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+# Fyntv Architecture Definition
+ARCH Fyntv
+  NAME Fyntv
+  VERSION 0.0.0.1
+  DATE June 2026
+  STATUS Draft
+END
+
+# =============================================================================
+# Instruction Formats
+# =============================================================================
+
+FORMAT R
+  WIDTH 32
+  FIELD opcode  6:0
+  FIELD rd      11:7
+  FIELD funct3  14:12
+  FIELD rs1     19:15
+  FIELD rs2     24:20
+  FIELD funct7  31:25
+END
+
+FORMAT I
+  WIDTH 32
+  FIELD opcode  6:0
+  FIELD rd      11:7
+  FIELD funct3  14:12
+  FIELD rs1     19:15
+  FIELD imm     31:20
+END
+
+FORMAT S
+  WIDTH 32
+  FIELD opcode  6:0
+  FIELD imm_lo  11:7
+  FIELD funct3  14:12
+  FIELD rs1     19:15
+  FIELD rs2     24:20
+  FIELD imm_hi  31:25
+END
+
+FORMAT B
+  WIDTH 32
+  FIELD opcode  6:0
+  FIELD imm_4_1 11:7
+  FIELD funct3  14:12
+  FIELD rs1     19:15
+  FIELD rs2     24:20
+  FIELD imm_10_5 30:25
+  FIELD imm_12  31:31
+END
+
+FORMAT U
+  WIDTH 32
+  FIELD opcode  6:0
+  FIELD rd      11:7
+  FIELD imm     31:12
+END
+
+FORMAT J
+  WIDTH 32
+  FIELD opcode  6:0
+  FIELD rd      11:7
+  FIELD imm_19_12 19:12
+  FIELD imm_11  20:20
+  FIELD imm_10_1 30:21
+  FIELD imm_20  31:31
+END