diff --git a/src/device.c b/src/device.c
new file mode 100644
index 0000000..c6cc2f3
--- /dev/null
+++ b/src/device.c
@@ -0,0 +1,12 @@
+#include "device.h"
+
+Device* createDevice(
+    const char* name,
+    void (*sendToDevice)(uint16_t number),
+    uint16_t (*receiveFromDevice)(),
+    void (*update)()
+) {
+    Device* new = malloc(sizeof(Device));
+    if (!new)
+        return NULL;
+}
\ No newline at end of file
diff --git a/src/device.h b/src/device.h
index 2473ca0..d4c797d 100644
--- a/src/device.h
+++ b/src/device.h
@@ -1,5 +1,18 @@
 #pragma once
+#include <stdint.h>
+#include <stdlib.h>
 
 typedef struct {
+    char name[32];
 
-} Device;
\ No newline at end of file
+    void (*sendToDevice)(uint16_t number);
+    uint16_t (*receiveFromDevice)();
+    void (*update)();
+} Device;
+
+Device* createDevice(
+    const char* name,
+    void (*sendToDevice)(uint16_t number),
+    uint16_t (*receiveFromDevice)(),
+    void (*update)()
+);
\ No newline at end of file
diff --git a/src/instruction.c b/src/instruction.c
index a4f8f2e..08eb147 100644
--- a/src/instruction.c
+++ b/src/instruction.c
@@ -13,7 +13,7 @@ const OperandType INSTRUCTION_OPERAND_TYPES[][3] = {
     {OP_REG, OP_REG,  OP_REG},     // SHF
     {OP_REG, OP_REG,  OP_NONE},   // JMP
     {OP_REG, OP_REG,  OP_NONE},   // JIZ
-    {OP_REG, OP_REG,  OP_NONE},   // CALL
+    {OP_IMM16, OP_NONE,  OP_NONE},// CALL
     {OP_NONE, OP_NONE,  OP_NONE}, // RET
     {OP_REG, OP_REG,  OP_IMM4},   // PORT
     {OP_NONE, OP_NONE,  OP_NONE}  // HLT
diff --git a/src/instruction.h b/src/instruction.h
index 4bffb60..d026009 100644
--- a/src/instruction.h
+++ b/src/instruction.h
@@ -11,7 +11,7 @@ typedef enum : uint8_t {
     INST_XOR, INST_SHF, INST_JMP, INST_JIZ, INST_CALL, INST_RET,   INST_PORT, INST_HLT
 } InstructionOpcode;
 
-typedef enum {
+typedef enum : uint8_t {
     // General purpose registers
     REG_A, REG_B, REG_C,
 
diff --git a/src/main.c b/src/main.c
index e458cbb..f24ee11 100644
--- a/src/main.c
+++ b/src/main.c
@@ -10,16 +10,7 @@ int main() {
     }
 
     RomFile* romFile = readProgramFromFile("../test.bin");
-
-    /*Instruction program[] = {
-        {INST_MVI, {REG_A, 0, 0}, 5, true},
-        {INST_MVI, {REG_B, 0, 0}, 3, true},
-        {INST_ADD, {REG_A, REG_B, 0}, 0, false},
-        {INST_HLT, {}, 0, false}
-    };*/
-    printf("%d\n", romFile->header.numInstructions);
     memoryLoadProgram(emu->mem, romFile->instructions, romFile->header.numInstructions);
-    
 
     //startEmulator(emu);
     freeEmulator(emu);
diff --git a/tests/add.asm b/tests/add.asm
index 843c9bd..c0ee31a 100644
--- a/tests/add.asm
+++ b/tests/add.asm
@@ -2,4 +2,4 @@ mvi a 2
 mvi b 2
 
 add a b
-hlt
+hlt
\ No newline at end of file
diff --git a/tests/port.asm b/tests/port.asm
new file mode 100644
index 0000000..0abf7f1
--- /dev/null
+++ b/tests/port.asm
@@ -0,0 +1,3 @@
+mvi a 1
+port a 123 out
+hlt
\ No newline at end of file