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Z80: Daves's fixes to T80 for ICE-Z80 

Change-Id: Id1530b7c3f433ff2ff2b6f7966e3c93657058761
This commit is contained in:
David Banks 2021-06-30 13:18:15 +01:00
parent 670328574b
commit e65951cfbb
3 changed files with 129 additions and 73 deletions
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4
src/T80/T80.vhd
View File

@ -117,6 +117,7 @@ entity T80 is
MC : out std_logic_vector(2 downto 0);
TS : out std_logic_vector(2 downto 0);
IntCycle_n : out std_logic;
NMICycle_n : out std_logic;
IntE : out std_logic;
Stop : out std_logic;
R800_mode : in std_logic := '0';
@ -682,7 +683,7 @@ begin
F(Flag_N) <= DI_Reg(7);
F(Flag_C) <= ioq(8);
F(Flag_H) <= ioq(8);
ioq := (ioq and x"7") xor ('0'&BusA);
ioq := (ioq and ('0'&x"07")) xor ('0'&BusA);
F(Flag_P) <= not (ioq(0) xor ioq(1) xor ioq(2) xor ioq(3) xor ioq(4) xor ioq(5) xor ioq(6) xor ioq(7));
end if;
@ -1193,6 +1194,7 @@ begin
HALT_n <= not Halt_FF;
BUSAK_n <= not (BusAck and RESET_n);
IntCycle_n <= not IntCycle;
NMICycle_n <= not NMICycle;
IntE <= IntE_FF1;
IORQ <= IORQ_i;
Stop <= I_DJNZ;

1
src/T80/T80_Pack.vhd
View File

@ -103,6 +103,7 @@ package T80_Pack is
MC : out std_logic_vector(2 downto 0);
TS : out std_logic_vector(2 downto 0);
IntCycle_n : out std_logic;
NMICycle_n : out std_logic;
IntE : out std_logic;
Stop : out std_logic;
R800_mode : in std_logic := '0';

197
src/T80/T80a.vhd
View File

@ -85,8 +85,17 @@ entity T80a is
IOWait : integer := 1 -- 0 => Single I/O cycle, 1 => Std I/O cycle
);
port(
-- DMB
TS : out std_logic_vector(2 downto 0);
Regs : out std_logic_vector(255 downto 0);
PdcData : out std_logic_vector(7 downto 0);
CEN : in std_logic;
Din : in std_logic_vector(7 downto 0);
Dout : out std_logic_vector(7 downto 0);
Den : out std_logic;
-- Original Signals
RESET_n : in std_logic;
R800_mode : in std_logic;
R800_mode : in std_logic := '0';
CLK_n : in std_logic;
WAIT_n : in std_logic;
INT_n : in std_logic;
@ -100,16 +109,16 @@ entity T80a is
RFSH_n : out std_logic;
HALT_n : out std_logic;
BUSAK_n : out std_logic;
A : out std_logic_vector(15 downto 0);
D : inout std_logic_vector(7 downto 0)
A : out std_logic_vector(15 downto 0)
-- D : inout std_logic_vector(7 downto 0)
);
end T80a;
architecture rtl of T80a is
signal CEN : std_logic;
signal Reset_s : std_logic;
signal IntCycle_n : std_logic;
signal NMICycle_n : std_logic;
signal IORQ : std_logic;
signal NoRead : std_logic;
signal Write : std_logic;
@ -136,11 +145,10 @@ architecture rtl of T80a is
signal Wait_s : std_logic;
signal MCycle : std_logic_vector(2 downto 0);
signal TState : std_logic_vector(2 downto 0);
signal HALT_n_int : std_logic;
begin
CEN <= '1';
BUSAK_n <= BUSAK_n_i; -- 30/10/19 Charlie Ingley - IORQ/RD/WR changes
MREQ_rw <= MREQ and (Req_Inhibit or MReq_Inhibit); -- added MREQ timing control
MREQ_n_i <= not MREQ_rw; -- changed MREQ generation
@ -148,21 +156,34 @@ begin
IORQ_n_i <= not ((IORQ_int and not IORQ_int_inhibit(2)) or IORQ_rw); -- changed IORQ generation
RD_n_i <= not (RD and (MREQ_rw or IORQ_rw)); -- changed RD/IORQ generation
WR_n_i <= not (Write and ((WR_t2 and MREQ_rw) or IORQ_rw)); -- added WR/IORQ timing control
HALT_n <= HALT_n_int;
MREQ_n <= MREQ_n_i when BUSAK_n_i = '1' else 'Z';
IORQ_n <= IORQ_n_i when BUSAK_n_i = '1' else 'Z';
RD_n <= RD_n_i when BUSAK_n_i = '1' else 'Z';
WR_n <= WR_n_i when BUSAK_n_i = '1' else 'Z';
RFSH_n <= RFSH_n_i when BUSAK_n_i = '1' else 'Z';
A <= A_i when BUSAK_n_i = '1' else (others => 'Z');
D <= DO when Write = '1' and BUSAK_n_i = '1' else (others => 'Z');
--Remove tristate as in ICE-Z80 this is implmeneted in Z80CpuMon
--MREQ_n <= MREQ_n_i when BUSAK_n_i = '1' else 'Z';
--IORQ_n <= IORQ_n_i when BUSAK_n_i = '1' else 'Z';
--RD_n <= RD_n_i when BUSAK_n_i = '1' else 'Z';
--WR_n <= WR_n_i when BUSAK_n_i = '1' else 'Z';
--RFSH_n <= RFSH_n_i when BUSAK_n_i = '1' else 'Z';
--A <= A_i when BUSAK_n_i = '1' else (others => 'Z');
--D <= DO when Write = '1' and BUSAK_n_i = '1' else (others => 'Z');
MREQ_n <= MREQ_n_i;
IORQ_n <= IORQ_n_i;
RD_n <= RD_n_i;
WR_n <= WR_n_i;
RFSH_n <= RFSH_n_i;
A <= A_i;
Dout <= DO;
Den <= Write and BUSAK_n_i;
process (RESET_n, CLK_n)
begin
if RESET_n = '0' then
Reset_s <= '0';
elsif CLK_n'event and CLK_n = '1' then
Reset_s <= '1';
if CEN = '1' then
Reset_s <= '1';
end if;
end if;
end process;
@ -178,7 +199,7 @@ begin
NoRead => NoRead,
Write => Write,
RFSH_n => RFSH_n_i,
HALT_n => HALT_n,
HALT_n => HALT_n_int,
WAIT_n => Wait_s,
INT_n => INT_n,
NMI_n => NMI_n,
@ -187,19 +208,29 @@ begin
BUSAK_n => BUSAK_n_i,
CLK_n => CLK_n,
A => A_i,
DInst => D,
DInst => Din,
DI => DI_Reg,
DO => DO,
MC => MCycle,
TS => TState,
IntCycle_n => IntCycle_n);
IntCycle_n => IntCycle_n,
-- DMB
NMICycle_n => NMICycle_n,
REG => Regs(211 downto 0),
DIRSet => '0',
DIR => (others => '0')
);
Regs(255 downto 212) <= (others => '0');
process (CLK_n)
begin
if CLK_n'event and CLK_n = '0' then
Wait_s <= WAIT_n;
if TState = "011" and BUSAK_n_i = '1' then
DI_Reg <= to_x01(D);
if CEN = '1' then
Wait_s <= WAIT_n;
if TState = "011" and BUSAK_n_i = '1' then
DI_Reg <= to_x01(Din);
end if;
end if;
end if;
end process;
@ -210,13 +241,15 @@ begin
if Reset_s = '0' then
WR_t2 <= '0';
elsif CLK_n'event and CLK_n = '0' then
if MCycle /= "001" then
if TState = "010" then -- WR starts on falling edge of T2 for MREQ
WR_t2 <= Write;
if CEN = '1' then
if MCycle /= "001" then
if TState = "010" then -- WR starts on falling edge of T2 for MREQ
WR_t2 <= Write;
end if;
end if;
if TState = "011" then -- end WR
WR_t2 <= '0';
end if;
end if;
if TState = "011" then -- end WR
WR_t2 <= '0';
end if;
end if;
end process;
@ -227,10 +260,12 @@ begin
if Reset_s = '0' then
Req_Inhibit <= '1'; -- Charlie Ingley 30/10/19 - changed Req_Inhibit polarity
elsif CLK_n'event and CLK_n = '1' then
if MCycle = "001" and TState = "010" and WAIT_n = '1' then -- by Fabio Belavenuto - fix behavior of Wait_n
Req_Inhibit <= '0';
else
Req_Inhibit <= '1';
if CEN = '1' then
if MCycle = "001" and TState = "010" and WAIT_n = '1' then -- by Fabio Belavenuto - fix behavior of Wait_n
Req_Inhibit <= '0';
else
Req_Inhibit <= '1';
end if;
end if;
end if;
end process;
@ -241,10 +276,12 @@ begin
if Reset_s = '0' then
MReq_Inhibit <= '1'; -- Charlie Ingley 30/10/19 - changed Req_Inhibit polarity
elsif CLK_n'event and CLK_n = '0' then
if MCycle = "001" and TState = "010" and WAIT_n = '1' then -- by Fabio Belavenuto - fix behavior of Wait_n
MReq_Inhibit <= '0';
else
MReq_Inhibit <= '1';
if CEN = '1' then
if MCycle = "001" and TState = "010" and WAIT_n = '1' then -- by Fabio Belavenuto - fix behavior of Wait_n
MReq_Inhibit <= '0';
else
MReq_Inhibit <= '1';
end if;
end if;
end if;
end process;
@ -256,26 +293,28 @@ begin
RD <= '0';
MREQ <= '0';
elsif CLK_n'event and CLK_n = '0' then
if MCycle = "001" then
if TState = "001" then
RD <= IntCycle_n;
MREQ <= IntCycle_n;
end if;
if TState = "011" then
RD <= '0';
MREQ <= '1';
end if;
if TState = "100" then
MREQ <= '0';
end if;
else
if TState = "001" and NoRead = '0' then
RD <= not Write;
MREQ <= not IORQ;
end if;
if TState = "011" then
RD <= '0';
MREQ <= '0';
if CEN = '1' then
if MCycle = "001" then
if TState = "001" then
RD <= IntCycle_n;
MREQ <= IntCycle_n;
end if;
if TState = "011" then
RD <= '0';
MREQ <= '1';
end if;
if TState = "100" then
MREQ <= '0';
end if;
else
if TState = "001" and NoRead = '0' then
RD <= not Write;
MREQ <= not IORQ;
end if;
if TState = "011" then
RD <= '0';
MREQ <= '0';
end if;
end if;
end if;
end if;
@ -287,12 +326,14 @@ begin
if Reset_s = '0' then
IORQ_int <= '0';
elsif CLK_n'event and CLK_n = '1' then
if MCycle = "001" then
if TState = "001" then
IORQ_int <= not IntCycle_n;
end if;
if TState = "010" then
IORQ_int <= '0';
if CEN = '1' then
if MCycle = "001" then
if TState = "001" then
IORQ_int <= not IntCycle_n;
end if;
if TState = "010" then
IORQ_int <= '0';
end if;
end if;
end if;
end if;
@ -303,12 +344,14 @@ begin
if Reset_s = '0' then
IORQ_int_inhibit <= "111";
elsif CLK_n'event and CLK_n = '0' then
if IntCycle_n = '0' then
if MCycle = "001" then
IORQ_int_inhibit <= IORQ_int_inhibit(1 downto 0) & '0';
end if;
if MCycle = "010" then
IORQ_int_inhibit <= "111";
if CEN = '1' then
if IntCycle_n = '0' then
if MCycle = "001" then
IORQ_int_inhibit <= IORQ_int_inhibit(1 downto 0) & '0';
end if;
if MCycle = "010" then
IORQ_int_inhibit <= "111";
end if;
end if;
end if;
end if;
@ -320,11 +363,13 @@ begin
if Reset_s = '0' then
IORQ_t1 <= '1';
elsif CLK_n'event and CLK_n = '0' then
if TState = "001" then
IORQ_t1 <= not IntCycle_n;
end if;
if TState = "011" then
IORQ_t1 <= '1';
if CEN = '1' then
if TState = "001" then
IORQ_t1 <= not IntCycle_n;
end if;
if TState = "011" then
IORQ_t1 <= '1';
end if;
end if;
end if;
end process;
@ -335,8 +380,16 @@ begin
if RESET_n = '0' then
IORQ_t2 <= '1';
elsif CLK_n'event and CLK_n = '1' then
IORQ_t2 <= IORQ_t1;
if CEN = '1' then
IORQ_t2 <= IORQ_t1;
end if;
end if;
end process;
-- DMB
TS <= TState;
PdcData <= (not HALT_n_int) & (not NMICycle_n) & (not IntCycle_n) & "00000";
end;