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`timescale 1ns / 1ps
//////////////////////////////////////////////////////////////////////////////////
// Company:   BMSTU
// Engineer:  Oleg Odintsov
// 
// Create Date:    10:50:36 02/15/2012 
// Design Name: 
// Module Name:    ag_6502 
// Project Name:    Agat Hardware Project
// Target Devices: 
// Tool versions: 
// Description: 
//
// Dependencies: 
//
// Revision: 
// Revision 0.01 - File Created
// Additional Comments: 
//
//////////////////////////////////////////////////////////////////////////////////
 
 
// Specify following define to allow external 
//              clocking for phi1 and phi2
//      In such case you may use ag6502_ext_clock module
//              with baseclk frequency ~ 10 x phi_0
`define AG6502_EXTERNAL_CLOCK
 
 
`ifndef AG6502_EXTERNAL_CLOCK
module ag6502_clock(input phi_0, output phi_1, output phi_2);
        wire phi_01;
        not#3(phi_1,phi_0);
        or(phi_01,~phi_0, phi_1);
        not#1(phi_2, phi_01);
endmodule
 
 
`else
 
module ag6502_phase_shift(input baseclk, input phi_0, output reg phi_1);
        parameter DELAY = 1; // delay in semi-waves of baseclk
        initial phi_1 = 0;
        integer cnt = 0;
 
        always @(posedge baseclk) begin
                if (phi_0 != phi_1) begin
                        if (!cnt) begin phi_1 <= ~phi_1; cnt <= DELAY; end
                        else cnt <= cnt - 1;
                end
        end
endmodule
 
// baseclk is used to simulate delays on a real hardware
module ag6502_ext_clock(input baseclk, input phi_0, output phi_1, output phi_2);
        parameter DELAY1 = 3, DELAY2 = 1; // delays in semi-waves of baseclk
 
        wire phi_1_neg, phi_01;
 
        ag6502_phase_shift#DELAY1 d1(baseclk, phi_0, phi_1_neg);
        assign phi_1 = ~phi_1_neg;
 
        and(phi_01, phi_0, phi_1_neg);
        ag6502_phase_shift#DELAY2 d2(baseclk, phi_01, phi_2);
endmodule
 
`endif
 
 
`define ALU_ORA 3'd0
`define ALU_AND 3'd1
`define ALU_EOR 3'd2
`define ALU_ADC 3'd3
`define ALU_ASL 3'd4
`define ALU_LSR 3'd5
`define ALU_ROL 3'd6
`define ALU_ROR 3'd7
 
 
module ag6502_decimal(ADD, D_IN, NEG, CORR);
        input wire[4:0] ADD;
        input wire D_IN, NEG;
        output wire[4:0] CORR;
        wire C9 = {ADD[4]^NEG, ADD[3:0]} > 5'd9;
 
        assign CORR = D_IN?{C9^NEG, C9?ADD[3:0] + (NEG?4'd10:4'd6): ADD[3:0]}: ADD;
endmodule
 
 
module ag6502_alu(A, B, OP, NEG, C_IN, D_IN, R, C_OUT, V_OUT);
        input wire[7:0] A, B;
        input wire[2:0] OP;
        input wire C_IN, D_IN, NEG;
        output wire[7:0] R;
        output wire C_OUT, V_OUT;
 
        wire[4:0] ADD_L;
        ag6502_decimal DL({1'b0, A[3:0]} + {1'b0, B[3:0]} + C_IN, D_IN, NEG, ADD_L);
        wire CF_H = ADD_L[4];
 
        wire[4:0] ADD_H;
        ag6502_decimal DH({1'b0, A[7:4]} + {1'b0, B[7:4]} + CF_H, D_IN, NEG, ADD_H);
 
        assign
                {C_OUT,R} = (OP==`ALU_ORA)? A | B:
                                (OP==`ALU_AND)? A & B:
                                (OP==`ALU_EOR)? A ^ B:
                                (OP==`ALU_ADC)? {ADD_H, ADD_L[3:0]}:
                                (OP==`ALU_ASL)? {A[7], A[6:0], 1'b0}:
                                (OP==`ALU_LSR)? {A[0], 1'b0, A[7:1]}:
                                (OP==`ALU_ROL)? {A[7], A[6:0], C_IN}:
                                (OP==`ALU_ROR)? {A[0], C_IN, A[7:1]}:
                                8'bX;
        assign V_OUT = (A[7] == B[7]) && (A[7] != R[7]);
endmodule
 
/*
        System AB/DB discipline:
        1. For CPU
                Phi1 up => CPU set ab/db_out buses
                Phi2 down => CPU reads data from db_in
        2. For Memory / other devices
                Phi2 up => perform read/write operation
*/
 
 
module ag6502(input phi_0,
`ifdef AG6502_EXTERNAL_CLOCK
                input phi_1, input phi_2,
`else
                output phi_1, output phi_2,
`endif
                output reg[15:0] ab,
                output wire read,
                input[7:0] db_in, output reg[7:0] db_out,
                input rdy,
                input rst, input irq, input nmi,
                input so,
                output sync);
 
`ifndef AG6502_EXTERNAL_CLOCK
        ag6502_clock cgen(phi_0, phi_1, phi_2);
`endif
 
        reg rdyg = 1;
 
        reg[2:0] T = 7;
        reg[7:0] IR ='h18;
 
        reg[15:0] PC = 0;
        wire[7:0] PCH = PC[15:8], PCL = PC[7:0];
        reg[7:0] EAL, EAH;
        wire[15:0] EA = {EAH, EAL};
 
        reg FLAG_C, FLAG_Z, FLAG_I, FLAG_D, FLAG_B, FLAG_V, FLAG_N;
 
        reg[7:0] AC, X, Y, S = 0;
        wire[7:0] P = {FLAG_N, FLAG_V, 1'b1, FLAG_B, FLAG_D, FLAG_I, FLAG_Z, FLAG_C};
        wire[7:0] SB;
 
 
        wire[7:0] ALU_A, ALU_B;
        wire[7:0] RES;
        wire[2:0] ALU_OP;
        reg[8:0] eALU; // with carry
        wire[7:0] ALU = eALU;
        wire ALU_CF = eALU[8];
 
        wire CF_IN, DF_IN;
        wire CF_OUT, VF_OUT;
 
        reg so_prev = 0;
        reg nmi_prev = 0;
        wire irq_active = ~irq & ~FLAG_I;
        wire nmi_active = ~nmi & nmi_prev;
        wire int_active = irq_active | nmi_active;
        wire rst_active = ~rst;
        wire so_active = so & ~so_prev;
 
        wire[1:0] vec_bits=
                        nmi_active?2'b01:
                        rst_active?2'b10:
                        2'b11;
 
        wire[15:0] vec_addr = {{13{1'b1}}, vec_bits, 1'b0};
 
        wire[7:0] IR_eff = int_active?8'b0:IR;
 
        wire[10:0] L = {T, IR_eff};
 
        `include "states.v"
 
        assign read = ~A_RW_W;
        assign sync = !T;
 
        assign SB = A_SB_DB? db_in:
                                        A_SB_AC? AC:
                                        A_SB_X? X:
                                        A_SB_Y? Y:
                                        A_SB_S? S:
                                        A_SB_P? P:
                                        A_SB_ALU? ALU:
                                        A_SB_0? 8'b0:
                                        A_SB_PCH? PCH:
                                        A_SB_PCL? PCL:
                                        8'bX;
 
        assign CF_IN = A_ALU_CF_0? 1'b0:
                                        A_ALU_CF_1? 1'b1:
                                        A_ALU_CF_ALUC? ALU_CF:
                                        FLAG_C;
 
        assign DF_IN = A_ALU_DF_D? FLAG_D: 1'b0;
 
        assign ALU_A =
                                        A_ALU_A_AC? AC:
                                        A_ALU_A_X? X:
                                        A_ALU_A_Y? Y:
                                        A_ALU_A_DB? db_in:
                                        A_ALU_A_EAL? EAL:
                                        A_ALU_A_ALU? ALU:
                                        A_ALU_A_S? S:
                                        A_ALU_A_SIGN? (EAL[7]?8'b11111111:8'b00000001):
                                        8'bX;
 
        assign ALU_B = A_ALU_B_SB? SB:
                                        A_ALU_B_NOTSB? ~SB:
                                        8'bX;
 
        assign ALU_OP = A_ALU_OP_ADC? `ALU_ADC:
                                        A_ALU_OP_ORA? `ALU_ORA:
                                        A_ALU_OP_EOR? `ALU_EOR:
                                        A_ALU_OP_AND? `ALU_AND:
                                        A_ALU_OP_ASL? `ALU_ASL:
                                        A_ALU_OP_LSR? `ALU_LSR:
                                        A_ALU_OP_ROL? `ALU_ROL:
                                        A_ALU_OP_ROR? `ALU_ROR:
                                        8'bX;
 
        ag6502_alu alu(ALU_A, ALU_B, ALU_OP, A_ALU_B_NOTSB, CF_IN, DF_IN, RES, CF_OUT, VF_OUT);
 
        always @(posedge phi_1) begin
                if (E_AB__PC) ab <= PC;
                else if (E_AB__EA) ab <= EA;
                else if (E_AB__S) ab <= {8'b1, S};
 
                if (E_DB__SB) db_out <= SB;
                else if (E_DB__PCH) db_out <= PCH;
                else if (E_DB__PCL) db_out <= PCL;
                else if (E_DB__P) db_out <= P;
                else if (E_DB__ALU) db_out <= ALU;
 
                if (read) rdyg <= rdy;
        end
 
 
        wire cond;
 
        assign cond =
                        E_T__0IFNF__IR_5_?(FLAG_N != IR[5]):
                        E_T__0IFVF__IR_5_?(FLAG_V != IR[5]):
                        E_T__0IFCF__IR_5_?(FLAG_C != IR[5]):
                        E_T__0IFZF__IR_5_?(FLAG_Z != IR[5]):
                        E_T__0IFZF__IR_5_?(FLAG_Z != IR[5]):
                        E_T__0IF_C7F? CF_OUT == EAL[7]:
                        E_T__0;
 
        always @(negedge phi_2) if (rdyg) begin
                if (E_PC__PC_1) PC <= PC + 1;
                else if (E_PC__EA) PC <= EA;
                else begin
                        if (E_PCH__RES) PC[15:8] <= RES;
                        if (E_PCL__ALU) PC[7:0] <= ALU;
                        else if (E_PCL__RES) PC[7:0] <= RES;
                        else if (E_PCL__EAL) PC[7:0] <= EAL;
                        else if (E_PCL__DB) PC[7:0] <= db_in;
                end
 
                if (!T) begin
                        IR <= db_in;
                        if (!db_in) begin // BRK instruction
                                {EAH, EAL} <= vec_addr;
                        end
                        nmi_prev <= nmi;
                end
 
                if (E_N_Z__SB) begin FLAG_Z <= !SB; FLAG_N <= SB[7]; end
                else if (E_N_Z__RES) begin FLAG_Z <= !RES; FLAG_N <= RES[7]; end
                else if (E_N_Z__SB_RES) begin FLAG_Z <= !RES; FLAG_N <= SB[7]; end
 
                if (E_C__RES) FLAG_C <= CF_OUT;
                if (E_V__RES) FLAG_V <= VF_OUT;
                else if (E_V__SB_6_) FLAG_V <= SB[6];
 
                if (E_EAL__DB) EAL <= db_in;
                else if (E_EAL__ALU) EAL <= ALU;
 
 
                if (E_EA__DB) {EAH, EAL} <= { 8'b0, db_in };
                else if (E_EAH__DB) EAH <= db_in;
                else if (E_EAH__ALU) EAH <= ALU;
 
                if (E_AC__SB) AC <= SB;
                else if (E_AC__RES) AC <= RES;
 
                if (E_S__ALU) S <= ALU;
 
                if (E_X__SB) X <= SB;
                else if (E_X__RES) X <= RES;
 
                if (E_Y__SB) Y <= SB;
                else if (E_Y__RES) Y <= RES;
 
                if (E_S__SB) S <= SB;
                if (E_P__SB) {FLAG_N, FLAG_V, FLAG_B, FLAG_D, FLAG_I, FLAG_Z, FLAG_C} <= {SB[7], SB[6], SB[4], SB[3], SB[2], SB[1], SB[0]};
                else if (E_P__DB) {FLAG_N, FLAG_V, FLAG_B, FLAG_D, FLAG_I, FLAG_Z, FLAG_C} <= {db_in[7], db_in[6], db_in[4], db_in[3], db_in[2], db_in[1], db_in[0]};
 
                if (E_CF__IR_5_) FLAG_C <= IR[5];
                if (E_IF__IR_5_) FLAG_I <= IR[5];
                if (E_DF__IR_5_) FLAG_D <= IR[5];
                if (E_VF__0) FLAG_V <= 0;
                else if (so_active) FLAG_V <= 1;
                so_prev <= so;
 
                eALU <= {CF_OUT, RES};
 
                if (cond) begin
                        T <= 0;
                        if (!IR_eff) begin
                                FLAG_B <= !IR;
                                FLAG_I <= 1;
                        end
                end else T <= T + ((E_T__T_1IF_ALUCZ && !ALU_CF)?2: 1);
 
                if (rst_active) begin
                        T <= 1;
                        IR <= 0;
                        {EAH, EAL} <= vec_addr;
                end
        end
 
 
endmodule
 

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Subversion Repositories ag_6502

[/] [ag_6502/] [trunk/] [agat7/] [ag_6502.v] - Blame information for rev 2

Line No.	Rev	Author	Line
1	2	olegodints	`timescale 1ns / 1ps
2			`//////////////////////////////////////////////////////////////////////////////////`
3			`// Company: BMSTU`
4			`// Engineer: Oleg Odintsov`
5			`//`
6			`// Create Date: 10:50:36 02/15/2012`
7			`// Design Name:`
8			`// Module Name: ag_6502`
9			`// Project Name: Agat Hardware Project`
10			`// Target Devices:`
11			`// Tool versions:`
12			`// Description:`
13			`//`
14			`// Dependencies:`
15			`//`
16			`// Revision:`
17			`// Revision 0.01 - File Created`
18			`// Additional Comments:`
19			`//`
20			`//////////////////////////////////////////////////////////////////////////////////`
21
22
23			`// Specify following define to allow external`
24			`// clocking for phi1 and phi2`
25			`// In such case you may use ag6502_ext_clock module`
26			`// with baseclk frequency ~ 10 x phi_0`
27			`define AG6502_EXTERNAL_CLOCK
28
29
30			`ifndef AG6502_EXTERNAL_CLOCK
31			`module ag6502_clock(input phi_0, output phi_1, output phi_2);`
32			`wire phi_01;`
33			`not#3(phi_1,phi_0);`
34			`or(phi_01,~phi_0, phi_1);`
35			`not#1(phi_2, phi_01);`
36			`endmodule`
37
38
39			`else
40
41			`module ag6502_phase_shift(input baseclk, input phi_0, output reg phi_1);`
42			`parameter DELAY = 1; // delay in semi-waves of baseclk`
43			`initial phi_1 = 0;`
44			`integer cnt = 0;`
45
46			`always @(posedge baseclk) begin`
47			`if (phi_0 != phi_1) begin`
48			`if (!cnt) begin phi_1 <= ~phi_1; cnt <= DELAY; end`
49			`else cnt <= cnt - 1;`
50			`end`
51			`end`
52			`endmodule`
53
54			`// baseclk is used to simulate delays on a real hardware`
55			`module ag6502_ext_clock(input baseclk, input phi_0, output phi_1, output phi_2);`
56			`parameter DELAY1 = 3, DELAY2 = 1; // delays in semi-waves of baseclk`
57
58			`wire phi_1_neg, phi_01;`
59
60			`ag6502_phase_shift#DELAY1 d1(baseclk, phi_0, phi_1_neg);`
61			`assign phi_1 = ~phi_1_neg;`
62
63			`and(phi_01, phi_0, phi_1_neg);`
64			`ag6502_phase_shift#DELAY2 d2(baseclk, phi_01, phi_2);`
65			`endmodule`
66
67			`endif
68
69
70			`define ALU_ORA 3'd0
71			`define ALU_AND 3'd1
72			`define ALU_EOR 3'd2
73			`define ALU_ADC 3'd3
74			`define ALU_ASL 3'd4
75			`define ALU_LSR 3'd5
76			`define ALU_ROL 3'd6
77			`define ALU_ROR 3'd7
78
79
80			`module ag6502_decimal(ADD, D_IN, NEG, CORR);`
81			`input wire[4:0] ADD;`
82			`input wire D_IN, NEG;`
83			`output wire[4:0] CORR;`
84			`wire C9 = {ADD[4]^NEG, ADD[3:0]} > 5'd9;`
85
86			`assign CORR = D_IN?{C9^NEG, C9?ADD[3:0] + (NEG?4'd10:4'd6): ADD[3:0]}: ADD;`
87			`endmodule`
88
89
90			`module ag6502_alu(A, B, OP, NEG, C_IN, D_IN, R, C_OUT, V_OUT);`
91			`input wire[7:0] A, B;`
92			`input wire[2:0] OP;`
93			`input wire C_IN, D_IN, NEG;`
94			`output wire[7:0] R;`
95			`output wire C_OUT, V_OUT;`
96
97			`wire[4:0] ADD_L;`
98			`ag6502_decimal DL({1'b0, A[3:0]} + {1'b0, B[3:0]} + C_IN, D_IN, NEG, ADD_L);`
99			`wire CF_H = ADD_L[4];`
100
101			`wire[4:0] ADD_H;`
102			`ag6502_decimal DH({1'b0, A[7:4]} + {1'b0, B[7:4]} + CF_H, D_IN, NEG, ADD_H);`
103
104			`assign`
105			{C_OUT,R} = (OP==`ALU_ORA)? A \| B:
106			(OP==`ALU_AND)? A & B:
107			(OP==`ALU_EOR)? A ^ B:
108			(OP==`ALU_ADC)? {ADD_H, ADD_L[3:0]}:
109			(OP==`ALU_ASL)? {A[7], A[6:0], 1'b0}:
110			(OP==`ALU_LSR)? {A[0], 1'b0, A[7:1]}:
111			(OP==`ALU_ROL)? {A[7], A[6:0], C_IN}:
112			(OP==`ALU_ROR)? {A[0], C_IN, A[7:1]}:
113			`8'bX;`
114			`assign V_OUT = (A[7] == B[7]) && (A[7] != R[7]);`
115			`endmodule`
116
117			`/*`
118			`System AB/DB discipline:`
119			`1. For CPU`
120			`Phi1 up => CPU set ab/db_out buses`
121			`Phi2 down => CPU reads data from db_in`
122			`2. For Memory / other devices`
123			`Phi2 up => perform read/write operation`
124			`*/`
125
126
127			`module ag6502(input phi_0,`
128			`ifdef AG6502_EXTERNAL_CLOCK
129			`input phi_1, input phi_2,`
130			`else
131			`output phi_1, output phi_2,`
132			`endif
133			`output reg[15:0] ab,`
134			`output wire read,`
135			`input[7:0] db_in, output reg[7:0] db_out,`
136			`input rdy,`
137			`input rst, input irq, input nmi,`
138			`input so,`
139			`output sync);`
140
141			`ifndef AG6502_EXTERNAL_CLOCK
142			`ag6502_clock cgen(phi_0, phi_1, phi_2);`
143			`endif
144
145			`reg rdyg = 1;`
146
147			`reg[2:0] T = 7;`
148			`reg[7:0] IR ='h18;`
149
150			`reg[15:0] PC = 0;`
151			`wire[7:0] PCH = PC[15:8], PCL = PC[7:0];`
152			`reg[7:0] EAL, EAH;`
153			`wire[15:0] EA = {EAH, EAL};`
154
155			`reg FLAG_C, FLAG_Z, FLAG_I, FLAG_D, FLAG_B, FLAG_V, FLAG_N;`
156
157			`reg[7:0] AC, X, Y, S = 0;`
158			`wire[7:0] P = {FLAG_N, FLAG_V, 1'b1, FLAG_B, FLAG_D, FLAG_I, FLAG_Z, FLAG_C};`
159			`wire[7:0] SB;`
160
161
162			`wire[7:0] ALU_A, ALU_B;`
163			`wire[7:0] RES;`
164			`wire[2:0] ALU_OP;`
165			`reg[8:0] eALU; // with carry`
166			`wire[7:0] ALU = eALU;`
167			`wire ALU_CF = eALU[8];`
168
169			`wire CF_IN, DF_IN;`
170			`wire CF_OUT, VF_OUT;`
171
172			`reg so_prev = 0;`
173			`reg nmi_prev = 0;`
174			`wire irq_active = ~irq & ~FLAG_I;`
175			`wire nmi_active = ~nmi & nmi_prev;`
176			`wire int_active = irq_active \| nmi_active;`
177			`wire rst_active = ~rst;`
178			`wire so_active = so & ~so_prev;`
179
180			`wire[1:0] vec_bits=`
181			`nmi_active?2'b01:`
182			`rst_active?2'b10:`
183			`2'b11;`
184
185			`wire[15:0] vec_addr = {{13{1'b1}}, vec_bits, 1'b0};`
186
187			`wire[7:0] IR_eff = int_active?8'b0:IR;`
188
189			`wire[10:0] L = {T, IR_eff};`
190
191			`include "states.v"
192
193			`assign read = ~A_RW_W;`
194			`assign sync = !T;`
195
196			`assign SB = A_SB_DB? db_in:`
197			`A_SB_AC? AC:`
198			`A_SB_X? X:`
199			`A_SB_Y? Y:`
200			`A_SB_S? S:`
201			`A_SB_P? P:`
202			`A_SB_ALU? ALU:`
203			`A_SB_0? 8'b0:`
204			`A_SB_PCH? PCH:`
205			`A_SB_PCL? PCL:`
206			`8'bX;`
207
208			`assign CF_IN = A_ALU_CF_0? 1'b0:`
209			`A_ALU_CF_1? 1'b1:`
210			`A_ALU_CF_ALUC? ALU_CF:`
211			`FLAG_C;`
212
213			`assign DF_IN = A_ALU_DF_D? FLAG_D: 1'b0;`
214
215			`assign ALU_A =`
216			`A_ALU_A_AC? AC:`
217			`A_ALU_A_X? X:`
218			`A_ALU_A_Y? Y:`
219			`A_ALU_A_DB? db_in:`
220			`A_ALU_A_EAL? EAL:`
221			`A_ALU_A_ALU? ALU:`
222			`A_ALU_A_S? S:`
223			`A_ALU_A_SIGN? (EAL[7]?8'b11111111:8'b00000001):`
224			`8'bX;`
225
226			`assign ALU_B = A_ALU_B_SB? SB:`
227			`A_ALU_B_NOTSB? ~SB:`
228			`8'bX;`
229
230			assign ALU_OP = A_ALU_OP_ADC? `ALU_ADC:
231			A_ALU_OP_ORA? `ALU_ORA:
232			A_ALU_OP_EOR? `ALU_EOR:
233			A_ALU_OP_AND? `ALU_AND:
234			A_ALU_OP_ASL? `ALU_ASL:
235			A_ALU_OP_LSR? `ALU_LSR:
236			A_ALU_OP_ROL? `ALU_ROL:
237			A_ALU_OP_ROR? `ALU_ROR:
238			`8'bX;`
239
240			`ag6502_alu alu(ALU_A, ALU_B, ALU_OP, A_ALU_B_NOTSB, CF_IN, DF_IN, RES, CF_OUT, VF_OUT);`
241
242			`always @(posedge phi_1) begin`
243			`if (E_AB__PC) ab <= PC;`
244			`else if (E_AB__EA) ab <= EA;`
245			`else if (E_AB__S) ab <= {8'b1, S};`
246
247			`if (E_DB__SB) db_out <= SB;`
248			`else if (E_DB__PCH) db_out <= PCH;`
249			`else if (E_DB__PCL) db_out <= PCL;`
250			`else if (E_DB__P) db_out <= P;`
251			`else if (E_DB__ALU) db_out <= ALU;`
252
253			`if (read) rdyg <= rdy;`
254			`end`
255
256
257			`wire cond;`
258
259			`assign cond =`
260			`E_T__0IFNF__IR_5_?(FLAG_N != IR[5]):`
261			`E_T__0IFVF__IR_5_?(FLAG_V != IR[5]):`
262			`E_T__0IFCF__IR_5_?(FLAG_C != IR[5]):`
263			`E_T__0IFZF__IR_5_?(FLAG_Z != IR[5]):`
264			`E_T__0IFZF__IR_5_?(FLAG_Z != IR[5]):`
265			`E_T__0IF_C7F? CF_OUT == EAL[7]:`
266			`E_T__0;`
267
268			`always @(negedge phi_2) if (rdyg) begin`
269			`if (E_PC__PC_1) PC <= PC + 1;`
270			`else if (E_PC__EA) PC <= EA;`
271			`else begin`
272			`if (E_PCH__RES) PC[15:8] <= RES;`
273			`if (E_PCL__ALU) PC[7:0] <= ALU;`
274			`else if (E_PCL__RES) PC[7:0] <= RES;`
275			`else if (E_PCL__EAL) PC[7:0] <= EAL;`
276			`else if (E_PCL__DB) PC[7:0] <= db_in;`
277			`end`
278
279			`if (!T) begin`
280			`IR <= db_in;`
281			`if (!db_in) begin // BRK instruction`
282			`{EAH, EAL} <= vec_addr;`
283			`end`
284			`nmi_prev <= nmi;`
285			`end`
286
287			`if (E_N_Z__SB) begin FLAG_Z <= !SB; FLAG_N <= SB[7]; end`
288			`else if (E_N_Z__RES) begin FLAG_Z <= !RES; FLAG_N <= RES[7]; end`
289			`else if (E_N_Z__SB_RES) begin FLAG_Z <= !RES; FLAG_N <= SB[7]; end`
290
291			`if (E_C__RES) FLAG_C <= CF_OUT;`
292			`if (E_V__RES) FLAG_V <= VF_OUT;`
293			`else if (E_V__SB_6_) FLAG_V <= SB[6];`
294
295			`if (E_EAL__DB) EAL <= db_in;`
296			`else if (E_EAL__ALU) EAL <= ALU;`
297
298
299			`if (E_EA__DB) {EAH, EAL} <= { 8'b0, db_in };`
300			`else if (E_EAH__DB) EAH <= db_in;`
301			`else if (E_EAH__ALU) EAH <= ALU;`
302
303			`if (E_AC__SB) AC <= SB;`
304			`else if (E_AC__RES) AC <= RES;`
305
306			`if (E_S__ALU) S <= ALU;`
307
308			`if (E_X__SB) X <= SB;`
309			`else if (E_X__RES) X <= RES;`
310
311			`if (E_Y__SB) Y <= SB;`
312			`else if (E_Y__RES) Y <= RES;`
313
314			`if (E_S__SB) S <= SB;`
315			`if (E_P__SB) {FLAG_N, FLAG_V, FLAG_B, FLAG_D, FLAG_I, FLAG_Z, FLAG_C} <= {SB[7], SB[6], SB[4], SB[3], SB[2], SB[1], SB[0]};`
316			`else if (E_P__DB) {FLAG_N, FLAG_V, FLAG_B, FLAG_D, FLAG_I, FLAG_Z, FLAG_C} <= {db_in[7], db_in[6], db_in[4], db_in[3], db_in[2], db_in[1], db_in[0]};`
317
318			`if (E_CF__IR_5_) FLAG_C <= IR[5];`
319			`if (E_IF__IR_5_) FLAG_I <= IR[5];`
320			`if (E_DF__IR_5_) FLAG_D <= IR[5];`
321			`if (E_VF__0) FLAG_V <= 0;`
322			`else if (so_active) FLAG_V <= 1;`
323			`so_prev <= so;`
324
325			`eALU <= {CF_OUT, RES};`
326
327			`if (cond) begin`
328			`T <= 0;`
329			`if (!IR_eff) begin`
330			`FLAG_B <= !IR;`
331			`FLAG_I <= 1;`
332			`end`
333			`end else T <= T + ((E_T__T_1IF_ALUCZ && !ALU_CF)?2: 1);`
334
335			`if (rst_active) begin`
336			`T <= 1;`
337			`IR <= 0;`
338			`{EAH, EAL} <= vec_addr;`
339			`end`
340			`end`
341
342
343			`endmodule`
344