fix doc + add 8 regs

README.md

@@ -20,7 +20,7 @@ make
 
 - 8-bit processing unit
 - RISC (reduced instruction set computer)
-- 4 general purpose registers (labeled R0 to R3)
+- 8 general purpose registers (labeled Rx)
 - 1 input port, 1 output port (via getchar and putchar)
 - Turing-completeness: bitwise and arithmetic operations
 
@@ -33,9 +33,11 @@ MOV RX, RY
 ; Put value X in register RX
 PUT RX, X
 
-; Arithmetic addition and substraction stored in RX
+; Arithmetic operations. Result stored in RX
 ADD RX, RY
 SUB RX, RY
+MUL RX, RY
+DIV RX, RY
 
 ; Bitwise operations stored in RX
 OR RX, RY

cpu.c

@@ -196,10 +196,10 @@ void cpu_run()
 void cpu_dump()
 {
 	printf("\n*** CPU state dump ***\nPC: 0x%x\nEqual flag: %d\nHalted: %d\n\n", cpu.pc, cpu.equal_flag, cpu.halted);
-	
-	for (size_t i=0; i<NUM_REGISTERS; i++)
+
+	for (size_t i=1; i<NUM_REGISTERS; i+=2)
 	{
-		printf("R%lu: 0x%x\n", i, cpu.reg[i]);
+		printf("R%lu: 0x%04x  R%lu: 0x%04x\n", i, cpu.reg[i], i+1, cpu.reg[i+1]);
 	}
 	puts("");
 }

cpu.h

@@ -2,7 +2,7 @@
 #define CPU_H
 
 #define MEM_SIZE	256
-#define NUM_REGISTERS	4
+#define NUM_REGISTERS	8
 #define BUF_MAX     256
 
 /*