 333 |
|
|
end component;
|
| 334 |
|
|
|
| 335 |
|
|
-- data multiplexer (register "O" bypass)
|
| 336 |
|
|
component dmux is
|
| 337 |
|
|
port( sel: in STD_LOGIC_VECTOR(1 downto 0);
|
| 338 |
|
|
a: in STD_LOGIC_VECTOR(7 downto 0);
|
| 339 |
|
|
b: in STD_LOGIC_VECTOR(7 downto 0);
|
| 340 |
|
|
c: in STD_LOGIC_VECTOR(7 downto 0);
|
| 341 |
|
|
y: out STD_LOGIC_VECTOR(7 downto 0)
|
| 342 |
|
|
);
|
| 343 |
|
|
end component dmux;
|
| 344 |
|
|
|
| 345 |
|
|
-- microcode sequencer logic
|
| 346 |
|
|
component mcseq
|
| 347 |
|
|
port( clk: in STD_LOGIC;
|
| 348 |
|
|
clr: in STD_LOGIC;
|
| 349 |
|
|
mc_nop: in STD_LOGIC;
|
| 350 |
|
|
fwait: in STD_LOGIC;
|
| 351 |
|
|
q: out STD_LOGIC_VECTOR(2 downto 0)
|
| 352 |
|
|
);
|
| 353 |
|
|
end component;
|
| 354 |
|
|
|
| 355 |
|
|
-- micropla logic
|
| 356 |
|
|
-- output fields format:
|
| 357 |
|
|
component mcpla
|
| 358 |
|
|
port( a: in STD_LOGIC_VECTOR(10 downto 0);
|
| 359 |
|
|
q: out STD_LOGIC_VECTOR(34 downto 0)
|
| 360 |
|
|
);
|
| 361 |
|
|
end component;
|
| 362 |
|
|
|
| 363 |
|
|
-- register operation decoding logic
|
| 364 |
|
|
component decreg
|
| 365 |
|
|
port( r: in STD_LOGIC_VECTOR(3 downto 0);
|
| 366 |
|
|
y: out STD_LOGIC_VECTOR(8 downto 0)
|
| 367 |
|
|
);
|
| 368 |
|
|
end component;
|
| 369 |
|
|
|
| 370 |
|
|
-- cpu main state machine
|
| 371 |
|
|
component cpufsm
|
| 372 |
|
|
port( clk: in STD_LOGIC;
|
| 373 |
|
|
clr: in STD_LOGIC;
|
| 374 |
|
|
fwait: in STD_LOGIC;
|
| 375 |
|
|
ireq: in STD_LOGIC;
|
| 376 |
|
|
branch: in STD_LOGIC;
|
| 377 |
|
|
bflag: in STD_LOGIC;
|
| 378 |
|
|
aim: in STD_LOGIC;
|
| 379 |
|
|
bcarry: in STD_LOGIC;
|
| 380 |
|
|
icarry: in STD_LOGIC;
|
| 381 |
|
|
p1: in STD_LOGIC_VECTOR(1 downto 0);
|
| 382 |
|
|
e_ei: in STD_LOGIC;
|
| 383 |
|
|
mc_ei: in STD_LOGIC;
|
| 384 |
|
|
addsub: in STD_LOGIC;
|
| 385 |
|
|
dec_mode: in STD_LOGIC;
|
| 386 |
|
|
fetch: out STD_LOGIC;
|
| 387 |
|
|
op_sync: out STD_LOGIC;
|
| 388 |
|
|
pci: out STD_LOGIC;
|
| 389 |
|
|
pq: out STD_LOGIC_VECTOR(1 downto 0);
|
| 390 |
|
|
fb: out STD_LOGIC;
|
| 391 |
|
|
od: out STD_LOGIC;
|
| 392 |
|
|
mc_nop: out STD_LOGIC
|
| 393 |
|
|
);
|
| 394 |
|
|
end component;
|
| 395 |
|
|
|
| 396 |
|
|
-- interrupt logic
|
| 397 |
|
|
component intlog
|
| 398 |
|
|
port( clk: in STD_LOGIC;
|
| 399 |
|
|
iack: in STD_LOGIC; -- interrupt acknowledge by microcode
|
| 400 |
|
|
r: in STD_LOGIC; -- RESET request
|
| 401 |
|
|
n: in STD_LOGIC; -- NMI request
|
| 402 |
|
|
i: in STD_LOGIC; -- IRQ request
|
| 403 |
|
|
b: in STD_LOGIC; -- BRK opcode
|
| 404 |
|
|
s: in STD_LOGIC; -- SO
|
| 405 |
|
|
imask: in STD_LOGIC; -- interrupt mask (valid only for IRQ)
|
| 406 |
|
|
ioffs: in STD_LOGIC_VECTOR(1 downto 0); -- interrupt servicing offset
|
| 407 |
|
|
ireq: out STD_LOGIC; -- global interrupt requestb (IRQ/NMI)
|
| 408 |
|
|
vset: out STD_LOGIC; -- SO output
|
| 409 |
|
|
voffs: out STD_LOGIC_VECTOR(2 downto 0) -- interrupt vector offset
|
| 410 |
|
|
);
|
| 411 |
|
|
end component;
|
| 412 |
|
|
|
| 413 |
|
|
-- branch logic
|
| 414 |
|
|
component branch
|
| 415 |
|
|
port( op: in STD_LOGIC_VECTOR(3 downto 0);
|
| 416 |
|
|
n: in STD_LOGIC;
|
| 417 |
|
|
v: in STD_LOGIC;
|
| 418 |
|
|
z: in STD_LOGIC;
|
| 419 |
|
|
c: in STD_LOGIC;
|
| 420 |
|
|
bres: out STD_LOGIC
|
| 421 |
|
|
);
|
| 422 |
|
|
end component;
|
| 423 |
|
|
|
| 424 |
|
|
-- opcode decimal instructions and prefetch prediction logic
|
| 425 |
|
|
component pre_dec
|
| 426 |
|
|
port( op: in STD_LOGIC_VECTOR(7 downto 0);
|
| 427 |
|
|
fetch: in STD_LOGIC;
|
| 428 |
|
|
ei: out STD_LOGIC;
|
| 429 |
|
|
dec: out STD_LOGIC
|
| 430 |
|
|
);
|
| 431 |
|
|
end component;
|
| 432 |
|
|
|
| 433 |
|
|
begin
|
| 434 |
|
|
u1:pcr port map(clk=>clk0,
|
| 435 |
|
|
i=>pcinc,
|
| 436 |
|
|
fwait=>i_rdy,
|
| 437 |
|
|
fc(3 downto 1)=>pcr_fc,
|
| 438 |
|
|
fc(0)=>o_bus(7),
|
| 439 |
|
|
din1=>alu_bus,
|
| 440 |
|
|
din2=>o_bus,
|
| 441 |
|
|
dout=>pc_bus
|
| 442 |
|
|
);
|
| 443 |
|
|
|
| 444 |
|
|
u2:mpr port map(clk=>clk0,
|
| 445 |
|
|
fwait=>i_rdy,
|
| 446 |
|
|
c=>acr_reg,
|
| 447 |
|
|
fc=>mpr_fc,
|
| 448 |
|
|
din_l=>alu_bus,
|
| 449 |
|
|
din_h=>dbin,
|
| 450 |
|
|
zp=>z_bus,
|
| 451 |
|
|
v=>ivoffs,
|
| 452 |
|
|
dout=>mp_bus
|
| 453 |
|
|
);
|
| 454 |
|
|
|
| 455 |
|
|
u3:ar port map(clk=>clk0,
|
| 456 |
|
|
fwait=>i_rdy,
|
| 457 |
|
|
ld=>a_l,
|
| 458 |
|
|
din=>alu_bus,
|
| 459 |
|
|
dout=>a_bus
|
| 460 |
|
|
);
|
| 461 |
|
|
|
| 462 |
|
|
u4:xr port map(clk=>clk0,
|
| 463 |
|
|
fwait=>i_rdy,
|
| 464 |
|
|
ld=>x_l,
|
| 465 |
|
|
din=>alu_bus,
|
| 466 |
|
|
dout=>x_bus
|
| 467 |
|
|
);
|
| 468 |
|
|
|
| 469 |
|
|
u5:yr port map(clk=>clk0,
|
| 470 |
|
|
fwait=>i_rdy,
|
| 471 |
|
|
ld=>y_l,
|
| 472 |
|
|
din=>alu_bus,
|
| 473 |
|
|
dout=>y_bus
|
| 474 |
|
|
);
|
| 475 |
|
|
|
| 476 |
|
|
u6:zr port map(clk=>clk0,
|
| 477 |
|
|
clr=>clri,
|
| 478 |
|
|
fwait=>i_rdy,
|
| 479 |
|
|
ld=>z_l,
|
| 480 |
|
|
din=>alu_bus,
|
| 481 |
|
|
dout=>z_bus
|
| 482 |
|
|
);
|
| 483 |
|
|
|
| 484 |
|
|
u7:spr port map(clk=>clk0,
|
| 485 |
|
|
clr=>i_res,
|
| 486 |
|
|
fwait=>i_rdy,
|
| 487 |
|
|
ld_l=>sp_ll,
|
| 488 |
|
|
ld_h=>sp_lh,
|
| 489 |
|
|
u=>sp_u,
|
| 490 |
|
|
d=>sp_d,
|
| 491 |
|
|
din=>alu_bus,
|
| 492 |
|
|
dout=>sp_bus
|
| 493 |
|
|
);
|
| 494 |
|
|
|
| 495 |
|
|
u8:pr port map(clk=>clk0,
|
| 496 |
|
|
clr=>i_res,
|
| 497 |
|
|
fwait=>i_rdy,
|
| 498 |
|
|
n=>n_flg,
|
| 499 |
|
|
v=>v_flg,
|
| 500 |
|
|
z=>z_flg,
|
| 501 |
|
|
c=>c_flg,
|
| 502 |
|
|
b=>opbrk,
|
| 503 |
|
|
sv=>vso,
|
| 504 |
|
|
acr_in=>pc_c_alu_flg,
|
| 505 |
|
|
fc=>p_op,
|
| 506 |
|
|
din=>dbin,
|
| 507 |
|
|
dout=>p_bus,
|
| 508 |
|
|
acr_out=>acr_reg
|
| 509 |
|
|
);
|
| 510 |
|
|
|
| 511 |
|
|
u9:opr port map(clk=>clk0,
|
| 512 |
|
|
clr=>fbrk,
|
| 513 |
|
|
fwait=>i_rdy,
|
| 514 |
|
|
ld=>opfetch,
|
| 515 |
|
|
din=>dbin,
|
| 516 |
|
|
b=>opbrk,
|
| 517 |
|
|
dout=>op_bus
|
| 518 |
|
|
);
|
| 519 |
|
|
|
| 520 |
|
|
u10:oper port map(clk=>clk0,
|
| 521 |
|
|
fwait=>i_rdy,
|
| 522 |
|
|
ld=>o_l,
|
| 523 |
|
|
din=>alu_bus,
|
| 524 |
|
|
dout=>o_bus
|
| 525 |
|
|
);
|
| 526 |
|
|
|
| 527 |
|
|
u11:bcd_reg port map(clk=>clk0,
|
| 528 |
|
|
clr=>opfetch,
|
| 529 |
|
|
fwait=>i_rdy,
|
| 530 |
|
|
en=>bcd,
|
| 531 |
|
|
bcd_sl=>bcd_lsb,
|
| 532 |
|
|
bcd_sh=>bcd_msb,
|
| 533 |
|
|
dout=>bcd_bus
|
| 534 |
|
|
);
|
| 535 |
|
|
|
| 536 |
|
|
u12:alu_bin port map(alu_byp=>acr_reg,
|
| 537 |
|
|
cin=>p_bus(0),
|
| 538 |
|
|
vin=>p_bus(6),
|
| 539 |
|
|
op1=>r_bus,
|
| 540 |
|
|
op2=>oper_bus,
|
| 541 |
|
|
fc(5 downto 1)=>aluop,
|
| 542 |
|
|
fc(0)=>branch_neg,
|
| 543 |
|
|
cf=>c_flg,
|
| 544 |
|
|
zf=>z_flg,
|
| 545 |
|
|
nf=>n_flg,
|
| 546 |
|
|
vf=>v_flg,
|
| 547 |
|
|
pc_cf=>pc_c_alu_flg,
|
| 548 |
|
|
bcd_ol=>bcd_lsb,
|
| 549 |
|
|
bcd_oh=>bcd_msb,
|
| 550 |
|
|
dout=>alu_bus
|
| 551 |
|
|
);
|
| 552 |
|
|
|
| 553 |
|
|
u13:addrmux port map(sel=>pcmp,
|
| 554 |
|
|
a=>pc_bus,
|
| 555 |
|
|
b=>mp_bus,
|
| 556 |
|
|
s=>sp_bus,
|
| 557 |
|
|
y=>addr
|
| 558 |
|
|
);
|
| 559 |
|
|
|
| 560 |
|
|
u14:regmux port map(sel=>rsel,
|
| 561 |
|
|
a=>dbin,
|
| 562 |
|
|
b=>a_bus,
|
| 563 |
|
|
c=>x_bus,
|
| 564 |
|
|
d=>y_bus,
|
| 565 |
|
|
e=>sp_bus(7 downto 0),
|
| 566 |
|
|
f=>sp_bus(15 downto 8),
|
| 567 |
|
|
g=>p_bus,
|
| 568 |
|
|
h=>pc_bus(7 downto 0),
|
| 569 |
|
|
i=>pc_bus(15 downto 8),
|
| 570 |
|
|
j=>o_bus,
|
| 571 |
|
|
k=>z_bus,
|
| 572 |
|
|
y=>r_bus
|
| 573 |
|
|
);
|
| 574 |
|
|
|
| 575 |
|
|
u15:dmux port map(sel=>dmux_sel,
|
| 576 |
|
|
a=>o_bus,
|
| 577 |
|
|
b=>dbin,
|
| 578 |
|
|
c=>bcd_bus,
|
| 579 |
|
|
y=>oper_bus
|
| 580 |
|
|
);
|
| 581 |
|
|
|
| 582 |
|
|
u16:mcseq port map(clk=>clk0,
|
| 583 |
|
|
clr=>opdec,
|
| 584 |
|
|
mc_nop=>mcn,
|
| 585 |
|
|
fwait=>i_rdy,
|
| 586 |
|
|
q=>mcscan
|
| 587 |
|
|
);
|
| 588 |
|
|
|
| 589 |
|
|
u17:mcpla port map(a=>mcad,
|
| 590 |
|
|
q=>mcbit
|
| 591 |
|
|
);
|
| 592 |
|
|
|
| 593 |
|
|
u18:decreg port map(r=>regop,
|
| 594 |
|
|
y=>regbit
|
| 595 |
|
|
);
|
| 596 |
|
|
|
| 597 |
|
|
u19:cpufsm port map(clk=>clk0,
|
| 598 |
|
|
clr=>i_res,
|
| 599 |
|
|
fwait=>i_rdy,
|
| 600 |
|
|
ireq=>int,
|
| 601 |
|
|
branch=>mc_branch,
|
| 602 |
|
|
bflag=>bcf,
|
| 603 |
|
|
aim=>ai_op,
|
| 604 |
|
|
bcarry=>pcc,
|
| 605 |
|
|
icarry=>acr_reg,
|
| 606 |
|
|
p1=>pcmp_mc,
|
| 607 |
|
|
e_ei=>e_eop,
|
| 608 |
|
|
mc_ei=>mc_eop,
|
| 609 |
|
|
addsub=>add_sub_op,
|
| 610 |
|
|
dec_mode=>p_bus(3),
|
| 611 |
|
|
fetch=>opfetch,
|
| 612 |
|
|
op_sync=>i_sync,
|
| 613 |
|
|
pci=>pcinc,
|
| 614 |
|
|
pq=>pcmp,
|
| 615 |
|
|
fb=>fbrk,
|
| 616 |
|
|
od=>opdec,
|
| 617 |
|
|
mc_nop=>mcn
|
| 618 |
|
|
);
|
| 619 |
|
|
|
| 620 |
|
|
u20:intlog port map(clk=>clk0,
|
| 621 |
|
|
iack=>clri,
|
| 622 |
|
|
r=>i_res,
|
| 623 |
|
|
n=>i_nmi,
|
| 624 |
|
|
i=>i_irq,
|
| 625 |
|
|
b=>opbrk,
|
| 626 |
|
|
s=>i_so,
|
| 627 |
|
|
imask=>ien,
|
| 628 |
|
|
ioffs=>mp_bus(2 downto 1),
|
| 629 |
|
|
ireq=>int,
|
| 630 |
|
|
vset=>vso,
|
| 631 |
|
|
voffs=>ivoffs
|
| 632 |
|
|
);
|
| 633 |
|
|
|
| 634 |
|
|
u21:branch port map(op=>op_bus(7 downto 4),
|
| 635 |
|
|
n=>p_bus(7),
|
| 636 |
|
|
v=>p_bus(6),
|
| 637 |
|
|
z=>p_bus(1),
|
| 638 |
|
|
c=>p_bus(0),
|
| 639 |
|
|
bres=>bcf
|
| 640 |
|
|
);
|
| 641 |
|
|
|
| 642 |
|
|
u22:pre_dec port map(op=>dbin,
|
| 643 |
|
|
fetch=>opfetch,
|
| 644 |
|
|
ei=>e_eop,
|
| 645 |
|
|
dec=>add_sub_op
|
| 646 |
|
|
);
|
| 647 |
|
|
|
| 648 |
|
|
-- asynchronous CPU link section
|
| 649 |
|
|
ien <= p_bus(2); -- P(I) flag
|
| 650 |
|
|
bcd <= p_bus(3); -- P(D) flag
|
| 651 |
|
|
i_res <= not res; -- internal reset
|
| 652 |
|
|
i_nmi <= not nmi; -- internal NMI
|
| 653 |
|
|
i_irq <= not irq; -- internal IRQ
|
| 654 |
|
|
i_rdy <= not rdy; -- internal RDY
|
| 655 |
|
|
i_so <= not so; -- internal SO
|
| 656 |
|
|
mcad <= op_bus & mcscan; -- microcode address
|
| 657 |
|
|
rsel <= mcbit(3 downto 0); -- registers read microcode
|
| 658 |
|
|
regop <= mcbit(7 downto 4); -- registers operation microcode
|
| 659 |
|
|
aluop <= mcbit(12 downto 8); -- ALU microcode
|
| 660 |
|
|
p_op <= mcbit(16 downto 13); -- register P microcode
|
| 661 |
|
|
mpr_fc <= mcbit(20 downto 17); -- MPR microcode
|
| 662 |
|
|
pcr_fc <= mcbit(23 downto 21); -- PCR microcode
|
| 663 |
|
|
pcmp_mc <= mcbit(25 downto 24); -- PCR/MPR multiplexer microcode
|
| 664 |
|
|
clri <= mcbit(26); -- clear interrupt request (also serves as register Z clear)
|
| 665 |
|
|
we_mc <= mcbit(27); -- write enable (combinatorial) microcode
|
| 666 |
|
|
we_mc_l <= mcbit(28); -- write enable (latched) microcode
|
| 667 |
|
|
mc_eop <= mcbit(29); -- end of instruction reached
|
| 668 |
|
|
mc_branch <= mcbit(30); -- branch opcode
|
| 669 |
|
|
i_vp <= mcbit(31); -- vector pull
|
| 670 |
|
|
ai_op <= mcbit(32); -- opcode with addressing indexed microcode
|
| 671 |
|
|
dmux_sel <= mcbit(34 downto 33); -- data multiplexer microcode
|
| 672 |
|
|
ope <= eop;
|
| 673 |
|
|
eop <= '1' when mc_eop = '1' or e_eop = '1' else '0';
|
| 674 |
|
|
branch_neg <= '0' when mc_branch = '0' else o_bus(7); -- flag for branch negative offset is valid only with branches opcode
|
| 675 |
|
|
vp <= not i_vp;
|
| 676 |
|
|
|
| 677 |
|
|
-- register operations
|
| 678 |
|
|
a_l <= regbit(0); -- A load
|
| 679 |
|
|
x_l <= regbit(1); -- X load
|
| 680 |
|
|
y_l <= regbit(2); -- Y load
|
| 681 |
|
|
z_l <= regbit(3); -- Z load
|
| 682 |
|
|
o_l <= regbit(4); -- O load
|
| 683 |
|
|
sp_ll <= regbit(5); -- S load lsb
|
| 684 |
|
|
sp_lh <= regbit(6); -- S load msb
|
| 685 |
|
|
sp_u <= regbit(7); -- S += 1
|
| 686 |
|
|
sp_d <= regbit(8); -- S -= 1
|
| 687 |
|
|
we <= we_mc or opfetch; -- write enable
|
| 688 |
|
|
sync <= m_sync;
|
| 689 |
|
|
|
| 690 |
|
|
-- SYNC latched
|
| 691 |
|
|
process(clk0)
|
| 692 |
|
|
begin
|
| 693 |
|
|
if (clk0'event and clk0 = '1') then
|
| 694 |
|
|
if i_rdy = '0' then
|
| 695 |
|
|
m_sync <= i_sync;
|
| 696 |
|
|
else
|
| 697 |
|
|
m_sync <= m_sync;
|
| 698 |
|
|
end if;
|
| 699 |
|
|
end if;
|
| 700 |
|
|
end process;
|
| 701 |
|
|
|
| 702 |
|
|
-- PC carry logic
|
| 703 |
|
|
process(o_bus,pc_c_alu_flg)
|
| 704 |
|
|
begin
|
| 705 |
|
|
if o_bus(7) = '0' then -- check for positive/negative branch offset (bit 7)
|
| 706 |
|
|
pcc <= pc_c_alu_flg;
|
| 707 |
|
|
else
|
| 708 |
|
|
pcc <= not pc_c_alu_flg;
|
| 709 |
|
|
end if;
|
| 710 |
|
|
end process;
|
| 711 |
|
|
|
| 712 |
|
|
-- write enable registered
|
| 713 |
|
|
process(clk0)
|
| 714 |
|
|
begin
|
| 715 |
|
|
if (clk0'event and clk0 = '1') then
|
| 716 |
|
|
if i_res = '1' then
|
| 717 |
|
|
we_r <= '1';
|
| 718 |
|
|
else
|
| 719 |
|
|
if i_rdy = '0' then
|
| 720 |
|
|
we_r <= we_mc_l;
|
| 721 |
|
|
else
|
| 722 |
|
|
we_r <= we_r;
|
| 723 |
|
|
end if;
|
| 724 |
|
|
end if;
|
| 725 |
|
|
end if;
|
| 726 |
|
|
end process;
|
| 727 |
|
|
|
| 728 |
|
|
rw <= we and we_r;
|
| 729 |
|
|
|
| 730 |
|
|
-- data bus tristate (buffer ring gated) control logic
|
| 731 |
|
|
--process(clk0,we,we_r,alu_bus)
|
| 732 |
|
|
--begin
|
| 733 |
|
|
-- if clock = '0' and (we = '0' or we_r = '0') then
|
| 734 |
|
|
-- data <= alu_bus;
|
| 735 |
|
|
-- else
|
| 736 |
|
|
-- data <= "ZZZZZZZZ";
|
| 737 |
|
|
-- end if;
|
| 738 |
|
|
--end process;
|
| 739 |
|
|
data_out <= alu_bus;
|
| 740 |
|
|
dbin <= data_in or "00000000";
|
| 741 |
|
|
|
| 742 |
|
|
end struct;
|
| 743 |
|
|
|
| 744 |
|
|
|
| 745 |
|
|
|
